Depressive symptoms and functional impairment in the medically Ill

Depressive Symptoms and Functional Impairment in the Medically Ill Gary Rodin, M.D., Associate Professor, Consultation-Liaison

University of Toronto, Deputy Psychiatrist Service, Toronto General Hospital

in

Chief and Coordinator

of Psychiatric

Karen Voshart, B. SC., Research

Associate,

Toronto

General

Hospital

Abstract: Depressive sympfoms of at least moderate severity were reported by more than 25% of a consecutive sample of end-stage renal disease (ESRD) patients awaiting cadaveric transplantation. Subjects with depressive symptoms in the clinically significant range were more often unemployed and were more functionally disabled than subjects with depressive symptoms of lesser severity. Depressive symptoms and functional disability were significantly correlated at lower but not higher levels of depression. Although depressed medical patients fend to be more impaired than fhose who are not depressed, the occurrence of depressive symptoms of clinical severity may depend upon the interaction among multiple additional factors. Clinically significant depression is not inevitable with severe medical disabilities and its occurrence should draw attention to specific individual vulnerabilifies.

End-stage renal disease (ESRD) is a serious medical condition that is fatal unless treated with dialysis or transplantation. In the absence of a functioning renal transplant, survival with this condition requires maintenance dialysis, dietary regulation, medication, and other measures to maintain physiologic homeostasis. Significant depressive symptoms have been reported in more than 50% of ESRD patients [l] and depression may be the most common reason for a psychiatric referral in this population [2]. However, the clinical significance of depressive symptoms in this population has been a matter of some dispute. It has been argued that clinical depression is no more common in ESRD patients than in the general population [3] and General Hospital Psychiatry 9, 251-258, 1987 0 1987 Elsevier Science Publishing Co., Inc. 52 Vanderbilt Ave., New York, NY 10017

Smith et al. suggested that major depression can be diagnosed in only 5% of dialysis patients [4]. By contrast, Lowry [5] found the syndrome of major depression in 22% of dialysis patients. There may also be covert manifestations of depression in the medically ill [6]. It seems likely that the apparently high suicide rate in dialysis patients [7] and the decision of some patients to discontinue dialysis treatment altogether [S] are related, in part, to a lowering of mood. Discrepancies in the reported prevalence of depression in ESRD patients may arise for a variety of reasons [9]. These include differences in the demographic and other characteristics of the samples studied, differing methods of assessment and diagnostic criteria, and differing points in time at which the assessments are carried out. Also, changes in treatment may significantly affect mood. For example, ESRD patients on dialysis report significantly fewer depressive symptoms 6 months after receiving a transplant that functions successfully [lo]. Also, depressive symptoms may diminish over time in dialysis patients due to correction of metabolic imbalances and/or improved adaptation to the illness [l]. However, the factor most consistently associated with depression in the medically ill is the severity of the medical illness [6]. In this regard, Bukberg et al. [ll] noted that criteria for major depression were present in 77% of cancer patients with severe physical disability compared to only 23% of those with little disability.

251 0163.8343/87/$3.50

G. Rodin and K. Voshart

Less severe depressive symptoms may be even more closely related to the medical condition. Akiskal [12] suggests that the dysphoria associated with a chronic medical condition typically follows the course of the medical disorder and may not represent a primary affective process unless there is a family history of affective disorder and/or the onset is associated with a major depressive episode of the melancholic form. It may be that dysphoria is a common or even universal response to serious medical illness, but that the occurrence of major depression depends upon individual vulnerabilities. As part of a study of psychosocial outcome in dialysis patients with end-stage renal disease awaiting cadaveric transplantation, we have evaluated depressive symptoms and illness-related functional impairment. We postulated that depressive symptoms would be common in these patients with ESRD and that the severity of the depressive symptoms would correlate with the severity of functional disability.

Methods The study sample was drawn from a pool of ESRD patients on dialysis and on the waiting list for a cadaveric transplant at one of two large teaching hospitals in Toronto, Canada, between January 1982 and December 1983. Of the 126 patients asked to participate, 115 (91.3%) were considered suitable and gave informed consent. Five patients (4%) refused and six patients (5%) had insufficient command of English to participate. The duration of dialysis treatment in the 115 participating subjects ranged from 3 weeks to 11 years (X=65.5 weeks, SD=66.9). At the time of the assessment, 63 subjects (54.8%) were on home dialysis and 52 subjects (45.2%) were undergoing dialysis in hospital. Of the 63 home dialysis patients, 3 were being treated with intermittent peritoneal dialysis (IPD) and 60 with continuous ambulatory peritoneal dialysis (CAPD). Of the 52 hospital dialysis patients, 45 were treated with hemodialysis and 7 with IPD. Two trained interviewers, including one of the authors (K.V.), carried out the assessments at the time of clinic visits for home dialysis patients and during the dialysis treatment for hospital dialysis patients. In 23 cases, assessments were carried out during an inpatient hospital admission. The assessment measures consisted of a semistructured interview and questionnaires, including the Beck Depression Inventory and the 252

Sickness Impact Profile. These measures and their application in the present study are described briefly below. Beck Depression Inventory (BDI). This is a selfreport inventory of the cognitive-affective and somatic symptoms of depression [13]. This measure was selected because it includes severity and frequency of symptoms, and because it has been used widely in studies of depression in the medically ill. A variety of cutoff points on the BDI have been used by others to identify significant depressive symptoms in medical populations. We have found that a cutoff score of 17 or more provides optimal sensitivity and specificity for the clinical diagnosis of major depression [14]. Gallagher et al. [15] demonstrated a concordance rate of approximately 91% between BDI scores of 17 or more and RDC diagnoses of major depression derived from the SADS. Neilson and Williams [16] also found 17 to be the optimal BDI cutoff score for moderate depression with a sensitivity of 0.66 and a specificity of 0.84 for at least moderate levels of depression diagnosed by clinical interviews. Based on these concordance studies, we have used a cutoff score of 17 or more on the BDI, in the present study, to identify ESRD patients who are significantly depressed. Sickness Impact Profile (SIP). This is a behaviorally based measure of illness-related impairment with demonstrated reliability and validity as a health status measure in medically ill populations [17-191. This instrument was chosen because it provides a multidimensional assessment of illnessrelated functional impairment likely to occur with serious medical conditions such as ESRD. The SIP consists of 136 statements referring to healthrelated activity on which subjects are asked to rate themselves in terms of the preceding 6 months. In scoring this test, the 136 items are grouped into 12 categories. Three of these categories (ambulation, mobility, body care and movement) are grouped to provide a physical dimension score (SIP-phy) and four of the categories (social interaction, communication, emotional behavior, and alertness behavior) are grouped to provide a psychosocial dimension score (SIP-psy). The remaining five categories (eating, work, sleep and rest, household management, recreation, and pastimes) are scored separately. The total score (SIP total) is a weighted average of all 136 items. The SIP scores reflect the degree of impairment such that higher scores reflect worse functioning. It has been suggested that SIP-total scores above 20 are compatible with se-

Depression

Table 1. Demographic

Demographic

Variables

Variables

n

Percent of Sample

63 52

(55%) (45%)

79 18

(69%) (16%)

18

(16%)

106 3 5

(93%)

40 55 20

(35%) (48%) (17%)

46 28 22 17

(41%) (25%) (19%) (15%)

Sex Male Female Marital status Married or common-law Widowed, divorced, separated Single Living arrangement With spouse or family With roommate Alone Vocational status Employed Unemployed due to illness Housewife, student, retired Education Some public school

Completed high school Some postsecondary Completed postsecondary

(3%) (4%)

vere illness-related impairment, 15-20 with moderately severe impairment, lo-15 with moderate impairment, less than 10 with mild impairment, and less than 6 with no impairment (Gilson, personal communication). Analysis of Data. Multiple regression, t test, chi-squares, correlations, and descriptive statistics were obtained using the SPSS-PC statistical package.

Results Demographic characteristics of the subjects are listed in Table 1. The sample consists of 63 males (54.8%) and 52 females 45.2%) ranging in age from 17 to 67 years (X=44.6 years, SD= 12.2). Seventynine (68.7%) were either married or living common-law while only 4% lived alone. Twenty subjects (17.4%) suffered from insulin-dependent diabetes mellitus (IDDM). The BDI was completed in 113 of 115 subjects. Two subjects could not understand or did not complete the measure. The distribution of BDI scores is shown in Figure 1. The scores ranged from 0 to 40 and the mean was 12.8 (SD=9.7). Twenty-nine

and Functional

Impairment

subjects (25.7%) scored 17 or more on the BDI, of whom seven (6.2%) scored more than 30. Eightyfour subjects (74.3%) scored below 17. The distribution of SIP scores in the sample is illustrated in Figure 2. Illness-related functional impairment in the total sample, as reflected in the SIP-total score, ranged from 0.4 to 49.8. The mean SIP-total score was 16.5 (SD = 10.2), which is in the range of moderately severe impairment. Thirtyeight subjects (33%) reported moderate to moderately severe impairment (i.e., SIP-total 10-20) and 41 subjects (35.6%) reported severe impairment (i.e., SIP-totalB20). Only 36 subjects (31.3%) reported mild or no functional impairment (i.e., SIPtotal
G. Rodin and K. Voshart

10 9 0 0x7 &

I3

1111 -

7

$5 2 LL

4 3 2 1

1 012345

not depressed

9 10 11 12 13 14 15 mildly depressed

16

17

16

19 20

21

I I I I r-l l-l 22

23

24

25

26

moderately depressed

Beck Depression Inventory (n = 113)

27

26

29

30

31

32

33

34

35

36

37

36

39

40

severely depressed

Scores

Figure 1. Distribution of BDI Scores in patients with end-stage renal disease. of dialysis treatment was twice as long in the depressed group, neither parametric nor nonparametric tests demonstrated that this difference was significant (Table 2). SIP scores in the total sample and in the depressed and nondepressed groups are shown in Table 3. In the depressed group, the mean SIPtotal score was in the range of severe impairment whereas in the nondepressed group the mean score was in the range of moderate impairment. These differences between the mean scores on the SIPtotal, SIP-phy, and SIP-psy between the depressed nondepressed groups and are statistically significant. Multiple regression models were evaluated to determine whether additional variables would be useful to predict BDI scores. Those variables that

no lmpalrment

mold

moderate

moderately severe

distinguished the depressed group from the nondepressed group were considered (SIP-tot, SIPpsy, SIP-phy, and employment status). Since SIPtotal is highly correlated with both SIP-psy (Pearson r=0.83, p
severe

impairment on the Sickness Impact Profile (n = 115)

Figure 2. Distribution of SIP scores in patients with end-stage renal disease. 254

Depression and Functional Impairment

Table 2. Comparison

of Depressed

and Nondepressed

Subjects

Depressed (BDIz17) (n = 30)

Test for Differences Between Groups

Nondepressed (BDI<17) (n = 83)

Age

X = 41.8 years SD = 11.5

X = 45.2 years SD = 12.2

t = 1.43 p = 0.16

Duration of dialysis (weeks)

X = 103.1 weeks SD = 145.1

X = 52.3 weeks SD = 57.9

t = 1.87 p = 0.1

IDDM Present Absent Marital status Married/Common Law Widow, divorced, separated Single Work status Unemployed due to illness Working, retired, housewife,

n=5

n = 13

n = 25

n = 70

?I = 21 n=5

n = 57

n = 20

Modality CAPD IPD Hospital hemo Location of dialysis Home Hospital

xz = 0.25 p = 0.25

n = 12 n = 14

n=4

student

x2 = 0 p = 0.09

?I = 10

n = 33 n = 50

x2 = 6.1 p < 0.05

n = 12

n = 47

n=5 n = 13

n=5

x2 = 2.8 p = 0.2

n = 13

n = 48 n = 35

n = 31

II = 17

xz = 0.86 p = 0.32

” Mann-Whitney U Test was not significant p = 0.1277.

The multiple regression results indicated that only SIP-total was a significant variable. Stepwise, backward, and forward regression did not permit entry of any variable other than SIP total. Since only one variable entered into the regression equation was significant, univariate statistics were con-

sidered for examining the relationship between depressive symptoms and physical impairment. The relationships between depressive symptoms and functional impairment were evaluated separately for the depressed and nondepressed groups using Pearson correlations. Depression and

Figure 3. Relationship between tional impairment and depression.

Table 3. SIP and BDI Scores in Total Sample and in Depressed and Nondepressed Groups

illness-related

func-

Test Measure

Total Sample (n = 115) X + SD

SIP-total

16.5 2 10.2

SIP-phy

11.7 2 11.2

SIP-psy

14.6 + 11.4

Nondepressed Group (BDI < 17) (n = 83) X * SD 13.0 * 9.0” 9.9 ? 10.4h 11.4 ? 9.9

Depressed Group (BDI 2 17) (n = 30) X * SD 23.8 + 9.5 16.2 2 12.3 23.3 2 10.9

a The depressed and nondepressed different p < 0.0001.

groups are significantly

’ The depressed and nondepressed different p < 0.01.

groups are significantly

255

G. Rodin

and K. Voshart

Table 4. Correlations Between SIP and BDI (Pearson Correlation Coefficients) Total Sample n = 113

Test Measure SIP-total SIP-phy SIP-psy

Nondepressed BDI < 17 n = 83

Depressed BDI > 17 n = 30

r = 0.59 p < 0.001

r = 0.63 p < 0.001

p = 0.277

r = 0.35 p < 0.001

r = 0.44 p < 0.001

p = 0.43

r = 0.10 r = 0.03

r = 0.62

r = 0.59

r = 0.29

p < 0.001

p < 0.001

p = 0.06

illness-related impairment were significantly correlated in the nondepressed group only (Table 4). There was no apparent relationship between BDI scores and SIP scores in the depressed group. Specifically, in the nondepressed group a significant correlation was found between BDI scores and the SIP-total (r = 0.63, p
Discussion We have confirmed in a study of dialysis patients with end-stage renal disease that depressive symptoms and illness-related disability are common in this population. More than 25% of the subjects studied reported significant depressive symptoms and approximately 70% reported at least moderate functional disability. Overall, functional disability and unemployment were more common in subjects who were depressed (based on BDI scores of 17 or more) than in the rest of the sample. Depression and illness-related functional disability were significantly correlated at lower levels of depression (BDI<17). However, there was no significant correlation between these variables in subjects with depressive symptoms in the clinically significant range (BDI scores ~17). The correlation of depressive symptoms with illness-related disability at lower but not higher levels of depression emphasize differences that may exist between clinical and nonclinical depression in the medically ill. Less severe symptoms of depression in the nonclinical range may reflect a ubiquitous, perhaps nonpathologic, response to physical illness. Also, there may be more overlap between 256

milder symptoms of depression and the physical effects of illness. Conclusions about depression in the medically ill that do not take into account differences between milder and more severe degrees of depression may be misleading. It is likely that the occurrence of clinical depression in the medically ill, as in other populations, depends upon complex interrelationships between multiple factors [20-231. These include personality, coping mechanisms, the presence or absence of meaningful social supports, and the genetic or biologic predesposition to depression. Also, the degree of psychologic stress associated with an illness may be related more to its meaning and symbolic significance for particular individuals than to the degree of disability produced by the illness. Thus, it may not be surprising that although depressive symptoms may be reported by more than 50% of dialysis patients [1], the syndrome of major depression is found in only 5% [4] to 22% [5]. Heterogeneity of samples has been a major difficulty in comparing many studies of depression in the medically ill. With regard to the methodology of the present study, it could be argued that the circumstance of being on a waiting list for a transplant is a time of increased worry and/or optimism. However, this situation is not uncommon with dialysis patients and the frequency of depressive symptoms in our sample is similar to that reported in other medical inpatient samples [6]. It might also be argued that the responses of patients interviewed during hospitalization or hemodialysis treatment were influenced by their psychologic state at that time. However, the questions on the SIP and the BDI are not specific to the time of interview and the scores of subjects who were hospitalized at the time of the assessment did not differ from other subjects in terms of depressive symptoms or functional disability. It should also be noted that self-report measures such as the BDI have some limitations in terms of reliability and validity. Although elevated scores on such measures do correlate with clinical diagnoses of major depression [14,15], some patients who are severely depressed are unable or unwilling to report symptoms of depression [23]. Furthermore, depressive symptoms may occur in a variety of pathologic and nonpathologic states [24]. There are several implications from our data in terms of the psychosocial impact of physical illness. First, it is clear that depressive symptoms and functional disability are common in dialysis patients. This is not surprising in view of the considerable

Depression and Functional Impairment

burden for such patients in terms of the requirements of dialysis, the restriction on diet, fluid intake, and physical activity, and the frequently associated physical symptoms and medical complications. The present findings also suggest that although depressed patients have more illnessrelated disability than nondepressed patients, the severity of depressive symptoms in the clinically significant range is not necessarily proportional to the degree of illness-related disability. It may be that the occurrence of clinical depression depends upon multiple factors and individual vulnerabilities in addition to the severity of illness-related disability. By contrast, nonclinical depression may be a realistic nonpathologic response to illness that is more linearly related to the degree of associated disability. Also, the symptoms of physical illness may be more likely to produce false positive scores for depression in the lower range of depressive symptoms. The failure to distinguish depressive symptoms in the clinically significant range from milder symptoms of depression may account for some of the discrepancies in the literature regarding factors associated with depression in the medically ill. More understanding is required regarding those factors that protect many individuals from significant depression in the face of marked disability and stress such as that associated with ESRD and dialysis. In this regard, it is striking that almost 75% of the total sample did not report depressive symptoms of clinical severity. Clinical depression as a specific complication of physical illness is most likely to occur in individuals who are susceptible. Finally, the variable relationship between depression and illness-related disability in the present study emphasizes that a comprehensive assessment of quality of life in the medically ill should include both behavioral and affective measures. In conclusion, although depressive symptoms are common in the medically ill, distinctions between clinical and nonclinical depression may be important. Although the burden of physical illness may result in mild depressive symptoms in the majority of medical patients, it may be that only susceptible individuals are at risk for major depression. The severity of physical illness and its associated disability may not always be an overriding variable in such cases. Some individuals may be relatively protected from clinical depression regardless of their level of physical disability. Finally, caution should be exercised regarding generalizations about depression in the medically ill that do

not take into account differences and nonclinical depression.

between

clinical

The authors wish to acknowledge the cooperation of the Departments of Nephrology at the Toronto General Hospital and Toronto Western Hospital. This study was supported Ontario Mental Health Foundation.

by grant #935-85187

from the

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of psychological impairment. J Nerv Ment Dis 166:307-316, 1978 23. Prusoff BA, Klerman GL, Paykel ES: Concordance between clinical assessments and patients self-report in depression. Arch Gen Psychiatry 26:546-552,1972 24. Gotlib IH: Depression and general psychopathology in university students. J Abnorm Psycho1 93:19-30, 1984 Direct reprint requests to: Dr. G. Rodin Department of Psychiatry Toronto General Hospital 101 College Street Toronto, Ontario M5G lL7