- Email: [email protected]
Does Caregiver Burden Mediate the Effects of Behavioral Disturbances on Nursing Home Admission?
REGULAR RESEARCH ARTICLES
Does Caregiver Burden Mediate the Effects of Behavioral Disturbances on Nursing Home Admission? Joseph E. Gaugler, Ph.D., Melanie M. Wall, Ph.D., Robert L. Kane, M.D., Jeremiah S. Menk, M.S., Khaled Sarsour, Ph.D., Joseph A. Johnston, M.D., Kory Schuh, Ph.D., Robert Newcomer, Ph.D.
Objectives: The primary objective of this study was to determine whether caregiving burden mediated the relationship between specific behavior disturbances and time to nursing home admission (NHA) for persons with dementia (i.e., Alzheimer disease or a related disorder). Design: The study used secondary longitudinal data from the Medicare Alzheimer’s Disease Demonstration, a Medicare-covered home care benefit and case management program for family caregivers of persons with dementia. Primary caregivers of persons with dementia were assessed via in-person and telephone interviews every 6 months over a 3-year period. Setting: Dementia caregivers were recruited from eight catchment areas throughout the United States. Participants: The baseline sample included 5,831 dementia caregivers. Just more than 40% (43.9%; N = 2,556) of persons with dementia permanently entered a nursing home during the 3-year study period. Measurements: Individual behavior problems were measured with the Memory and Behavior Problem Checklist. Caregiving burden was assessed with a short version of the Zarit Burden Inventory. Key covariates, including sociodemographic background, functional status, and service utilization, were also considered. Results: Event history analyses revealed that time-varying measures of caregiver burden fully mediated the relationship between four behavioral disturbances (episodes of combativeness, property destruction, repetitive questions, and reliving the past) and NHA. Conclusions: The findings highlight the multifaceted, complex pathway to NHA for persons with dementia and their family caregivers. The results emphasize the need for comprehensive treatment approaches that incorporate the burden of caregivers and the behavioral/psychiatric symptoms of persons with dementia simultaneously. (Am J Geriatr Psychiatry 2011; 19:497–506)
Received April 5, 2010; revised October 12, 2010; accepted October 15, 2010. From the School of Nursing, Center on Aging (JEG), University of Minnesota, Minneapolis; Department of Biostatistics, Mailman School of Public Health (MMW), Columbia University, New York, NY; Division of Biostatistics (JSM) and Division of Health Policy and Management (RLK), School of Public Health, University of Minnesota, Minneapolis; Epidemiology and Health Services Research, Global Health Outcomes, Eli Lilly and Company, Indianapolis, IN (K. Sarsour, JAJ, K. Schuh); and Department of Social and Behavioral Science, University of California–San Francisco (RN). Send correspondence and reprint requests to Dr. Joseph E. Gaugler, Ph.D., School of Nursing, University of Minnesota, 6-153 Weaver-Densford Hall, 1331, 308 Harvard Street S.E., Minneapolis, MN 55455. e-mail: [email protected] c 2011 American Association for Geriatric Psychiatry DOI: 10.1097/JGP.0b013e31820d92cc
Am J Geriatr Psychiatry 19:6, June 2011
497
Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
Does Caregiver Burden Mediate the Effects of Behavioral Disturbances
F
of factors among older persons leading to institutionalization, providing greater insight into the process of NHA.8 However, caregiving indices were not considered. A cross-sectional path analysis of desire to institutionalize found that role overload (feelings of being overwhelmed with care responsibilities) influenced the relationship between role performance and potential decisions to institutionalize among spousal Alzheimer disease caregivers.9 Other analyses of institutionalization have examined statistical interactions between various predictors, such as race, gender, functional status of the care recipient, and caregiver’s kin relationship to the person with dementia.10–13 While prior literature reviews and other studies have often emphasized that caregiver burden is at least equal to, if not more influential than, the indices of dementia severity when predicting institutionalization,1–3 little research has examined how burden and dementia symptoms (such as behavioral disturbances) interact to result in institutionalization. The few studies that considered morecomplex prediction models of NHA often examined interactions between variables, or moderator relationships. A moderator variable can specify when or under which conditions a particular effect occurs (i.e., the varying levels of a moderator variable change the strength of effect between an independent and dependent variable). However, as posited in conceptual models of dementia caregiving (e.g., the stress process model), subjective and/or emotional appraisals of behavioral disturbances potentially mediate the latter’s relationship with key clinical outcomes in dementia such as NHA.14,15 Mediators are those variables that account for the empirical association between two other variables. As Kraemer et al.16 and others note (see p 849), a mediator occurs in a causal pathway between a given independent and dependent variable. The mediator influences or causes an outcome to vary; in addition, the independent variable causes the mediator to vary.16 For this reason, mediators examine the process through which one variable influences another. If a variable, such as burden, fully mediates the relationship between a behavioral disturbance and time to NHA over time, the behavioral disturbance would no longer have a statistically significant relationship on time to NHA after the consideration of burden as a mediator. It is also possible that burden may
498
Am J Geriatr Psychiatry 19:6, June 2011
actors that lead to nursing home admission (NHA) have continued to receive attention in geriatric research because of the pressure to design and target clinical interventions to delay institutionalization and reduce potential costs.1–3 One salient predictor of NHA is dementia (i.e., Alzheimer disease or a related disorder). Studies of persons with dementia identify symptoms (e.g., occurrence of behavior problems) and family caregiving burden (feelings of social and emotional distress due to care demands) as potential predictors of time to NHA. However, an ongoing limitation in research that attempts to predict NHA is a lack of understanding of how potential predictors interact with or mediate each other. Such insights would prove useful clinically. Understanding how caregiving burden mediates the predictive relationship between behavior problems and time to NHA may enhance the delivery of interventions to delay institutionalization in dementia. Prior literature reviews emphasize the importance of severity of cognitive impairment or the presence of dementia in predicting institutionalization.1–3 Syntheses of research within dementia-specific samples identify several additional factors that are associated with NHA. For example, more-frequent occurrence of behavior problems (often operationalized as a summary score of item responses) are more likely to result in nursing home (NH) placement for persons with dementia.1 While most prior studies examine cumulative scores of behavior problems, specific behavioral disturbances, such as psychiatric symptoms and measures of agitation (hallucinations/delusions, wandering, and restlessness), are particularly critical in explaining NH placement.4–7 Measures of caregiving context also appear to make independent contributions to institutionalization. A comprehensive review of predictors of NHA in dementia found that among 16 studies that considered caregiver burden or a similar measure as a predictor, 11 reported a significant (p <0.05) and positive effect on institutionalization whereas 5 indicated a nonsignificant association.1 A noted limitation in prior research on predictors of NHA is that most studies include large groups of individual predictors, with little attention given to statistical interaction or whether certain indicators influence the relationships between key predictors and NHA. Exceptions include an earlier study that conducted a path analysis of the interrelation
Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
Joseph et al. partially mediate the predictive relationship between individual behavioral disturbances and time to NHA. In this scenario, the consideration of burden as a mediator would weaken, but not eliminate, the statistically significant empirical relationship between a behavior problem and institutionalization (see http://davidakenny.net/cm/mediate.htm#WIM for an illustration of mediation). A finding of burden as either a full or partial mediator would suggest the need for long-term psychosocial intervention models targeted at caregivers as opposed to solely patientfocused approaches (e.g., pharmacological interventions to manage behavior problems).17,18 The primary objective of this study was to determine whether caregiving burden mediated the relationship between specific behavior disturbances and time to NHA over a 3-year period in a multiregional sample of persons with dementia and their caregivers. We hypothesized that burden (the mediator) would account for and explain the empirical associations between individual behavioral disturbances (independent variables) and time to NHA (dependent variable).
METHODS The Medicare Alzheimer’s Disease Demonstration Evaluation The Medicare Alzheimer’s Disease Demonstration (MADDE) provided a Medicare-covered home care benefit and case management service for family caregivers of persons with dementia.19,20 The evaluation of MADDE relied on an experimental research design, with care recipients randomly assigned to either a treatment group eligible for the expanded Medicare case management benefit or a control group that did not receive the benefit. MADDE operated in eight communities between 1989 and 1994 (Champaign, IL; Cincinnati, OH; Memphis, TN; Miami, FL; Parkersburg, WV; Portland, OR; Rochester, NY; and Twin Cities, MN). The principal analysis of MADDE indicated that the expanded Medicare benefit had a main effect neither on time to NH placement for care recipients nor on caregiver burden or symptoms of depression.19,20 Due to the lack of treatment effects, both the treatment and control groups of MADDE were pooled for subsequent analyses. The large
Am J Geriatr Psychiatry 19:6, June 2011
sample size of dementia caregivers available in MADDE, the 3-year follow-up period, and inclusion of caregivers from multiple regions of the United States resulted in one of the most comprehensive data sources available about persons with dementia and their informal caregivers. The following criteria governed participants’ inclusion in MADDE: all older adults 1) had a physiciancertified diagnosis of an irreversible dementia; 2) were enrolled or eligible for parts A and B of Medicare; 3) had service needs; and 4) resided at home in one of the eight MADDE catchment areas. MADDE included persons with various causes of dementia, with 71% having a diagnosis of Alzheimer disease. The caregiver was the relative who provided the most assistance to the person with dementia throughout the course of MADDE. Individuals with dementia (i.e., care recipients) enrolled in the study over a 2-year period, and caregivers were administered in-person interviews by trained nurses and social workers every 6 months over 3 years. MADDE assessment interviews were conducted with the primary caregiver. The baseline interview was inperson, and semiannual assessments were conducted by telephone. The date of enrollment in MADDE was considered as the care recipient’s baseline date. Additional details on MADDE’s sources and process of referral, recruitment and selection, and definition of service needs are provided in the original articles describing the evaluation.19,20
Sample A total of 5,831 persons voluntarily enrolled in the program (evenly divided by treatment or control assignment) and received periodic assessments throughout the 3-year period of the demonstration. MADDE obtained institutionalization dates for stays that the caregiver reported as permanent. Any stays initially paid for by Medicare that ended in death (rather than discharge to the community) were also classified as permanent stays. These individuals were included in subsequent analyses. NH entry dates for short stays (i.e., >60 days) were compiled, but these stays were not counted as permanent NH days.19,20 Just more than 40% (43.9%; N = 2,556) of care recipients became permanently placed in an NH at some point during the demonstration.
499
Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
Does Caregiver Burden Mediate the Effects of Behavioral Disturbances Measures Behavior problems. Care recipient behavior problems, such as asking repetitive questions, being suspicious or accusative, or wandering/getting lost, were assessed on a 19-item version of the Memory and Behavior Problems Checklist (MBPC).21 The MBPC has shown appropriate reliability (via split-half and test–retest correlations, 0.65 and 0.80, respectively) and strong concurrent validity; predictive validity is also apparent when examining MBPC and its positive empirical relationship with NHA.1,22 The MBPC items were completed at each measurement interval via caregiver report (baseline Cronbach’s index of internal consistency, α = 0.78). Table 1 shows baseline frequencies of individual behavior problems. Burden. Burden was measured in MADDE with the 7-item short form of the Zarit Burden Inventory [(ZBI; baseline α = 0.89).23 The ZBI has demonstrated strong psychometric properties through its widespread use as a measure of caregiver stress in the dementia context. The ZBI was administered at each measurement interval. Response categories ranged from “never” (0) to “nearly always”4 (range: 0–28). To aid in interpretation, the scale was standardized by using the overall baseline mean and standard deviation for all analyses.
Key covariates. A number of preplacement covariates were selected on the basis of their demonstrated empirical relationships with burden and NHA in prior research.1,24 MADDE included measures of patient race or ethnicity, annual household income, formal education completed, living arrangement, home ownership, and source of insurance. Background characteristics of caregivers included age, kin relationship to the care recipient, education, employment status, duration of care, and whether there was a change of primary caregivers during the course of MADDE. To determine dementia severity in care recipients, MADDE case managers administered the Mini-Mental State Exam25 to care recipients at baseline (baseline α = 0.95). Measures of care recipients’ functional status included dependence on 10 activities of daily living (ADL) (baseline α = 0.92).26 A fixed list of options was used to measure service utilization (chore, personal care, and adult day care) and overnight hospital use. Other covariates included caregivers’ self-reported health status and caregivers’ own functional dependency, as measured by five ADLs (baseline α = 0.67) and eight instrumental ADLs ( baseline α = 0.82).27 Table 2 provides baseline descriptive data on key covariates and burden. Analysis
TABLE 1.
Baseline Behavioral Disturbances (N = 5,831)
Baseline Behavior Problem (Yes/No) Agitation Episodes of anger Constantly restless Constantly talkative Episodes of combativeness Danger to self Destroys property Danger to others Memory Forgets what day it is Loses or misplaces things Repetitive questions Trouble with recognition Leaves tasks uncompleted Relives past Wakes caregiver up at night Psychiatric symptoms Suspicious and accusative Hides things Thinks things are not there Does embarrassing things Wanders and gets lost
500
% 45.62 45.58 27.41 25.23 19.24 11.16 9.79 92.39 74.94 67.42 57.37 53.46 47.74 45.53 50.63 46.89 42.46 39.41 26.63
The primary research question focused on whether caregiver burden mediated the relationship between specific behavior disturbances and time to NHA. Time to NHA was operationalized as days from MADDE enrollment date (i.e., baseline) to reported institutionalization date. Since dementia caregivers enrolled in MADDE at various time points in their respective caregiving “careers” (i.e., due to care recipient dementia severity), it was important to control for key covariates that at least partially addressed this issue. For this reason, duration of care and other indices of dementia severity (see key covariates described previously) were empirically adjusted for all subsequent analytic models. Longitudinal measurements of dichotomous behavioral disturbances and a continuous measure of caregiver burden were collected every 6 months for 3 years or until one of the following occurred: NHA, death, or dropout. The three-step Baron and Kenny28 framework was used to examine the extent to which time-varying caregiver burden mediated
Am J Geriatr Psychiatry 19:6, June 2011
Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
Joseph et al.
TABLE 2.
Baseline Descriptive Information (N = 5,831)
Variable Care recipient age, y (%) 40–75 75–80 80–85 85 years and older Missing Care recipient is male subject (%) Care recipient race/ethnicity (%) Black White Hispanic Missing Care recipient educationa (%) Less than high school High school or greater Missing/refused Care recipient living arrangementa (%) Living alone Living with spouse/relative(s) Living with nonrelatives Care recipient home ownershipa (%) Rent Own Living with a relative at no charge Care recipient time in residence, moa Care recipient source of insurancea (%) Medicaid Health maintenance organization Veteran’s administration Retirement health plan Medigap Other Mini-Mental Status Exam (%) 0–10 (highest impairment) 10–20 20–23 23–30 (lowest impairment) Missing Care recipient activities of daily living dependenciesa Caregiver is spouse (%) Duration of care, moa (%) <12 12–24 24–48 >48 Missing Caregiver age, ya Caregiver educationa (%) Less than high school High school or greater Missing/refused Caregiver is employeda (%) Primary caregiver changed (%) Other caregiver provides assistancea (%) Service utilizationa (%) Chore In-home companion Adult day service
Am J Geriatr Psychiatry 19:6, June 2011
TABLE 2. (Continued) Variable
28.57 24.88 25.06 21.08 0.41 59.9 8.09 87.93 3.74 0.24 43.99 55.57 0.45
Personal care Hospital Zarit Burden Inventory total scorea Caregiver self-rated healtha (%) Excellent Good Fair Poor Refused/missing Caregiver functional status Activities of daily living dependenciesa Instrumental activities of daily living dependenciesa a Time-varying
13.62 80.28 6.11 17.39 47.93 34.68 M = 217.71, SD = 205.15 6.43 21.66 2.85 19.40 39.86 8.95 29.22 35.50 12.47 18.93 3.88 M = 3.83, SD = 2.83 49.10 7.63 15.23 28.88 34.01 14.25 M = 62.98, SD = 14.32 20.80 76.66 2.54 31.62 7.07 68.14 20.58 14.80 16.26 (Continued)
21.06 21.44 M = 12.54, SD = 6.38 28.57 46.12 19.26 3.60 2.45 M = 0.26, SD = 0.71 M = 0.84, SD = 1.55
covariate.
the relationship between time-varying behavioral disturbances and NHA, albeit here extended to the context of longitudinal-survival data (see also http://davidakenny.net/cm/mediate.htm). Step 1 established that behavioral disturbances were predictive of NHA using a Cox proportional hazards model, relating the time-varying behavioral disturbance with time to NHA treating deaths and dropouts as censored. Step 2 established that timevarying behavioral disturbances were predictive of the mediator, that is, caregiver burden, using longitudinal mixed-effect models, with each of the time-varying behavioral disturbance as a predictor of burden over time. The concurrent time behavioral disturbance was included in the longitudinal models, and a random person-specific intercept was used to control for correlation within individuals. Finally, step 3 established that caregiver burden mediated the predictive relationship between behavioral disturbance and NHA by including caregiver burden in the Cox proportional hazard model used in step 1. If the inclusion of time-varying caregiver burden resulted in a decreased empirical effect of each behavioral disturbance’s prediction of NHA, a conclusion of mediation was reached. Full mediation occurred when the introduction of the time-varying burden variable resulted in a statistically significant relationship between time-varying burden and time to NHA but a concurrent nonsignificant relationship between an individual behavior disturbance (the predictor) and time to NHA (see above and http://davidakenny.net/cm/mediate.htm#WIM).
501
Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
Does Caregiver Burden Mediate the Effects of Behavioral Disturbances All analyses utilized the full MADDE sample (N = 5,831). A bootstrapping method was used to establish whether the decrease in the behavioral disturbance effect between steps 1 and 3 was statistically significant.29 One hundred bootstrap samples were obtained and then the Cox models in steps 1 and 3 were refitted to each one. The difference between the two models in the log relative hazard for each behavior disturbance was calculated, and the distribution of this difference was used to obtain a p value for testing the null hypothesis of no difference. With one hundred bootstrap samples, a bootstrap p <0.01 (i.e., no more than 1 out of 100 bootstrap replicates showing no difference) would conservatively indicate a significant decrease at the α level of 0.05 (inflated from 0.01 due to Monte Carlo error in the bootstrap) in the log relative hazard when caregiver burden was included in the model (i.e., significant mediation). The Cox proportional hazards and longitudinal mixed models used for each step in testing
TABLE 3.
mediation were fitted separately for each of the 19 behavioral disturbances, including all baseline and time-varying covariates (Table 1). Behavioral disturbances were fitted separately to limit collinearity. For step 2, expected mean differences in standardized caregiver burden, standard errors, and associated p values are presented for each behavioral disturbance. For steps 1 and 3, hazard ratios are presented with 95% confidence intervals and associated p values. All analyses were performed in SAS 9.2 (SAS Institute, Inc., Cary, NC).
RESULTS Step 1 Test of Mediation Table 3 presents the results of time-varying behavioral disturbances’ effects on time to NHA controlling for key covariates (but not including caregiver burden) using the entire baseline MADDE sample (N = 5,831). All behavior problems demonstrated statistical significance and a positive association with time
Cox Proportional Hazards Model and Specific Behavioral Disturbances as Predictors of Time to Nursing Home Admission: With and Without Caregiver Burden (Steps 1 and 3 of Test for Mediation; N = 5,831) Without Caregiver Burden
Behavioral Disturbance Agitation Episodes of anger Constantly restless Constantly talkative Episodes of combativeness Dangerous to self Destroys property Dangerous to others Memory Forget what day it is Loses or misplaces things Repetitive questions Trouble with recognition Leaves tasks uncompleted Relives past Wakes caregiver up at night Psychiatric symptoms Suspicious and accusative Hides things Thinks things are not there Does embarrassing things Wanders and gets lost
Hazard Ratio Lower Upper for Burden CI CI
With Caregiver Burden pa
Hazard Ratio Lower Upper for Burden CI CI
pa
Hazard Ratio for Burden
pa
1.26 1.46 1.11 1.26 1.45 1.21 1.48
1.16 1.35 1.01 1.16 1.31 1.08 1.31
1.36 1.58 1.21 1.38 1.60 1.36 1.67
<0.0001 <0.0001 0.0249 <0.0001 <0.0001 0.0012 <0.0001
1.13 1.33 1.04 1.15 1.33 1.10 1.32
1.04 1.23 0.96 1.05 1.20 0.98 1.17
1.23 1.44 1.14 1.25 1.47 1.24 1.50
0.0034 <0.0001 0.346 0.0028 <0.0001 0.1082 <0.0001
1.24 1.22 1.26 1.25 1.24 1.26 1.25
<.0001 <.0001 <.0001 <.0001 <.0001 <.0001 <.0001
1.64 1.57 1.13 1.26 1.27 1.12 1.46
1.35 1.41 1.04 1.15 1.16 1.03 1.35
1.99 1.74 1.24 1.37 1.38 1.22 1.59
<0.0001 <0.0001 0.0062 <0.0001 <0.0001 0.0059 <0.0001
1.53 1.46 1.06 1.20 1.23 1.08 1.35
1.26 1.32 0.97 1.10 1.13 0.99 1.25
1.85 1.62 1.16 1.31 1.34 1.17 1.47
<0.0001 <0.0001 0.1913 <0.0001 <0.0001 0.0694 <0.0001
1.25 1.24 1.26 1.25 1.25 1.26 1.23
<.0001 <.0001 <.0001 <.0001 <.0001 <.0001 <.0001
1.23 1.44 1.57 1.34 1.38
1.14 1.33 1.45 1.24 1.26
1.34 1.57 1.70 1.45 1.51
<0.0001 <0.0001 <0.0001 <0.0001 <0.0001
1.13 1.35 1.47 1.20 1.30
1.04 1.24 1.36 1.10 1.19
1.23 1.47 1.59 1.31 1.42
0.0031 <0.0001 <0.0001 <0.0001 <0.0001
1.25 1.24 1.23 1.24 1.25
<.0001 <.0001 <.0001 <.0001 <.0001
Notes: Mediation due to caregiver burden is based on how much the hazard ratio decreases when caregiver burden is added to the model. Model also includes the covariates in Table 2; Comparing the confidence intervals (i.e., steps 1 and 3 of the mediational analysis) between models is inappropriate when testing change/reduction because the coefficients are highly correlated. CI: confidence interval. a p values are for the Wald χ 2 tests with 1 df testing each coefficient. .
502
Am J Geriatr Psychiatry 19:6, June 2011
Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
Joseph et al.
TABLE 4.
Longitudinal Model: Specific Behavioral Disturbances as Predictor of Caregiver Burden (Step 2 of Test for Mediation; N = 5,831)
Time-Varying Behavioral Disturbance Agitation Episodes of anger Constantly restless Constantly talkative Episodes of combativeness Dangerous to self Destroys property Dangerous to others Memory Forget what day it is Loses or misplaces things Repetitive questions Trouble with recognition Leaves tasks uncompleted Relives past Wakes caregiver up at night Psychiatric symptoms Suspicious and accusative Hides things Thinks things are not there Does embarrassing things Wanders and gets lost
Effect of Burden on Standardized Caregiver Burden
SE
p
0.35 0.31 0.20 0.31 0.27 0.28 0.34
0.01 0.01 0.01 0.01 0.02 0.02 0.02
<0.0001 <0.0001 <0.0001 <0.0001 <0.0001 <0.0001 <0.0001
0.19 0.21 0.23 0.15 0.09 0.16 0.28
0.02 0.02 0.01 0.01 0.01 0.01 0.01
<0.0001 <0.0001 <0.0001 <0.0001 <0.0001 <0.0001 <0.0001
0.28 0.25 0.27 0.35 0.19
0.01 0.01 0.01 0.01 0.01
<0.0001 <0.0001 <0.0001 <0.0001 <0.0001
Note: Model includes covariates in Table 2.
to NHA. The strongest behavioral predictors of time to NHA included the following: dangerous to self or others, forgets what day it is, loses or misplaces things, wakes caregiver up at night, hides things, and thinks things are not there. Step 2 Test of Mediation Table 4 demonstrates the time-varying empirical effects of individual behavioral disturbances on caregiver burden over the 3-year MADDE study period (N = 5,831). All behavior problems showed statistically significant positive effects on burden over time even after controlling for key covariates. The strongest individual predictors of burden over time were as follows: episodes of anger, episodes of restless and combativeness, dangerous to others, and does embarrassing things. Step 3 of Mediation Table 3 also illustrates the potential mediational effects of time-varying burden on time to NHA in the entire baseline sample (N = 5,831). The bootstrap tests
Am J Geriatr Psychiatry 19:6, June 2011
of mediation indicated that burden’s mediational effects were statistically significant (p <0.05) for all behavior problems included in the final model.29 As Table 3 implies, for most individual behavior problems, there was evidence of partial mediation, in which the individual behavior disturbance remained as a statistically significant predictor of institutionalization but the inclusion of burden appeared to weaken the empirical relationship between the individual behavioral disturbance and time to NHA. For example, as shown in the “Without Burden” column of Table 3, the reported episode of anger hazard ratio was 1.26; in the “With Burden” column of Table 3, the episode of anger hazard ratio dropped to 1.13. Similar reductions in the hazard ratios for all but four behavioral disturbances occurred, again suggesting the presence of burden’s partial mediation of the predictive relationship between these individual behavior problems and time to NHA. For four behavioral disturbances, however, burden fully mediated the relationship between the occurrence of a behavior problem and time to NHA (i.e., the inclusion of burden resulted in the behavior item no longer exerting a significant effect on institutionalization). These four behavioral disturbances were as follows: constantly talkative, destroys property, repetitive questions, and relives the past.
DISCUSSION The findings of this study suggest that burden either partially or fully mediated the effects of individual behavioral disturbances on institutionalization over time. In this regard, the findings lend support to stress process models,14,15 in which burden or similar measures are posited to mediate the relationships between care demands and key outcomes in dementia caregiving, such as NHA. However, the empirical findings here imply that this mediational relationship varies in potency across specific behavioral disturbances, suggesting the complexity of how individual behavioral disturbances, caregiving burden, and NHA operate over time. For most behavior problems, caregiver burden could be interpreted as a “partial” mediator. The influence of a specific behavioral disturbance on time to NHA was reduced and thus somewhat influenced by caregiver burden, but these behavior problems’ (including various
503
Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
Does Caregiver Burden Mediate the Effects of Behavioral Disturbances agitation, memory, and psychiatric behaviors) direct effects on the institutionalization event remained significant over time. Caregiver burden did fully mediate four behavior problems and their effects on time to NHA. Two of these items were types of agitation: combativeness and property destruction. During instances of these behavioral disruptions, it appeared that the decision to place the care recipient with dementia in an NH depended fully on caregivers’ perceptions of burden. For example, a care recipient who engaged in property destruction entered an NH during the 3-year course of the study largely due to how burdened the family caregiver felt. A similar mediational process occurred for select memory (repetitive questions) and psychiatric (relives past) symptoms. Overall, these findings highlight the multifaceted, diverse pathway to institutionalization for persons with dementia and their family caregivers, as the occurrence of behavior problems alone was not sufficient when considering NHA. Instead, the emotional context of dementia caregivers was pivotal to accounting for this outcome, suggesting that more complex conceptualizations of dementia caregiving, such as those specified in the stress process model,14,15 helped to clarify the manifestation of negative outcomes. As prior research has noted, analyses that include large numbers of variables as independent predictors of NH placement often have difficulty predicting NHA and do not effectively demonstrate how various predictors interact when influencing institutionalization. To some extent, the findings here address this analytical gap via the reliance on stress process conceptualizations of dementia caregiving. Several limitations are important to note. Because the parent data set was collected 15–17 years ago, it did not fully reflect the emergence of assisted living as a residential placement option for families.30 However, multiple reviews have found that some of the most prominent predictors of placement, such as frequency of behavior problems or caregiver stress, have remained as consistent predictions of NHA since this research first emerged.1 For these reasons and those described previously, the strengths of the MADDE data set justify its use. A related limitation was that the MBPC was updated after MADDE was initiated (e.g., the Revised MBPC).31 In addition, other assessments of dementia may provide more extensive information on the occurrence of psychotic or behavioral
504
symptoms and caregivers’ emotional reactions to specific behavioral disturbances. Although the MBPC has demonstrated strong psychometric properties,22 examining the individual items of the MBPC may have also increased the risk of measurement error as any examination of individual items (versus scaled measures) increases such risk. However, the simple yes/no item response option may have attenuated threats to measurement reliability. Another possible limitation of the current analysis is the lack of consistent information on other comorbid diseases that may have influenced time to NHA in persons with dementia. We attempted to control for functional dependencies via the use of ADL in the reported analyses. Single studies do report the influence of various diseases on NHA.32,33 For these reasons, there are possibly other predictors of NHA not available in MADDE that could have strengthened the overall consideration of covariates. The parent analyses and subsequent secondary analyses of MADDE found several variations across sites in sociodemographic characteristics and outcomes.19,34 In addition to variations in NH bed supply, long-term care support, and case management administration, other reasons for site diversity may have included historic events (e.g., Hurricane Andrew struck Florida during 1992 in the midst of the MADDE project). Site differences were particularly apparent for Florida. Due to the lack of site-level information (medical or social support infrastructures and sociopolitical or financial confounders), the reasons for such differences were difficult to address empirically in MADDE. The mediational properties of burden suggest clinical and research implications. The findings emphasize the need for multifaceted clinical interventions to assist dementia caregivers and persons with Alzheimer disease or a related dementia. Burden fully or partially mediated the relationship between individual behavior problems (such as items representing facets of memory, agitation, night-time awakening, psychiatric symptoms, and wandering) and time to institutionalization. This implies that intervention foci on both the caregiver and person with dementia are required to delay NHA. Many interventions that currently exist and are “best practice” exclusively target either the person with dementia or the caregiver (pharmacological or psychosocial protocols, respectively). By focusing on the process of
Am J Geriatr Psychiatry 19:6, June 2011
Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
Joseph et al. institutionalization (or, in this case, whether burden mediated the relationship between specific behavioral disturbances and NHA), the findings here may inspire a more-comprehensive treatment approach that incorporates the emotional needs of caregivers and the behavioral and/or psychiatric symptoms of the person with dementia in concert. For example, the occurrence of specific behavior disturbances such as severe agitation (e.g., combativeness) may require not only effective behavioral management of the person with dementia35,36 but also some kind of ongoing psychosocial consultation model that can alleviate caregivers’ perceptions of burden over time.17,18 In this manner, families who are at risk to institutionalize a relative with dementia can be more effectively targeted and served with up-to-date intervention plans. While various evidence-based protocols may report on the potential benefits of their intervention on the person with dementia and the family caregiver, it is less clear whether the clinical content of these protocols explicitly targets the needs of caregivers and persons with Alzheimer disease simultaneously.37 Future research efforts could provide a moredetailed analysis of how individuals enter NHs and how the wide array of individual predictors identified in extensive prior work interact with, moderate, or mediate each other as the entry event approaches. One ongoing issue in studies of dementia-specific
samples, as well as general older populations, is that while there are identifiable individual predictors, simply entering these variables side by side with little acknowledgment of endogeneity or the potentially complex longitudinal process that leads to NHA may not effectively predict entry (e.g., occurrence of a critical health event such as a fall, incontinence, or behavioral disturbance, which then may lead to caregiver overload, a desire to institutionalize, and eventual NHA). With the ongoing emphasis on designing more-effective pharmacological, psychosocial, or community-based service models to meet the various needs of chronically disabled clients, research that examines institutionalization as a process may better influence the structure and delivery of such interventions. This research was supported by a grant from the Eli Lilly Company to the School of Nursing, University of Minnesota (Total = $109,205; Dates: 28 May, 2009–30 April, 2010). This grant supported salary effort of Dr. Gaugler (principal investigator), Dr. Wall (coinvestigator), Dr. Kane (coinvestigator), and Mr. Menk (research assistant). Dr. Newcomer was consultant on this project. Dr. Sarsour, Dr. Johnston, and Dr. Schuh are the employees of the Global Health Outcomes Division of Eli Lilly and collaborated with the University of Minnesota research team in the conceptualization, interpretation, and dissemination of the findings reported in this article.
References 1. Gaugler JE, Yu F, Krichbaum K, et al: Predictors of nursing home admission for persons with dementia. Med Care 2009; 47: 191–198 2. Miller EA, Weissert WG: Predicting elderly people’s risk for nursing placement, hospitalization, functional impairment, and mortality: a synthesis. Med Care Res Rev 2000; 57:259–297 3. Gaugler JE, Duval S, Anderson KA, et al: Predicting nursing home admission in the U.S.: a meta-analysis. BMC Geriatr 2007; 7:13 4. Gilley DW, Bienias JL, Wilson RS, et al: Influence of behavioral symptoms on rates of institutionalization for persons with Alzheimer’s disease. Psychol Med 2004; 34:1129–1135 5. Wolstenholme J, Fenn P, Gray A, et al: Estimating the relationship between disease progression and cost of care in dementia. Br J Psychiatry 2002; 181:36–42 6. Gibbons LE, Teri L, Logsdon R, et al: Anxiety symptoms as predictors of nursing home placement in patients with Alzheimer’s disease. J Clin Geropsychol 2002; 8:335–342 7. Kasper JD, Shore AD: Cognitive impairment and problems behaviors as risk factors and institutionalization. J Appl Gerontol 1994; 13:371–385 8. Mohr RA: A causal modeling approach to institutionalization. Health Serv Manage Res 1994; 7:79–90
Am J Geriatr Psychiatry 19:6, June 2011
9. Mildonis MK, Smyth KA: How does disability and caregiver burden influence institutionalization in persons with dementia? Paper presented at: the Association for Health Services Management annual meeting, Washington, DC; June 21–23 1998:. . . 10. Akamigbo AB, Wolinsky FD: Reported expectations for nursing home placement among older adults and their role as risk factors for nursing home admissions. Gerontologist 2006; 46: 464–473 11. Smith GE, O’Brien PC, Ivnik RJ, et al: Prospective analysis of risk factors for nursing home placement of dementia patients. Neurol 2001; 57:1467–1473 12. Cho S, Zarit SH, Chiriboga DA: Wives and daughters: the differential role of day care use in the nursing home placement of cognitively impaired family members. Gerontologist 2009; 49: 57–67 13. Cagney KA, Agree EM: Racial differences in skilled nursing care and home health use: the mediating effects of family structure and social class. J Gerontol B Psychol Sci Soc Sci 1999; 54B: S223-S236 14. Pearlin LI, Mullan JT, Semple SJ, et al: Caregiving and the stress process: an overview of concepts and their measures. Gerontologist 1990; 30:583–594
505
Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
Does Caregiver Burden Mediate the Effects of Behavioral Disturbances 15. Aneshensel CS, Pearlin LI, Mullan JT, et al: Profiles in Caregiving: The Unexpected Career. San Diego, Academic Press, 1995 16. Kraemer HC, Wilson GT, Fairburn CG, et al: Mediators and moderators of treatment effects in randomized clinical trials. Arch Gen Psychiatry 2002; 59:877–883 17. Brodaty H, Mittelman M, Gibson L, et al: The effects of counseling spouse caregivers of people with Alzheimer disease taking Donepezil and of country of residence on rates of admission to nursing homes and mortality. Am J Geriatr Psychiatry 2009; 17:734–743 18. Mittelman MS, Brodaty H, Wallen AS, et al: A three-country randomized controlled trial of a psychosocial intervention for caregivers combined with pharmacological treatment for patients with Alzheimer disease: Effects on caregiver depression. Am J Geriatr Psychiatry 2008; 16:893–904 19. Newcomer R, Yordi C, DuNah R, et al: Effects of the Medicare Alzheimer’s Disease Demonstration on caregiver burden and depression. Health Serv Res 1999; 34:669–689 20. Miller R, Newcomer R, Fox P: Effects of the Medicare Alzheimer’s Disease Demonstration evaluation on nursing home entry. Health Serv Res 1999; 34:691–714 21. Zarit SH, Orr N, Zarit J: Understanding the stress of caregivers: planning an intervention, in Hidden Victims of Alzheimer’s Disease: Families Under Stress. Edited by Zarit SH, Orr N, Zarit J. New York, NYU Press, 1985, pp 69–86 22. Fischer J, Corcoran K: Measures for Clinical Practice and Research: A Sourcebook—Couples, Families, and Children. New York, Oxford University Press, 2007 23. Zarit SH, Reever KE, Bach-Peterson J: Relatives of the impaired elderly: correlates of feelings of burden. Gerontologist 1980; 20:649–655 24. Pinquart M, S¨ orensen S: Associations of caregiver stressors and uplifts with subjective well-being and depressive mood: a metaanalytic comparison. Aging Ment Health 2004; 8:438–449 25. Folstein MF, Folstein SE, McHugh PR: Mini-Mental State: a practical method for grading the cognitive state of patients for the clinician. J Psychiatr Res 1975; 12:189–198
506
26. Katz S, Ford AB, Moskowitz RW, et al: Studies of illness in the aged. The index of ADL: a standardized measure of biological and psychosocial function. JAMA 1963; 185:914–919 27. Lawton MP, Brody EM: Assessment of older people: selfmaintaining and instrumental activities of daily living. Gerontologist 1969; 9:179–186 28. Baron RM, Kenny DA: The moderator-mediator variable distinction in social psychological research: Conceptual, strategic, and statistical considerations. J Pers Soc Psychol 1986; 51:1173–1182 29. Shrout PE, Bolger N: Mediation in experimental and nonexperimental studies: new procedures and recommendations. Psychol Methods 2002; 7:422–445 30. Kane RA: Long-term care and a good quality of life: bringing them closer together. Gerontologist 2001; 41:293–304 31. Teri L, Truax P, Logsdon R, et al: Assessment of behavioral problems in dementia: the Revised Memory and Behavior Problems Checklist. Psychol Aging 1992; 7:622–631 32. Ahmed A, Ali M, Lefante CM, et al: Geriatric heart failure, depression, and nursing home admission: an observational study using propensity score analysis. Am J Geriatr Psychiatry 2006; 14: 867–875 33. Andrews AO, Bartels SJ, Xie H, et al: Increased risk of nursing home admission among middle aged and older adults with schizophrenia. Am J Geriatr Psychiatry 2009; 17:697–705 34. Gaugler JE, Mittelman MS, Hepburn K, et al: Predictors of change in caregiver burden and depressive symptoms following nursing home admission. Psychol Aging 2009; 24:385–396 35. Logsdon RG, McCurry SM, Teri L: Evidence-based psychological treatments for disruptive behaviors in individuals with dementia. Psychol Aging 2007; 22:28–36 36. Cohen-Mansfield J: Nonpharmacologic interventions for inappropriate behaviors in dementia: a review, summary, and critique. Am J Geriatr Psychiatry 2001; 9:361–381 37. Callahan CM, Boustani MA, Unverzagt FW, et al: Effectiveness of collaborative care for older adults with Alzheimer disease in primary care: a randomized controlled trial. JAMA 2006; 295: 2148–2157
Am J Geriatr Psychiatry 19:6, June 2011
Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
Does Caregiver Burden Mediate the Effects of Behavioral Disturbances on Nursing Home Admission? Joseph E. Gaugler, Ph.D., Melanie M. Wall, Ph.D., Robert L. Kane, M.D., Jeremiah S. Menk, M.S., Khaled Sarsour, Ph.D., Joseph A. Johnston, M.D., Kory Schuh, Ph.D., Robert Newcomer, Ph.D.
Objectives: The primary objective of this study was to determine whether caregiving burden mediated the relationship between specific behavior disturbances and time to nursing home admission (NHA) for persons with dementia (i.e., Alzheimer disease or a related disorder). Design: The study used secondary longitudinal data from the Medicare Alzheimer’s Disease Demonstration, a Medicare-covered home care benefit and case management program for family caregivers of persons with dementia. Primary caregivers of persons with dementia were assessed via in-person and telephone interviews every 6 months over a 3-year period. Setting: Dementia caregivers were recruited from eight catchment areas throughout the United States. Participants: The baseline sample included 5,831 dementia caregivers. Just more than 40% (43.9%; N = 2,556) of persons with dementia permanently entered a nursing home during the 3-year study period. Measurements: Individual behavior problems were measured with the Memory and Behavior Problem Checklist. Caregiving burden was assessed with a short version of the Zarit Burden Inventory. Key covariates, including sociodemographic background, functional status, and service utilization, were also considered. Results: Event history analyses revealed that time-varying measures of caregiver burden fully mediated the relationship between four behavioral disturbances (episodes of combativeness, property destruction, repetitive questions, and reliving the past) and NHA. Conclusions: The findings highlight the multifaceted, complex pathway to NHA for persons with dementia and their family caregivers. The results emphasize the need for comprehensive treatment approaches that incorporate the burden of caregivers and the behavioral/psychiatric symptoms of persons with dementia simultaneously. (Am J Geriatr Psychiatry 2011; 19:497–506)
Received April 5, 2010; revised October 12, 2010; accepted October 15, 2010. From the School of Nursing, Center on Aging (JEG), University of Minnesota, Minneapolis; Department of Biostatistics, Mailman School of Public Health (MMW), Columbia University, New York, NY; Division of Biostatistics (JSM) and Division of Health Policy and Management (RLK), School of Public Health, University of Minnesota, Minneapolis; Epidemiology and Health Services Research, Global Health Outcomes, Eli Lilly and Company, Indianapolis, IN (K. Sarsour, JAJ, K. Schuh); and Department of Social and Behavioral Science, University of California–San Francisco (RN). Send correspondence and reprint requests to Dr. Joseph E. Gaugler, Ph.D., School of Nursing, University of Minnesota, 6-153 Weaver-Densford Hall, 1331, 308 Harvard Street S.E., Minneapolis, MN 55455. e-mail: [email protected] c 2011 American Association for Geriatric Psychiatry DOI: 10.1097/JGP.0b013e31820d92cc
Am J Geriatr Psychiatry 19:6, June 2011
497
Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
Does Caregiver Burden Mediate the Effects of Behavioral Disturbances
F
of factors among older persons leading to institutionalization, providing greater insight into the process of NHA.8 However, caregiving indices were not considered. A cross-sectional path analysis of desire to institutionalize found that role overload (feelings of being overwhelmed with care responsibilities) influenced the relationship between role performance and potential decisions to institutionalize among spousal Alzheimer disease caregivers.9 Other analyses of institutionalization have examined statistical interactions between various predictors, such as race, gender, functional status of the care recipient, and caregiver’s kin relationship to the person with dementia.10–13 While prior literature reviews and other studies have often emphasized that caregiver burden is at least equal to, if not more influential than, the indices of dementia severity when predicting institutionalization,1–3 little research has examined how burden and dementia symptoms (such as behavioral disturbances) interact to result in institutionalization. The few studies that considered morecomplex prediction models of NHA often examined interactions between variables, or moderator relationships. A moderator variable can specify when or under which conditions a particular effect occurs (i.e., the varying levels of a moderator variable change the strength of effect between an independent and dependent variable). However, as posited in conceptual models of dementia caregiving (e.g., the stress process model), subjective and/or emotional appraisals of behavioral disturbances potentially mediate the latter’s relationship with key clinical outcomes in dementia such as NHA.14,15 Mediators are those variables that account for the empirical association between two other variables. As Kraemer et al.16 and others note (see p 849), a mediator occurs in a causal pathway between a given independent and dependent variable. The mediator influences or causes an outcome to vary; in addition, the independent variable causes the mediator to vary.16 For this reason, mediators examine the process through which one variable influences another. If a variable, such as burden, fully mediates the relationship between a behavioral disturbance and time to NHA over time, the behavioral disturbance would no longer have a statistically significant relationship on time to NHA after the consideration of burden as a mediator. It is also possible that burden may
498
Am J Geriatr Psychiatry 19:6, June 2011
actors that lead to nursing home admission (NHA) have continued to receive attention in geriatric research because of the pressure to design and target clinical interventions to delay institutionalization and reduce potential costs.1–3 One salient predictor of NHA is dementia (i.e., Alzheimer disease or a related disorder). Studies of persons with dementia identify symptoms (e.g., occurrence of behavior problems) and family caregiving burden (feelings of social and emotional distress due to care demands) as potential predictors of time to NHA. However, an ongoing limitation in research that attempts to predict NHA is a lack of understanding of how potential predictors interact with or mediate each other. Such insights would prove useful clinically. Understanding how caregiving burden mediates the predictive relationship between behavior problems and time to NHA may enhance the delivery of interventions to delay institutionalization in dementia. Prior literature reviews emphasize the importance of severity of cognitive impairment or the presence of dementia in predicting institutionalization.1–3 Syntheses of research within dementia-specific samples identify several additional factors that are associated with NHA. For example, more-frequent occurrence of behavior problems (often operationalized as a summary score of item responses) are more likely to result in nursing home (NH) placement for persons with dementia.1 While most prior studies examine cumulative scores of behavior problems, specific behavioral disturbances, such as psychiatric symptoms and measures of agitation (hallucinations/delusions, wandering, and restlessness), are particularly critical in explaining NH placement.4–7 Measures of caregiving context also appear to make independent contributions to institutionalization. A comprehensive review of predictors of NHA in dementia found that among 16 studies that considered caregiver burden or a similar measure as a predictor, 11 reported a significant (p <0.05) and positive effect on institutionalization whereas 5 indicated a nonsignificant association.1 A noted limitation in prior research on predictors of NHA is that most studies include large groups of individual predictors, with little attention given to statistical interaction or whether certain indicators influence the relationships between key predictors and NHA. Exceptions include an earlier study that conducted a path analysis of the interrelation
Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
Joseph et al. partially mediate the predictive relationship between individual behavioral disturbances and time to NHA. In this scenario, the consideration of burden as a mediator would weaken, but not eliminate, the statistically significant empirical relationship between a behavior problem and institutionalization (see http://davidakenny.net/cm/mediate.htm#WIM for an illustration of mediation). A finding of burden as either a full or partial mediator would suggest the need for long-term psychosocial intervention models targeted at caregivers as opposed to solely patientfocused approaches (e.g., pharmacological interventions to manage behavior problems).17,18 The primary objective of this study was to determine whether caregiving burden mediated the relationship between specific behavior disturbances and time to NHA over a 3-year period in a multiregional sample of persons with dementia and their caregivers. We hypothesized that burden (the mediator) would account for and explain the empirical associations between individual behavioral disturbances (independent variables) and time to NHA (dependent variable).
METHODS The Medicare Alzheimer’s Disease Demonstration Evaluation The Medicare Alzheimer’s Disease Demonstration (MADDE) provided a Medicare-covered home care benefit and case management service for family caregivers of persons with dementia.19,20 The evaluation of MADDE relied on an experimental research design, with care recipients randomly assigned to either a treatment group eligible for the expanded Medicare case management benefit or a control group that did not receive the benefit. MADDE operated in eight communities between 1989 and 1994 (Champaign, IL; Cincinnati, OH; Memphis, TN; Miami, FL; Parkersburg, WV; Portland, OR; Rochester, NY; and Twin Cities, MN). The principal analysis of MADDE indicated that the expanded Medicare benefit had a main effect neither on time to NH placement for care recipients nor on caregiver burden or symptoms of depression.19,20 Due to the lack of treatment effects, both the treatment and control groups of MADDE were pooled for subsequent analyses. The large
Am J Geriatr Psychiatry 19:6, June 2011
sample size of dementia caregivers available in MADDE, the 3-year follow-up period, and inclusion of caregivers from multiple regions of the United States resulted in one of the most comprehensive data sources available about persons with dementia and their informal caregivers. The following criteria governed participants’ inclusion in MADDE: all older adults 1) had a physiciancertified diagnosis of an irreversible dementia; 2) were enrolled or eligible for parts A and B of Medicare; 3) had service needs; and 4) resided at home in one of the eight MADDE catchment areas. MADDE included persons with various causes of dementia, with 71% having a diagnosis of Alzheimer disease. The caregiver was the relative who provided the most assistance to the person with dementia throughout the course of MADDE. Individuals with dementia (i.e., care recipients) enrolled in the study over a 2-year period, and caregivers were administered in-person interviews by trained nurses and social workers every 6 months over 3 years. MADDE assessment interviews were conducted with the primary caregiver. The baseline interview was inperson, and semiannual assessments were conducted by telephone. The date of enrollment in MADDE was considered as the care recipient’s baseline date. Additional details on MADDE’s sources and process of referral, recruitment and selection, and definition of service needs are provided in the original articles describing the evaluation.19,20
Sample A total of 5,831 persons voluntarily enrolled in the program (evenly divided by treatment or control assignment) and received periodic assessments throughout the 3-year period of the demonstration. MADDE obtained institutionalization dates for stays that the caregiver reported as permanent. Any stays initially paid for by Medicare that ended in death (rather than discharge to the community) were also classified as permanent stays. These individuals were included in subsequent analyses. NH entry dates for short stays (i.e., >60 days) were compiled, but these stays were not counted as permanent NH days.19,20 Just more than 40% (43.9%; N = 2,556) of care recipients became permanently placed in an NH at some point during the demonstration.
499
Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
Does Caregiver Burden Mediate the Effects of Behavioral Disturbances Measures Behavior problems. Care recipient behavior problems, such as asking repetitive questions, being suspicious or accusative, or wandering/getting lost, were assessed on a 19-item version of the Memory and Behavior Problems Checklist (MBPC).21 The MBPC has shown appropriate reliability (via split-half and test–retest correlations, 0.65 and 0.80, respectively) and strong concurrent validity; predictive validity is also apparent when examining MBPC and its positive empirical relationship with NHA.1,22 The MBPC items were completed at each measurement interval via caregiver report (baseline Cronbach’s index of internal consistency, α = 0.78). Table 1 shows baseline frequencies of individual behavior problems. Burden. Burden was measured in MADDE with the 7-item short form of the Zarit Burden Inventory [(ZBI; baseline α = 0.89).23 The ZBI has demonstrated strong psychometric properties through its widespread use as a measure of caregiver stress in the dementia context. The ZBI was administered at each measurement interval. Response categories ranged from “never” (0) to “nearly always”4 (range: 0–28). To aid in interpretation, the scale was standardized by using the overall baseline mean and standard deviation for all analyses.
Key covariates. A number of preplacement covariates were selected on the basis of their demonstrated empirical relationships with burden and NHA in prior research.1,24 MADDE included measures of patient race or ethnicity, annual household income, formal education completed, living arrangement, home ownership, and source of insurance. Background characteristics of caregivers included age, kin relationship to the care recipient, education, employment status, duration of care, and whether there was a change of primary caregivers during the course of MADDE. To determine dementia severity in care recipients, MADDE case managers administered the Mini-Mental State Exam25 to care recipients at baseline (baseline α = 0.95). Measures of care recipients’ functional status included dependence on 10 activities of daily living (ADL) (baseline α = 0.92).26 A fixed list of options was used to measure service utilization (chore, personal care, and adult day care) and overnight hospital use. Other covariates included caregivers’ self-reported health status and caregivers’ own functional dependency, as measured by five ADLs (baseline α = 0.67) and eight instrumental ADLs ( baseline α = 0.82).27 Table 2 provides baseline descriptive data on key covariates and burden. Analysis
TABLE 1.
Baseline Behavioral Disturbances (N = 5,831)
Baseline Behavior Problem (Yes/No) Agitation Episodes of anger Constantly restless Constantly talkative Episodes of combativeness Danger to self Destroys property Danger to others Memory Forgets what day it is Loses or misplaces things Repetitive questions Trouble with recognition Leaves tasks uncompleted Relives past Wakes caregiver up at night Psychiatric symptoms Suspicious and accusative Hides things Thinks things are not there Does embarrassing things Wanders and gets lost
500
% 45.62 45.58 27.41 25.23 19.24 11.16 9.79 92.39 74.94 67.42 57.37 53.46 47.74 45.53 50.63 46.89 42.46 39.41 26.63
The primary research question focused on whether caregiver burden mediated the relationship between specific behavior disturbances and time to NHA. Time to NHA was operationalized as days from MADDE enrollment date (i.e., baseline) to reported institutionalization date. Since dementia caregivers enrolled in MADDE at various time points in their respective caregiving “careers” (i.e., due to care recipient dementia severity), it was important to control for key covariates that at least partially addressed this issue. For this reason, duration of care and other indices of dementia severity (see key covariates described previously) were empirically adjusted for all subsequent analytic models. Longitudinal measurements of dichotomous behavioral disturbances and a continuous measure of caregiver burden were collected every 6 months for 3 years or until one of the following occurred: NHA, death, or dropout. The three-step Baron and Kenny28 framework was used to examine the extent to which time-varying caregiver burden mediated
Am J Geriatr Psychiatry 19:6, June 2011
Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
Joseph et al.
TABLE 2.
Baseline Descriptive Information (N = 5,831)
Variable Care recipient age, y (%) 40–75 75–80 80–85 85 years and older Missing Care recipient is male subject (%) Care recipient race/ethnicity (%) Black White Hispanic Missing Care recipient educationa (%) Less than high school High school or greater Missing/refused Care recipient living arrangementa (%) Living alone Living with spouse/relative(s) Living with nonrelatives Care recipient home ownershipa (%) Rent Own Living with a relative at no charge Care recipient time in residence, moa Care recipient source of insurancea (%) Medicaid Health maintenance organization Veteran’s administration Retirement health plan Medigap Other Mini-Mental Status Exam (%) 0–10 (highest impairment) 10–20 20–23 23–30 (lowest impairment) Missing Care recipient activities of daily living dependenciesa Caregiver is spouse (%) Duration of care, moa (%) <12 12–24 24–48 >48 Missing Caregiver age, ya Caregiver educationa (%) Less than high school High school or greater Missing/refused Caregiver is employeda (%) Primary caregiver changed (%) Other caregiver provides assistancea (%) Service utilizationa (%) Chore In-home companion Adult day service
Am J Geriatr Psychiatry 19:6, June 2011
TABLE 2. (Continued) Variable
28.57 24.88 25.06 21.08 0.41 59.9 8.09 87.93 3.74 0.24 43.99 55.57 0.45
Personal care Hospital Zarit Burden Inventory total scorea Caregiver self-rated healtha (%) Excellent Good Fair Poor Refused/missing Caregiver functional status Activities of daily living dependenciesa Instrumental activities of daily living dependenciesa a Time-varying
13.62 80.28 6.11 17.39 47.93 34.68 M = 217.71, SD = 205.15 6.43 21.66 2.85 19.40 39.86 8.95 29.22 35.50 12.47 18.93 3.88 M = 3.83, SD = 2.83 49.10 7.63 15.23 28.88 34.01 14.25 M = 62.98, SD = 14.32 20.80 76.66 2.54 31.62 7.07 68.14 20.58 14.80 16.26 (Continued)
21.06 21.44 M = 12.54, SD = 6.38 28.57 46.12 19.26 3.60 2.45 M = 0.26, SD = 0.71 M = 0.84, SD = 1.55
covariate.
the relationship between time-varying behavioral disturbances and NHA, albeit here extended to the context of longitudinal-survival data (see also http://davidakenny.net/cm/mediate.htm). Step 1 established that behavioral disturbances were predictive of NHA using a Cox proportional hazards model, relating the time-varying behavioral disturbance with time to NHA treating deaths and dropouts as censored. Step 2 established that timevarying behavioral disturbances were predictive of the mediator, that is, caregiver burden, using longitudinal mixed-effect models, with each of the time-varying behavioral disturbance as a predictor of burden over time. The concurrent time behavioral disturbance was included in the longitudinal models, and a random person-specific intercept was used to control for correlation within individuals. Finally, step 3 established that caregiver burden mediated the predictive relationship between behavioral disturbance and NHA by including caregiver burden in the Cox proportional hazard model used in step 1. If the inclusion of time-varying caregiver burden resulted in a decreased empirical effect of each behavioral disturbance’s prediction of NHA, a conclusion of mediation was reached. Full mediation occurred when the introduction of the time-varying burden variable resulted in a statistically significant relationship between time-varying burden and time to NHA but a concurrent nonsignificant relationship between an individual behavior disturbance (the predictor) and time to NHA (see above and http://davidakenny.net/cm/mediate.htm#WIM).
501
Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
Does Caregiver Burden Mediate the Effects of Behavioral Disturbances All analyses utilized the full MADDE sample (N = 5,831). A bootstrapping method was used to establish whether the decrease in the behavioral disturbance effect between steps 1 and 3 was statistically significant.29 One hundred bootstrap samples were obtained and then the Cox models in steps 1 and 3 were refitted to each one. The difference between the two models in the log relative hazard for each behavior disturbance was calculated, and the distribution of this difference was used to obtain a p value for testing the null hypothesis of no difference. With one hundred bootstrap samples, a bootstrap p <0.01 (i.e., no more than 1 out of 100 bootstrap replicates showing no difference) would conservatively indicate a significant decrease at the α level of 0.05 (inflated from 0.01 due to Monte Carlo error in the bootstrap) in the log relative hazard when caregiver burden was included in the model (i.e., significant mediation). The Cox proportional hazards and longitudinal mixed models used for each step in testing
TABLE 3.
mediation were fitted separately for each of the 19 behavioral disturbances, including all baseline and time-varying covariates (Table 1). Behavioral disturbances were fitted separately to limit collinearity. For step 2, expected mean differences in standardized caregiver burden, standard errors, and associated p values are presented for each behavioral disturbance. For steps 1 and 3, hazard ratios are presented with 95% confidence intervals and associated p values. All analyses were performed in SAS 9.2 (SAS Institute, Inc., Cary, NC).
RESULTS Step 1 Test of Mediation Table 3 presents the results of time-varying behavioral disturbances’ effects on time to NHA controlling for key covariates (but not including caregiver burden) using the entire baseline MADDE sample (N = 5,831). All behavior problems demonstrated statistical significance and a positive association with time
Cox Proportional Hazards Model and Specific Behavioral Disturbances as Predictors of Time to Nursing Home Admission: With and Without Caregiver Burden (Steps 1 and 3 of Test for Mediation; N = 5,831) Without Caregiver Burden
Behavioral Disturbance Agitation Episodes of anger Constantly restless Constantly talkative Episodes of combativeness Dangerous to self Destroys property Dangerous to others Memory Forget what day it is Loses or misplaces things Repetitive questions Trouble with recognition Leaves tasks uncompleted Relives past Wakes caregiver up at night Psychiatric symptoms Suspicious and accusative Hides things Thinks things are not there Does embarrassing things Wanders and gets lost
Hazard Ratio Lower Upper for Burden CI CI
With Caregiver Burden pa
Hazard Ratio Lower Upper for Burden CI CI
pa
Hazard Ratio for Burden
pa
1.26 1.46 1.11 1.26 1.45 1.21 1.48
1.16 1.35 1.01 1.16 1.31 1.08 1.31
1.36 1.58 1.21 1.38 1.60 1.36 1.67
<0.0001 <0.0001 0.0249 <0.0001 <0.0001 0.0012 <0.0001
1.13 1.33 1.04 1.15 1.33 1.10 1.32
1.04 1.23 0.96 1.05 1.20 0.98 1.17
1.23 1.44 1.14 1.25 1.47 1.24 1.50
0.0034 <0.0001 0.346 0.0028 <0.0001 0.1082 <0.0001
1.24 1.22 1.26 1.25 1.24 1.26 1.25
<.0001 <.0001 <.0001 <.0001 <.0001 <.0001 <.0001
1.64 1.57 1.13 1.26 1.27 1.12 1.46
1.35 1.41 1.04 1.15 1.16 1.03 1.35
1.99 1.74 1.24 1.37 1.38 1.22 1.59
<0.0001 <0.0001 0.0062 <0.0001 <0.0001 0.0059 <0.0001
1.53 1.46 1.06 1.20 1.23 1.08 1.35
1.26 1.32 0.97 1.10 1.13 0.99 1.25
1.85 1.62 1.16 1.31 1.34 1.17 1.47
<0.0001 <0.0001 0.1913 <0.0001 <0.0001 0.0694 <0.0001
1.25 1.24 1.26 1.25 1.25 1.26 1.23
<.0001 <.0001 <.0001 <.0001 <.0001 <.0001 <.0001
1.23 1.44 1.57 1.34 1.38
1.14 1.33 1.45 1.24 1.26
1.34 1.57 1.70 1.45 1.51
<0.0001 <0.0001 <0.0001 <0.0001 <0.0001
1.13 1.35 1.47 1.20 1.30
1.04 1.24 1.36 1.10 1.19
1.23 1.47 1.59 1.31 1.42
0.0031 <0.0001 <0.0001 <0.0001 <0.0001
1.25 1.24 1.23 1.24 1.25
<.0001 <.0001 <.0001 <.0001 <.0001
Notes: Mediation due to caregiver burden is based on how much the hazard ratio decreases when caregiver burden is added to the model. Model also includes the covariates in Table 2; Comparing the confidence intervals (i.e., steps 1 and 3 of the mediational analysis) between models is inappropriate when testing change/reduction because the coefficients are highly correlated. CI: confidence interval. a p values are for the Wald χ 2 tests with 1 df testing each coefficient. .
502
Am J Geriatr Psychiatry 19:6, June 2011
Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
Joseph et al.
TABLE 4.
Longitudinal Model: Specific Behavioral Disturbances as Predictor of Caregiver Burden (Step 2 of Test for Mediation; N = 5,831)
Time-Varying Behavioral Disturbance Agitation Episodes of anger Constantly restless Constantly talkative Episodes of combativeness Dangerous to self Destroys property Dangerous to others Memory Forget what day it is Loses or misplaces things Repetitive questions Trouble with recognition Leaves tasks uncompleted Relives past Wakes caregiver up at night Psychiatric symptoms Suspicious and accusative Hides things Thinks things are not there Does embarrassing things Wanders and gets lost
Effect of Burden on Standardized Caregiver Burden
SE
p
0.35 0.31 0.20 0.31 0.27 0.28 0.34
0.01 0.01 0.01 0.01 0.02 0.02 0.02
<0.0001 <0.0001 <0.0001 <0.0001 <0.0001 <0.0001 <0.0001
0.19 0.21 0.23 0.15 0.09 0.16 0.28
0.02 0.02 0.01 0.01 0.01 0.01 0.01
<0.0001 <0.0001 <0.0001 <0.0001 <0.0001 <0.0001 <0.0001
0.28 0.25 0.27 0.35 0.19
0.01 0.01 0.01 0.01 0.01
<0.0001 <0.0001 <0.0001 <0.0001 <0.0001
Note: Model includes covariates in Table 2.
to NHA. The strongest behavioral predictors of time to NHA included the following: dangerous to self or others, forgets what day it is, loses or misplaces things, wakes caregiver up at night, hides things, and thinks things are not there. Step 2 Test of Mediation Table 4 demonstrates the time-varying empirical effects of individual behavioral disturbances on caregiver burden over the 3-year MADDE study period (N = 5,831). All behavior problems showed statistically significant positive effects on burden over time even after controlling for key covariates. The strongest individual predictors of burden over time were as follows: episodes of anger, episodes of restless and combativeness, dangerous to others, and does embarrassing things. Step 3 of Mediation Table 3 also illustrates the potential mediational effects of time-varying burden on time to NHA in the entire baseline sample (N = 5,831). The bootstrap tests
Am J Geriatr Psychiatry 19:6, June 2011
of mediation indicated that burden’s mediational effects were statistically significant (p <0.05) for all behavior problems included in the final model.29 As Table 3 implies, for most individual behavior problems, there was evidence of partial mediation, in which the individual behavior disturbance remained as a statistically significant predictor of institutionalization but the inclusion of burden appeared to weaken the empirical relationship between the individual behavioral disturbance and time to NHA. For example, as shown in the “Without Burden” column of Table 3, the reported episode of anger hazard ratio was 1.26; in the “With Burden” column of Table 3, the episode of anger hazard ratio dropped to 1.13. Similar reductions in the hazard ratios for all but four behavioral disturbances occurred, again suggesting the presence of burden’s partial mediation of the predictive relationship between these individual behavior problems and time to NHA. For four behavioral disturbances, however, burden fully mediated the relationship between the occurrence of a behavior problem and time to NHA (i.e., the inclusion of burden resulted in the behavior item no longer exerting a significant effect on institutionalization). These four behavioral disturbances were as follows: constantly talkative, destroys property, repetitive questions, and relives the past.
DISCUSSION The findings of this study suggest that burden either partially or fully mediated the effects of individual behavioral disturbances on institutionalization over time. In this regard, the findings lend support to stress process models,14,15 in which burden or similar measures are posited to mediate the relationships between care demands and key outcomes in dementia caregiving, such as NHA. However, the empirical findings here imply that this mediational relationship varies in potency across specific behavioral disturbances, suggesting the complexity of how individual behavioral disturbances, caregiving burden, and NHA operate over time. For most behavior problems, caregiver burden could be interpreted as a “partial” mediator. The influence of a specific behavioral disturbance on time to NHA was reduced and thus somewhat influenced by caregiver burden, but these behavior problems’ (including various
503
Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
Does Caregiver Burden Mediate the Effects of Behavioral Disturbances agitation, memory, and psychiatric behaviors) direct effects on the institutionalization event remained significant over time. Caregiver burden did fully mediate four behavior problems and their effects on time to NHA. Two of these items were types of agitation: combativeness and property destruction. During instances of these behavioral disruptions, it appeared that the decision to place the care recipient with dementia in an NH depended fully on caregivers’ perceptions of burden. For example, a care recipient who engaged in property destruction entered an NH during the 3-year course of the study largely due to how burdened the family caregiver felt. A similar mediational process occurred for select memory (repetitive questions) and psychiatric (relives past) symptoms. Overall, these findings highlight the multifaceted, diverse pathway to institutionalization for persons with dementia and their family caregivers, as the occurrence of behavior problems alone was not sufficient when considering NHA. Instead, the emotional context of dementia caregivers was pivotal to accounting for this outcome, suggesting that more complex conceptualizations of dementia caregiving, such as those specified in the stress process model,14,15 helped to clarify the manifestation of negative outcomes. As prior research has noted, analyses that include large numbers of variables as independent predictors of NH placement often have difficulty predicting NHA and do not effectively demonstrate how various predictors interact when influencing institutionalization. To some extent, the findings here address this analytical gap via the reliance on stress process conceptualizations of dementia caregiving. Several limitations are important to note. Because the parent data set was collected 15–17 years ago, it did not fully reflect the emergence of assisted living as a residential placement option for families.30 However, multiple reviews have found that some of the most prominent predictors of placement, such as frequency of behavior problems or caregiver stress, have remained as consistent predictions of NHA since this research first emerged.1 For these reasons and those described previously, the strengths of the MADDE data set justify its use. A related limitation was that the MBPC was updated after MADDE was initiated (e.g., the Revised MBPC).31 In addition, other assessments of dementia may provide more extensive information on the occurrence of psychotic or behavioral
504
symptoms and caregivers’ emotional reactions to specific behavioral disturbances. Although the MBPC has demonstrated strong psychometric properties,22 examining the individual items of the MBPC may have also increased the risk of measurement error as any examination of individual items (versus scaled measures) increases such risk. However, the simple yes/no item response option may have attenuated threats to measurement reliability. Another possible limitation of the current analysis is the lack of consistent information on other comorbid diseases that may have influenced time to NHA in persons with dementia. We attempted to control for functional dependencies via the use of ADL in the reported analyses. Single studies do report the influence of various diseases on NHA.32,33 For these reasons, there are possibly other predictors of NHA not available in MADDE that could have strengthened the overall consideration of covariates. The parent analyses and subsequent secondary analyses of MADDE found several variations across sites in sociodemographic characteristics and outcomes.19,34 In addition to variations in NH bed supply, long-term care support, and case management administration, other reasons for site diversity may have included historic events (e.g., Hurricane Andrew struck Florida during 1992 in the midst of the MADDE project). Site differences were particularly apparent for Florida. Due to the lack of site-level information (medical or social support infrastructures and sociopolitical or financial confounders), the reasons for such differences were difficult to address empirically in MADDE. The mediational properties of burden suggest clinical and research implications. The findings emphasize the need for multifaceted clinical interventions to assist dementia caregivers and persons with Alzheimer disease or a related dementia. Burden fully or partially mediated the relationship between individual behavior problems (such as items representing facets of memory, agitation, night-time awakening, psychiatric symptoms, and wandering) and time to institutionalization. This implies that intervention foci on both the caregiver and person with dementia are required to delay NHA. Many interventions that currently exist and are “best practice” exclusively target either the person with dementia or the caregiver (pharmacological or psychosocial protocols, respectively). By focusing on the process of
Am J Geriatr Psychiatry 19:6, June 2011
Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
Joseph et al. institutionalization (or, in this case, whether burden mediated the relationship between specific behavioral disturbances and NHA), the findings here may inspire a more-comprehensive treatment approach that incorporates the emotional needs of caregivers and the behavioral and/or psychiatric symptoms of the person with dementia in concert. For example, the occurrence of specific behavior disturbances such as severe agitation (e.g., combativeness) may require not only effective behavioral management of the person with dementia35,36 but also some kind of ongoing psychosocial consultation model that can alleviate caregivers’ perceptions of burden over time.17,18 In this manner, families who are at risk to institutionalize a relative with dementia can be more effectively targeted and served with up-to-date intervention plans. While various evidence-based protocols may report on the potential benefits of their intervention on the person with dementia and the family caregiver, it is less clear whether the clinical content of these protocols explicitly targets the needs of caregivers and persons with Alzheimer disease simultaneously.37 Future research efforts could provide a moredetailed analysis of how individuals enter NHs and how the wide array of individual predictors identified in extensive prior work interact with, moderate, or mediate each other as the entry event approaches. One ongoing issue in studies of dementia-specific
samples, as well as general older populations, is that while there are identifiable individual predictors, simply entering these variables side by side with little acknowledgment of endogeneity or the potentially complex longitudinal process that leads to NHA may not effectively predict entry (e.g., occurrence of a critical health event such as a fall, incontinence, or behavioral disturbance, which then may lead to caregiver overload, a desire to institutionalize, and eventual NHA). With the ongoing emphasis on designing more-effective pharmacological, psychosocial, or community-based service models to meet the various needs of chronically disabled clients, research that examines institutionalization as a process may better influence the structure and delivery of such interventions. This research was supported by a grant from the Eli Lilly Company to the School of Nursing, University of Minnesota (Total = $109,205; Dates: 28 May, 2009–30 April, 2010). This grant supported salary effort of Dr. Gaugler (principal investigator), Dr. Wall (coinvestigator), Dr. Kane (coinvestigator), and Mr. Menk (research assistant). Dr. Newcomer was consultant on this project. Dr. Sarsour, Dr. Johnston, and Dr. Schuh are the employees of the Global Health Outcomes Division of Eli Lilly and collaborated with the University of Minnesota research team in the conceptualization, interpretation, and dissemination of the findings reported in this article.
References 1. Gaugler JE, Yu F, Krichbaum K, et al: Predictors of nursing home admission for persons with dementia. Med Care 2009; 47: 191–198 2. Miller EA, Weissert WG: Predicting elderly people’s risk for nursing placement, hospitalization, functional impairment, and mortality: a synthesis. Med Care Res Rev 2000; 57:259–297 3. Gaugler JE, Duval S, Anderson KA, et al: Predicting nursing home admission in the U.S.: a meta-analysis. BMC Geriatr 2007; 7:13 4. Gilley DW, Bienias JL, Wilson RS, et al: Influence of behavioral symptoms on rates of institutionalization for persons with Alzheimer’s disease. Psychol Med 2004; 34:1129–1135 5. Wolstenholme J, Fenn P, Gray A, et al: Estimating the relationship between disease progression and cost of care in dementia. Br J Psychiatry 2002; 181:36–42 6. Gibbons LE, Teri L, Logsdon R, et al: Anxiety symptoms as predictors of nursing home placement in patients with Alzheimer’s disease. J Clin Geropsychol 2002; 8:335–342 7. Kasper JD, Shore AD: Cognitive impairment and problems behaviors as risk factors and institutionalization. J Appl Gerontol 1994; 13:371–385 8. Mohr RA: A causal modeling approach to institutionalization. Health Serv Manage Res 1994; 7:79–90
Am J Geriatr Psychiatry 19:6, June 2011
9. Mildonis MK, Smyth KA: How does disability and caregiver burden influence institutionalization in persons with dementia? Paper presented at: the Association for Health Services Management annual meeting, Washington, DC; June 21–23 1998:. . . 10. Akamigbo AB, Wolinsky FD: Reported expectations for nursing home placement among older adults and their role as risk factors for nursing home admissions. Gerontologist 2006; 46: 464–473 11. Smith GE, O’Brien PC, Ivnik RJ, et al: Prospective analysis of risk factors for nursing home placement of dementia patients. Neurol 2001; 57:1467–1473 12. Cho S, Zarit SH, Chiriboga DA: Wives and daughters: the differential role of day care use in the nursing home placement of cognitively impaired family members. Gerontologist 2009; 49: 57–67 13. Cagney KA, Agree EM: Racial differences in skilled nursing care and home health use: the mediating effects of family structure and social class. J Gerontol B Psychol Sci Soc Sci 1999; 54B: S223-S236 14. Pearlin LI, Mullan JT, Semple SJ, et al: Caregiving and the stress process: an overview of concepts and their measures. Gerontologist 1990; 30:583–594
505
Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
Does Caregiver Burden Mediate the Effects of Behavioral Disturbances 15. Aneshensel CS, Pearlin LI, Mullan JT, et al: Profiles in Caregiving: The Unexpected Career. San Diego, Academic Press, 1995 16. Kraemer HC, Wilson GT, Fairburn CG, et al: Mediators and moderators of treatment effects in randomized clinical trials. Arch Gen Psychiatry 2002; 59:877–883 17. Brodaty H, Mittelman M, Gibson L, et al: The effects of counseling spouse caregivers of people with Alzheimer disease taking Donepezil and of country of residence on rates of admission to nursing homes and mortality. Am J Geriatr Psychiatry 2009; 17:734–743 18. Mittelman MS, Brodaty H, Wallen AS, et al: A three-country randomized controlled trial of a psychosocial intervention for caregivers combined with pharmacological treatment for patients with Alzheimer disease: Effects on caregiver depression. Am J Geriatr Psychiatry 2008; 16:893–904 19. Newcomer R, Yordi C, DuNah R, et al: Effects of the Medicare Alzheimer’s Disease Demonstration on caregiver burden and depression. Health Serv Res 1999; 34:669–689 20. Miller R, Newcomer R, Fox P: Effects of the Medicare Alzheimer’s Disease Demonstration evaluation on nursing home entry. Health Serv Res 1999; 34:691–714 21. Zarit SH, Orr N, Zarit J: Understanding the stress of caregivers: planning an intervention, in Hidden Victims of Alzheimer’s Disease: Families Under Stress. Edited by Zarit SH, Orr N, Zarit J. New York, NYU Press, 1985, pp 69–86 22. Fischer J, Corcoran K: Measures for Clinical Practice and Research: A Sourcebook—Couples, Families, and Children. New York, Oxford University Press, 2007 23. Zarit SH, Reever KE, Bach-Peterson J: Relatives of the impaired elderly: correlates of feelings of burden. Gerontologist 1980; 20:649–655 24. Pinquart M, S¨ orensen S: Associations of caregiver stressors and uplifts with subjective well-being and depressive mood: a metaanalytic comparison. Aging Ment Health 2004; 8:438–449 25. Folstein MF, Folstein SE, McHugh PR: Mini-Mental State: a practical method for grading the cognitive state of patients for the clinician. J Psychiatr Res 1975; 12:189–198
506
26. Katz S, Ford AB, Moskowitz RW, et al: Studies of illness in the aged. The index of ADL: a standardized measure of biological and psychosocial function. JAMA 1963; 185:914–919 27. Lawton MP, Brody EM: Assessment of older people: selfmaintaining and instrumental activities of daily living. Gerontologist 1969; 9:179–186 28. Baron RM, Kenny DA: The moderator-mediator variable distinction in social psychological research: Conceptual, strategic, and statistical considerations. J Pers Soc Psychol 1986; 51:1173–1182 29. Shrout PE, Bolger N: Mediation in experimental and nonexperimental studies: new procedures and recommendations. Psychol Methods 2002; 7:422–445 30. Kane RA: Long-term care and a good quality of life: bringing them closer together. Gerontologist 2001; 41:293–304 31. Teri L, Truax P, Logsdon R, et al: Assessment of behavioral problems in dementia: the Revised Memory and Behavior Problems Checklist. Psychol Aging 1992; 7:622–631 32. Ahmed A, Ali M, Lefante CM, et al: Geriatric heart failure, depression, and nursing home admission: an observational study using propensity score analysis. Am J Geriatr Psychiatry 2006; 14: 867–875 33. Andrews AO, Bartels SJ, Xie H, et al: Increased risk of nursing home admission among middle aged and older adults with schizophrenia. Am J Geriatr Psychiatry 2009; 17:697–705 34. Gaugler JE, Mittelman MS, Hepburn K, et al: Predictors of change in caregiver burden and depressive symptoms following nursing home admission. Psychol Aging 2009; 24:385–396 35. Logsdon RG, McCurry SM, Teri L: Evidence-based psychological treatments for disruptive behaviors in individuals with dementia. Psychol Aging 2007; 22:28–36 36. Cohen-Mansfield J: Nonpharmacologic interventions for inappropriate behaviors in dementia: a review, summary, and critique. Am J Geriatr Psychiatry 2001; 9:361–381 37. Callahan CM, Boustani MA, Unverzagt FW, et al: Effectiveness of collaborative care for older adults with Alzheimer disease in primary care: a randomized controlled trial. JAMA 2006; 295: 2148–2157
Am J Geriatr Psychiatry 19:6, June 2011
Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.