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Gender patterns in cost effectiveness of quality improvement for depression: Results of a randomized, controlled trial
Journal of Affective Disorders 87 (2005) 319 – 325 www.elsevier.com/locate/jad
Brief report
Gender patterns in cost effectiveness of quality improvement for depression: Results of a randomized, controlled trial Michael Schoenbaum a,*, Cathy Sherbourne b, Kenneth Wells b,c a
RAND Corporation, 1200 South Hayes Street, Arlington, VA 22202-5050, USA RAND, 1776 Main Street, P.O. Box 2138, Santa Monica, CA 90407-2138, USA c UCLA-NPI, 10929 Wilshire Boulevard, Suite 300, Los Angeles, CA 90024, USA b
Received 5 May 2004; accepted 29 March 2005 Available online 11 July 2005
Abstract Background: Little is known about gender differences in the costs and outcomes of primary care quality improvement strategies for depression. Methods: Intent-to-treat analysis of data from a group-level controlled trial, in which matched primary care clinics in the US were randomized to usual care or to one of two interventions designed to increase the rate of effective depression treatment. One intervention facilitated medication management (bQI-MedsQ) and the other psychotherapy (bQI-TherapyQ), but patients and clinicians could choose the type of treatment, or none. The study involved 46 clinics in 6 non-academic, managed care organizations; 181 primary care providers; and 375 male and 981 female patients with current depression. Outcomes are health care costs, quality-adjusted life years (QALY), depression burden, employment, and costs/QALY, over 24 months of follow-up. Results: Relative to usual care, QI-Therapy significantly reduced depression burden and increased employment, for men and women; but QI-Meds significantly reduced depression burden only among women. Average health care costs increased $429 in QI-Meds and $983 in QI-Therapy among men; corresponding cost increases were $424 and $275 for women. The estimated cost per QALY for men ranged between $16,600 and $42,600 under QI-Therapy. For women, estimated costs per QALY were $23,600 or below for QI-Meds and $12,500 or below under QI-Therapy. Limitations: This study may be underpowered for some relevant outcomes, particularly costs. The study population is limited to patients who sought health care in primary care settings.
* Corresponding author. Tel.: +1 703 413 1100x5426; fax: +1 703 413 8111. E-mail address: [email protected] (M. Schoenbaum). 0165-0327/$ - see front matter D 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.jad.2005.03.018
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Conclusions: Both men and women can benefit substantially from quality improvement interventions for depression in primary care. Results are particularly favorable for the QI-Therapy intervention. D 2005 Elsevier B.V. All rights reserved. Keywords: Gender differences; Cost effectiveness; Quality improvement for depression
1. Introduction Numerous studies have shown that strategies to improve quality of care for depression in primary care can improve clinical and functional outcomes and are also relatively cost effective (Katon et al., 1995; Schoenbaum et al., 2001; Schulberg et al., 1996; Sherbourne et al., 2001; Simon et al., 2001; Wells et al., 2000). For instance, in our previous research, the Partners in Care (PIC) project, a randomized controlled trial of two quality improvement (QI) interventions for depression in managed primary care settings, both interventions improved clinical outcomes; costs were relatively modest, relative to usual care (UC); and the cost effectiveness of both interventions was comparable to other accepted medical interventions (Schoenbaum et al., 2001). Subsequent analyses, however, indicate that the effects of QI interventions may depend on patient characteristics (Sherbourne et al., 2004). Here, we examine the cost effectiveness of the PIC interventions for men as compared to women. Such an analysis is warranted because depressed men are more likely than women to experience unmet need for appropriate mental health care (Young et al., 2001). This observation, along with evidence that QI strategies for depression may be especially effective among patients beginning a new course of treatment (Rost et al., 2001), suggests that clinical benefits from PIC might be particularly strong for men. Although Pyne et al. (2003) found that a primary care QI intervention for depression improved outcomes and was relatively cost effective compared to UC for women but not for men, that study was described as bexploratoryQ by its authors due to limited sample size. The PIC study, which is based on a larger sample, offers an opportunity to obtain more reliable estimates of outcomes and costs for male and female patients separately. For the reasons noted above, we hypothesized that the effectiveness of the QI programs might be particularly positive for men relative to usual care; however, we had no specific hypotheses about the
effects on costs or cost effectiveness of the PIC interventions by gender.
2. Methods Partners in Care (PIC) is a group-level, randomized controlled trial of practice-initiated QI programs for depression (Wells, 1999). 2.1. Organizations, clinics, and providers Six managed care organizations participated. The sites included a staff model HMO, several group model HMOs, an independent physician network, and a public delivery system. All primary care practices with at least two clinicians were eligible to participate; 46 out of 48 did so. Within organizations, practices were matched into blocks of three clusters, based on factors expected to affect outcomes. Within blocks, practices were randomized to usual care or one of two QI programs (QI-Meds or QI-Therapy). Primary care clinicians were recruited before learning their clinic’s randomized assignment; 181 out of 183 (99%) agreed to participate. 2.2. Patients Study staff screened 27,332 consecutive patients between June 1996 and March 1997. Patients were eligible for the study if they intended to use the clinic as a source of care for the next year, were over age 17, did not have an acute medical emergency, spoke English or Spanish, and had either insurance or a publicpay arrangement that covered the intervention care. Eligible patients were screened for depression using the bstemQ items for major depressive and dysthymic disorder from the 12-month Composite International Diagnostic Interview (WHO, 1997), and items assessing depressed symptoms in the past month.
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Of those completing the screener, 3918 were potentially eligible for the study. Of those, 241 were found ineligible. Of those who read the informed consent, 1356 (79%) enrolled: 443 in UC, 424 in QI-Meds, and 489 in QI-Therapy (375 male and 981 female patients). Self-administered mail surveys were obtained at baseline and every 6 months for 2 years. Response rates were 88% for the baseline survey, and 83% for 6- and 12-month surveys. Nonresponse weights are used to adjust for differential enrollment (McCaffrey et al., 2000).
2.4. Cost measures
2.3. Interventions
2.4.2. Health care cost Costs were assigned to patient-reported counts of emergency department visits, medical and mental health visits, and psychotropic medications used, for each follow-up. Patient report was selected due to limitations in the available claims and encounter data. In addition, the number of outpatient visits was higher for patient surveys than claims data over the first 6 months, probably due to out-of-practice use or incomplete claims data. Costs in 1998 dollars were assigned to each component of patient-reported health care use using a national database of 1.8 million privately insured individuals (provided by Ingenix, a benefits consulting firm in New Haven, CT). The Ingenix data included information on provider reimbursements, which were used as a proxy for health care costs. These costs include facility charges, professional fees, and ancillary services associated with the visits. Visit counts reported by PIC patients were multiplied by the mean costs of these services. For psychotropic medications, medication names, dosages, and months of use were matched in the Ingenix data to obtain average costs for that combination. Indirect costs of treatment include patient time costs for obtaining health care (Gold et al., 1996), which consist of time for outpatient medical and mental health visits; emergency department visits, travel and waiting times, and time to fill prescriptions. Patients’ time was priced using reported hourly wage at baseline and sex-specific mean wage for those not working.
Intervention design and implementation are described in Wells (Wells, 1999). All intervention materials are available from RAND (www.rand.org/ organization/health/pic.products/order.html). Participating practices were paid up to half of the estimated participation costs ($35–70 K). The interventions provided practices with training and resources to initiate and monitor QI programs according to local practice goals and resources. UC clinics received depression practice guidelines by mail. For both QI-Meds and QI-Therapy, local practice teams were trained in a 2-day workshop. Designated practice nurses were trained as depression specialists, and practices were provided with patient education materials, patient tracking forms, and clinician manuals and pocket reminder cards and were encouraged to distribute them. The materials described guideline-concordant care for depression and presented psychotherapy and antidepressant medication as equally effective. In QI-Meds, trained nurses were available to provide follow-up assessments and support for adherence to care for 6 months (12 months for a randomly selected half of QI-Meds patients). In QI-Therapy, the study provided local psychotherapists with manuals, and it trained them in 8–12 session courses of individual and group Cognitive Behavioral Therapy (CBT) (Munoz et al., 1986; Munoz and Miranda, 1986). For psychotherapy provided by the study-trained therapists, patient copayments were reduced to the amount charged for primary care visits. In each study arm, patients and clinicians retained choice of treatment, and their use of intervention resources was optional. No study resources were available to UC patients.
2.4.1. Intervention cost These included screening, intervention materials, initial nurse specialist assessments, and 20 min of supervision of nurses and therapists per enrolled patient. Costs of intervention activities were based on data from the practices about the average cost of clinic staff. Research-specific costs were excluded. Followup visits to intervention staff were included in patient reports of outpatient visits.
2.5. Outcomes 2.5.1. Quality-adjusted life years A health utility index from the Short-Form, 12Item Health Survey (SF-12) (Ware et al., 1995) was
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developed specifically for the overall study to measure quality-adjusted life years (QALYs) (Lenert et al., 2000). QALY weights were calculated for each 6month follow-up period. This measure is called bQALY-SF.Q 2.5.2. Days of depression burden Following an approach developed by Lave et al. (1998), we developed a measure of depression burden days and assigned utility scores from the literature to estimate QALYs. For each survey, we developed a count of positive scores on the following three measures: probable major depressive disorder, based on a repeat of the baseline screener (Wells et al., 2000); significant depressive symptoms, based on a modified Center for Epidemiologic Studies Depression Scale (Radloff, 1977; Wells et al., 2000); and poor mental health-related quality of life (HRQOL), based on being more than 1 SD below the population mean on the mental health composite of the SF-12. We averaged the count for the beginning and end of each 6-month follow-up period and multiplied by 182 to estimate depression burden days during the period. We summed across periods to get the 24-month total. We then used findings from the literature that a year of depression is associated with losses of 0.2 to 0.4 QALYs to convert the intervention effect on depression burden days into the QALY-DB estimates (Fryback et al., 1993; Revicki et al., 1998; Unu¨tzer et al., 1997). 2.5.3. Employment Employment was measured by averaging employment status at the start and end of each 6-month period and multiplying by 116 (the number of workdays in 6 months). Total 24-month figures were obtained by summing across periods. Days missed from work due to illness for the 4 weeks preceding each follow-up survey were also examined. 2.6. Covariates All multivariate models controlled for age, sex, marital status, education, household wealth, employment status, medical comorbidity, depressive disorder status, the SF-12 aggregate HRQOL measures, presence of comorbid anxiety disorder, and practice randomization block.
2.7. Data analysis We replicated the analyses in Schoenbaum et al. (2001), separately for males and females. To estimate the effects of practice-initiated QI on patients, we conducted patient-level intent-to-treat analyses, controlling for baseline patient differences that could remain after group-level randomization. We examined intervention effects on care costs using two-part models, due to the skewed distribution of costs: the first part is the probability of positive costs, using logistic regression; second is the log of costs given any, using OLS regression (Duan et al., 1983). We used smearing estimate for retransformation, applying separate factors for each intervention group to ensure consistent estimates (Duan, 1983). We did not adjust cost models for clustering by clinic because we know of no standard methods to do so for two-part models. We expect the interventions to increase costs, relative to UC; not accounting for clustering is thus conservative, since it is likely to overstate the statistical significance of cost differences. For the QALY-SF measure, we specified 3-level (repeated measurements nested within patients, and patients nested within clinics) mixed effects linear time-trend regression models, controlling for the baseline utility value in addition to the covariates listed above (except HRQOL). We calculated the area under the QALY time trajectory to derive values over 24 months. For days of depression burden and employment, respectively, we specified 2-level (patients nested within clinics) mixed effects linear regression models, to account for patient clustering at the practice level. For these outcomes, we examined the 24month value directly. We analyzed patients completing at least one follow-up (92% of the enrolled sample; N = 1248 total). The data are weighted for the probability of study enrollment and follow-up response to the characteristics of the eligible sample. We used multiple imputations for missing items at each wave (Little, 1993; Little and Rubin, 1987). For outcomes, we average predictions from five randomly imputed data sets and adjusted standard errors for uncertainty due to imputation (Little and Rubin, 1987). We illustrate average intervention effects relative to usual care, adjusted for patient characteristics using standardized predictions generated from each regression model.
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Because many tests are in the direction hypothesized, a formal Bonferroni correction for multiple statistical comparisons is too conservative, so we report actual p-values and interpret results with multiple comparisons in mind (Miller, 1981).
3. Results Descriptive analyses of the study sample revealed no significant differences in age, educational attainment, or severity of depression between men in the intervention arms and controls at baseline. Among women, there were no significant differences in age, but patients in the intervention group were somewhat better educated than the controls. They were also more likely to have current major depression or dysthymia (vs. subthreshold symptoms; p b 0.01 for QIMeds, relative to UC). Among both men and women, patterns of depression treatment prior to enrollment were generally balanced by intervention status; however, initial treatment rates were around 1/3 higher for women than for men. Average total per patient costs for men under UC were estimated at $3148 per patient, increasing by $429 for QI-Meds (NS) and $983 for QI-Therapy ( p b 0.10) participants. Increases under QI-Meds were due to higher costs for outpatient mental health visits and psychotropic medications (both NS). Increases under QI-Therapy were due to significantly higher costs for outpatient mental health visits (more than 80% increase over usual care, p b 0.10) and ER visits. Average per patient total costs for UC female patients was estimated at $4139 per patient, increasing by $425 for QI-Meds and $275 for QI-Therapy participants (both NS). Increases under QI-Meds were primarily due to higher costs for psychotropic medications (approximately 60% increase over usual care, p b 0.05). Compared with men, increases in outpatient mental health visits for women under QI-Therapy were substantially smaller in absolute terms and as a fraction of UC; the point estimate for ER costs was actually negative for women. For the QALY-SF measure among men, the incremental increase due to QI-Therapy was 0.023 (NS). Combining this point estimate with our point estimates of the incremental intervention costs yields an estimated cost per QALY of $42,554 for QI-Therapy. For QI-
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Meds, the incremental effect on QALY-SF was estimated to be negative ( 0.011, NS); based on this point estimate, QI-Meds is not effective and thus by definition not cost effective for men. For women, the incremental increase due to QI-Meds was 0.018 ( p = 0.06) and for QI-Therapy was 0.022 ( p = 0.019); this yields an incremental intervention cost per QALY of $23,611 for QI-Meds and $12,500 for QI-Therapy. The QALY-DB measure is based on estimates that depression reduces the value of a life year by 0.2 to 0.4 QALYs (Fryback et al., 1993; Lave et al., 1998; Unu¨tzer et al., 1997). For men, compared with UC, the point estimate suggests that QI-Meds increased depression burden (NS) and is thus not cost effective by this measure either; however, QI-Therapy reduced depression burden days by 54 over 24 months ( p = 0.11), corresponding to 0.030 to 0.059 QALYs and costs per QALY of $16,611 to $33,222. For women, compared with UC, QI-Meds reduced the number of depression burden days by 50 ( p = 0.038; corresponding to 0.027 to 0.055 QALYs and costs per QALY of $7756 to $15,512) and QI-Therapy by 51 ( p = 0.014; corresponding to 0.028 to 0.056 QALYs and costs per QALY of $4920 to $9841). Among men, QI-Meds increased days of employment by 6 (NS) and QI-Therapy by 37 days ( p = 0.022), over 2 years. Among women, QI-Meds increased days of employment by 26 days ( p = 0.0245), while QITherapy was estimated to increase employment by 14 days (NS).
4. Discussion This paper evaluated cost effectiveness of improving care for depression, examining male and female patients separately. Among men, QI-Therapy led to substantial clinical improvement; however, it also increased health care costs over 24 months by around one-third, relative to UC, yielding a relative cost effectiveness towards the upper range of accepted medical interventions (Gold et al., 1996; Tengs et al., 1995). Our results suggest that QI-Meds is not clinically effective, and therefore not cost effective, for depressed men. Among women, QI-Meds and QI-Therapy had comparable effects on depression burden and quality of life. The relative cost effectiveness for both interventions was well within the
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range of other accepted medical interventions, particularly for QI-Therapy due to its relatively small effect on costs. These results are consistent with our findings for the overall study sample, except for the more disappointing effects of QI-Meds among depressed men (Schoenbaum et al., 2001; Wells et al., 2000). However, most QI studies have not had sufficient sample sizes to examine differential effectiveness among demographic groups, and particularly, to estimate intervention effectiveness for depressed men. Therefore, we do not know if our results of differential effectiveness of QI-Meds by gender are unique to PIC. As QIMeds, given its focus on enhancing medication management while permitting access to psychotherapy, seems more likely than QI-Therapy to be considered for use in primary care, it is important to note the positive results of QI-Therapy for both men and women. Employment is an important outcome in its own right for patients and payers, and it may not be fully captured in standard measures of QALYs (Gold et al., 1996). Intervention effects on employment were particularly large for men under QI-Therapy, with the increase relative to UC corresponding to more than 7 work weeks over 2 years; for women under QIMeds, the increase corresponded to more than 5 work weeks. The point estimate for employment effects under QI-Therapy for women was still qualitatively important – 14 days, or around 3 work weeks – but statistical precision was lower. The relationships between improved depression care, clinical improvement, and labor supply warrant additional study. There are several limitations to this study. First, because our cost estimates lack precision, the study may not have the power to detect subgroup differences in costs or outcomes between men and women. Second, outcomes are self-reported and may be subject to recall bias; any such bias, however, should be equivalent across intervention groups and should not bias estimates of intervention effects. Third, we studied only six practice networks; although they were chosen to be diverse, they may not be representative of all practice networks. Fourth, our study population includes only patients who sought health care (although not necessarily depression care) from a primary care provider; this covers approximately 80% of depressed patients (Young et al., 2001). Finally, while
each intervention had several components, the current design does not allow us to identify the effects of individual components. Thus, we do not know whether the positive outcomes of QI-Therapy for men are attributable to psychotherapeutic treatment generally, the particular form of therapy (i.e., CBT), the quality of provider training, the reduced copayments for psychotherapy from study-trained providers, or other factors. Similarly, we do not understand why QI-Meds was effective for women but not for men, nor why QIMeds yielded larger improvements in women’s labor supply than did QI-Therapy. Additional information on these issues may help guide efforts to further improve the effectiveness and cost effectiveness of depression treatment, for all types of patients.
Acknowledgements This work was funded by the National Institutes of Mental Health (R01MH64658, P50MH54623), the Agency for Healthcare Research and Quality (R01HS08349), and the John D. and Catherine T. MacArthur Foundation (Grant No. 96-42901A-HE).
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M. Schoenbaum et al. / Journal of Affective Disorders 87 (2005) 319–325 Little, R.J.A., Rubin, D.B., 1987. Statistical Analysis with Missing Data. J. Wiley & Sons, New York, NY. McCaffrey, D.F., Duan, N., Morton, S.C., 2000. Propagation of nonresponse weights for censoring in multi-phase screening in complex sample designs. Health Serv. Outcomes Res. Methodol. 1, 213 – 231. Miller, R.G.J., 1981. Simultaneous Statistical Inference, 2nd edition. Springer-Verlag, New York, NY. Munoz, R.F., Miranda, J., 1986. Group Therapy for Cognitive Behavioral Treatment of Depression. San Francisco General Hospital Depression Clinic, San Francisco, CA. Munoz, R.F., Aguilar-Gaxiola, S., Guzman, J., 1986. Manual de terapia de grupo para el tratamiento cognitivo-conductal de depresion. Hospital General de San Francisco Clinica de Depresion, San Francisco, CA. Pyne, J.M., Smith, J., Fortney, J., Zhang, M., Williams, D.K., Rost, K., 2003. Cost effectiveness of a primary care intervention for depressed females. J. Affect. Disord. 74, 23 – 32. Radloff, L.S., 1977. The CES-D scale: a self-report depression scale for research in the general population. Appl. Psychol. Meas. 1, 385 – 401. Revicki, D.A., Simon, G.E., Chan, K., Katon, W., Leiligenstein, J., 1998. Depression, health-related quality of life, and medical cost outcomes of receiving recommended levels of antidepressant treatment. J. Fam. Pract. 47, 446 – 452. Rost, K., Nutting, P., Smith, J., Werner, J., Duan, N., 2001. Improving depression outcomes in community primary care practice: a randomized trial of the quEST intervention. Quality enhancement by strategic team. J. Gen. Intern. Med. 16, 143 – 149. Schoenbaum, M., Unu¨tzer, J., Sherbourne, C.D., Duan, N., Rubenstein, L.V., Miranda, J., Meredith, L.S., Carney, M.F., Wells, K., 2001. The cost-effectiveness of practice-initiated quality improvement for depression: results of a randomized controlled trial. JAMA 286, 1325 – 1330. Schulberg, H.C., Block, M.R., Madonia, M.J., Scott, C.P., Rodriguez, E., Imber, S.D., Perel, J., Lave, J., Houck, P.R., Coulehan, J.L., 1996. Treating major depression in primary care practice: eight-month clinical outcomes. Arch. Gen. Psychiatry 53, 913 – 919.
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Brief report
Gender patterns in cost effectiveness of quality improvement for depression: Results of a randomized, controlled trial Michael Schoenbaum a,*, Cathy Sherbourne b, Kenneth Wells b,c a
RAND Corporation, 1200 South Hayes Street, Arlington, VA 22202-5050, USA RAND, 1776 Main Street, P.O. Box 2138, Santa Monica, CA 90407-2138, USA c UCLA-NPI, 10929 Wilshire Boulevard, Suite 300, Los Angeles, CA 90024, USA b
Received 5 May 2004; accepted 29 March 2005 Available online 11 July 2005
Abstract Background: Little is known about gender differences in the costs and outcomes of primary care quality improvement strategies for depression. Methods: Intent-to-treat analysis of data from a group-level controlled trial, in which matched primary care clinics in the US were randomized to usual care or to one of two interventions designed to increase the rate of effective depression treatment. One intervention facilitated medication management (bQI-MedsQ) and the other psychotherapy (bQI-TherapyQ), but patients and clinicians could choose the type of treatment, or none. The study involved 46 clinics in 6 non-academic, managed care organizations; 181 primary care providers; and 375 male and 981 female patients with current depression. Outcomes are health care costs, quality-adjusted life years (QALY), depression burden, employment, and costs/QALY, over 24 months of follow-up. Results: Relative to usual care, QI-Therapy significantly reduced depression burden and increased employment, for men and women; but QI-Meds significantly reduced depression burden only among women. Average health care costs increased $429 in QI-Meds and $983 in QI-Therapy among men; corresponding cost increases were $424 and $275 for women. The estimated cost per QALY for men ranged between $16,600 and $42,600 under QI-Therapy. For women, estimated costs per QALY were $23,600 or below for QI-Meds and $12,500 or below under QI-Therapy. Limitations: This study may be underpowered for some relevant outcomes, particularly costs. The study population is limited to patients who sought health care in primary care settings.
* Corresponding author. Tel.: +1 703 413 1100x5426; fax: +1 703 413 8111. E-mail address: [email protected] (M. Schoenbaum). 0165-0327/$ - see front matter D 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.jad.2005.03.018
320
M. Schoenbaum et al. / Journal of Affective Disorders 87 (2005) 319–325
Conclusions: Both men and women can benefit substantially from quality improvement interventions for depression in primary care. Results are particularly favorable for the QI-Therapy intervention. D 2005 Elsevier B.V. All rights reserved. Keywords: Gender differences; Cost effectiveness; Quality improvement for depression
1. Introduction Numerous studies have shown that strategies to improve quality of care for depression in primary care can improve clinical and functional outcomes and are also relatively cost effective (Katon et al., 1995; Schoenbaum et al., 2001; Schulberg et al., 1996; Sherbourne et al., 2001; Simon et al., 2001; Wells et al., 2000). For instance, in our previous research, the Partners in Care (PIC) project, a randomized controlled trial of two quality improvement (QI) interventions for depression in managed primary care settings, both interventions improved clinical outcomes; costs were relatively modest, relative to usual care (UC); and the cost effectiveness of both interventions was comparable to other accepted medical interventions (Schoenbaum et al., 2001). Subsequent analyses, however, indicate that the effects of QI interventions may depend on patient characteristics (Sherbourne et al., 2004). Here, we examine the cost effectiveness of the PIC interventions for men as compared to women. Such an analysis is warranted because depressed men are more likely than women to experience unmet need for appropriate mental health care (Young et al., 2001). This observation, along with evidence that QI strategies for depression may be especially effective among patients beginning a new course of treatment (Rost et al., 2001), suggests that clinical benefits from PIC might be particularly strong for men. Although Pyne et al. (2003) found that a primary care QI intervention for depression improved outcomes and was relatively cost effective compared to UC for women but not for men, that study was described as bexploratoryQ by its authors due to limited sample size. The PIC study, which is based on a larger sample, offers an opportunity to obtain more reliable estimates of outcomes and costs for male and female patients separately. For the reasons noted above, we hypothesized that the effectiveness of the QI programs might be particularly positive for men relative to usual care; however, we had no specific hypotheses about the
effects on costs or cost effectiveness of the PIC interventions by gender.
2. Methods Partners in Care (PIC) is a group-level, randomized controlled trial of practice-initiated QI programs for depression (Wells, 1999). 2.1. Organizations, clinics, and providers Six managed care organizations participated. The sites included a staff model HMO, several group model HMOs, an independent physician network, and a public delivery system. All primary care practices with at least two clinicians were eligible to participate; 46 out of 48 did so. Within organizations, practices were matched into blocks of three clusters, based on factors expected to affect outcomes. Within blocks, practices were randomized to usual care or one of two QI programs (QI-Meds or QI-Therapy). Primary care clinicians were recruited before learning their clinic’s randomized assignment; 181 out of 183 (99%) agreed to participate. 2.2. Patients Study staff screened 27,332 consecutive patients between June 1996 and March 1997. Patients were eligible for the study if they intended to use the clinic as a source of care for the next year, were over age 17, did not have an acute medical emergency, spoke English or Spanish, and had either insurance or a publicpay arrangement that covered the intervention care. Eligible patients were screened for depression using the bstemQ items for major depressive and dysthymic disorder from the 12-month Composite International Diagnostic Interview (WHO, 1997), and items assessing depressed symptoms in the past month.
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Of those completing the screener, 3918 were potentially eligible for the study. Of those, 241 were found ineligible. Of those who read the informed consent, 1356 (79%) enrolled: 443 in UC, 424 in QI-Meds, and 489 in QI-Therapy (375 male and 981 female patients). Self-administered mail surveys were obtained at baseline and every 6 months for 2 years. Response rates were 88% for the baseline survey, and 83% for 6- and 12-month surveys. Nonresponse weights are used to adjust for differential enrollment (McCaffrey et al., 2000).
2.4. Cost measures
2.3. Interventions
2.4.2. Health care cost Costs were assigned to patient-reported counts of emergency department visits, medical and mental health visits, and psychotropic medications used, for each follow-up. Patient report was selected due to limitations in the available claims and encounter data. In addition, the number of outpatient visits was higher for patient surveys than claims data over the first 6 months, probably due to out-of-practice use or incomplete claims data. Costs in 1998 dollars were assigned to each component of patient-reported health care use using a national database of 1.8 million privately insured individuals (provided by Ingenix, a benefits consulting firm in New Haven, CT). The Ingenix data included information on provider reimbursements, which were used as a proxy for health care costs. These costs include facility charges, professional fees, and ancillary services associated with the visits. Visit counts reported by PIC patients were multiplied by the mean costs of these services. For psychotropic medications, medication names, dosages, and months of use were matched in the Ingenix data to obtain average costs for that combination. Indirect costs of treatment include patient time costs for obtaining health care (Gold et al., 1996), which consist of time for outpatient medical and mental health visits; emergency department visits, travel and waiting times, and time to fill prescriptions. Patients’ time was priced using reported hourly wage at baseline and sex-specific mean wage for those not working.
Intervention design and implementation are described in Wells (Wells, 1999). All intervention materials are available from RAND (www.rand.org/ organization/health/pic.products/order.html). Participating practices were paid up to half of the estimated participation costs ($35–70 K). The interventions provided practices with training and resources to initiate and monitor QI programs according to local practice goals and resources. UC clinics received depression practice guidelines by mail. For both QI-Meds and QI-Therapy, local practice teams were trained in a 2-day workshop. Designated practice nurses were trained as depression specialists, and practices were provided with patient education materials, patient tracking forms, and clinician manuals and pocket reminder cards and were encouraged to distribute them. The materials described guideline-concordant care for depression and presented psychotherapy and antidepressant medication as equally effective. In QI-Meds, trained nurses were available to provide follow-up assessments and support for adherence to care for 6 months (12 months for a randomly selected half of QI-Meds patients). In QI-Therapy, the study provided local psychotherapists with manuals, and it trained them in 8–12 session courses of individual and group Cognitive Behavioral Therapy (CBT) (Munoz et al., 1986; Munoz and Miranda, 1986). For psychotherapy provided by the study-trained therapists, patient copayments were reduced to the amount charged for primary care visits. In each study arm, patients and clinicians retained choice of treatment, and their use of intervention resources was optional. No study resources were available to UC patients.
2.4.1. Intervention cost These included screening, intervention materials, initial nurse specialist assessments, and 20 min of supervision of nurses and therapists per enrolled patient. Costs of intervention activities were based on data from the practices about the average cost of clinic staff. Research-specific costs were excluded. Followup visits to intervention staff were included in patient reports of outpatient visits.
2.5. Outcomes 2.5.1. Quality-adjusted life years A health utility index from the Short-Form, 12Item Health Survey (SF-12) (Ware et al., 1995) was
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developed specifically for the overall study to measure quality-adjusted life years (QALYs) (Lenert et al., 2000). QALY weights were calculated for each 6month follow-up period. This measure is called bQALY-SF.Q 2.5.2. Days of depression burden Following an approach developed by Lave et al. (1998), we developed a measure of depression burden days and assigned utility scores from the literature to estimate QALYs. For each survey, we developed a count of positive scores on the following three measures: probable major depressive disorder, based on a repeat of the baseline screener (Wells et al., 2000); significant depressive symptoms, based on a modified Center for Epidemiologic Studies Depression Scale (Radloff, 1977; Wells et al., 2000); and poor mental health-related quality of life (HRQOL), based on being more than 1 SD below the population mean on the mental health composite of the SF-12. We averaged the count for the beginning and end of each 6-month follow-up period and multiplied by 182 to estimate depression burden days during the period. We summed across periods to get the 24-month total. We then used findings from the literature that a year of depression is associated with losses of 0.2 to 0.4 QALYs to convert the intervention effect on depression burden days into the QALY-DB estimates (Fryback et al., 1993; Revicki et al., 1998; Unu¨tzer et al., 1997). 2.5.3. Employment Employment was measured by averaging employment status at the start and end of each 6-month period and multiplying by 116 (the number of workdays in 6 months). Total 24-month figures were obtained by summing across periods. Days missed from work due to illness for the 4 weeks preceding each follow-up survey were also examined. 2.6. Covariates All multivariate models controlled for age, sex, marital status, education, household wealth, employment status, medical comorbidity, depressive disorder status, the SF-12 aggregate HRQOL measures, presence of comorbid anxiety disorder, and practice randomization block.
2.7. Data analysis We replicated the analyses in Schoenbaum et al. (2001), separately for males and females. To estimate the effects of practice-initiated QI on patients, we conducted patient-level intent-to-treat analyses, controlling for baseline patient differences that could remain after group-level randomization. We examined intervention effects on care costs using two-part models, due to the skewed distribution of costs: the first part is the probability of positive costs, using logistic regression; second is the log of costs given any, using OLS regression (Duan et al., 1983). We used smearing estimate for retransformation, applying separate factors for each intervention group to ensure consistent estimates (Duan, 1983). We did not adjust cost models for clustering by clinic because we know of no standard methods to do so for two-part models. We expect the interventions to increase costs, relative to UC; not accounting for clustering is thus conservative, since it is likely to overstate the statistical significance of cost differences. For the QALY-SF measure, we specified 3-level (repeated measurements nested within patients, and patients nested within clinics) mixed effects linear time-trend regression models, controlling for the baseline utility value in addition to the covariates listed above (except HRQOL). We calculated the area under the QALY time trajectory to derive values over 24 months. For days of depression burden and employment, respectively, we specified 2-level (patients nested within clinics) mixed effects linear regression models, to account for patient clustering at the practice level. For these outcomes, we examined the 24month value directly. We analyzed patients completing at least one follow-up (92% of the enrolled sample; N = 1248 total). The data are weighted for the probability of study enrollment and follow-up response to the characteristics of the eligible sample. We used multiple imputations for missing items at each wave (Little, 1993; Little and Rubin, 1987). For outcomes, we average predictions from five randomly imputed data sets and adjusted standard errors for uncertainty due to imputation (Little and Rubin, 1987). We illustrate average intervention effects relative to usual care, adjusted for patient characteristics using standardized predictions generated from each regression model.
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Because many tests are in the direction hypothesized, a formal Bonferroni correction for multiple statistical comparisons is too conservative, so we report actual p-values and interpret results with multiple comparisons in mind (Miller, 1981).
3. Results Descriptive analyses of the study sample revealed no significant differences in age, educational attainment, or severity of depression between men in the intervention arms and controls at baseline. Among women, there were no significant differences in age, but patients in the intervention group were somewhat better educated than the controls. They were also more likely to have current major depression or dysthymia (vs. subthreshold symptoms; p b 0.01 for QIMeds, relative to UC). Among both men and women, patterns of depression treatment prior to enrollment were generally balanced by intervention status; however, initial treatment rates were around 1/3 higher for women than for men. Average total per patient costs for men under UC were estimated at $3148 per patient, increasing by $429 for QI-Meds (NS) and $983 for QI-Therapy ( p b 0.10) participants. Increases under QI-Meds were due to higher costs for outpatient mental health visits and psychotropic medications (both NS). Increases under QI-Therapy were due to significantly higher costs for outpatient mental health visits (more than 80% increase over usual care, p b 0.10) and ER visits. Average per patient total costs for UC female patients was estimated at $4139 per patient, increasing by $425 for QI-Meds and $275 for QI-Therapy participants (both NS). Increases under QI-Meds were primarily due to higher costs for psychotropic medications (approximately 60% increase over usual care, p b 0.05). Compared with men, increases in outpatient mental health visits for women under QI-Therapy were substantially smaller in absolute terms and as a fraction of UC; the point estimate for ER costs was actually negative for women. For the QALY-SF measure among men, the incremental increase due to QI-Therapy was 0.023 (NS). Combining this point estimate with our point estimates of the incremental intervention costs yields an estimated cost per QALY of $42,554 for QI-Therapy. For QI-
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Meds, the incremental effect on QALY-SF was estimated to be negative ( 0.011, NS); based on this point estimate, QI-Meds is not effective and thus by definition not cost effective for men. For women, the incremental increase due to QI-Meds was 0.018 ( p = 0.06) and for QI-Therapy was 0.022 ( p = 0.019); this yields an incremental intervention cost per QALY of $23,611 for QI-Meds and $12,500 for QI-Therapy. The QALY-DB measure is based on estimates that depression reduces the value of a life year by 0.2 to 0.4 QALYs (Fryback et al., 1993; Lave et al., 1998; Unu¨tzer et al., 1997). For men, compared with UC, the point estimate suggests that QI-Meds increased depression burden (NS) and is thus not cost effective by this measure either; however, QI-Therapy reduced depression burden days by 54 over 24 months ( p = 0.11), corresponding to 0.030 to 0.059 QALYs and costs per QALY of $16,611 to $33,222. For women, compared with UC, QI-Meds reduced the number of depression burden days by 50 ( p = 0.038; corresponding to 0.027 to 0.055 QALYs and costs per QALY of $7756 to $15,512) and QI-Therapy by 51 ( p = 0.014; corresponding to 0.028 to 0.056 QALYs and costs per QALY of $4920 to $9841). Among men, QI-Meds increased days of employment by 6 (NS) and QI-Therapy by 37 days ( p = 0.022), over 2 years. Among women, QI-Meds increased days of employment by 26 days ( p = 0.0245), while QITherapy was estimated to increase employment by 14 days (NS).
4. Discussion This paper evaluated cost effectiveness of improving care for depression, examining male and female patients separately. Among men, QI-Therapy led to substantial clinical improvement; however, it also increased health care costs over 24 months by around one-third, relative to UC, yielding a relative cost effectiveness towards the upper range of accepted medical interventions (Gold et al., 1996; Tengs et al., 1995). Our results suggest that QI-Meds is not clinically effective, and therefore not cost effective, for depressed men. Among women, QI-Meds and QI-Therapy had comparable effects on depression burden and quality of life. The relative cost effectiveness for both interventions was well within the
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range of other accepted medical interventions, particularly for QI-Therapy due to its relatively small effect on costs. These results are consistent with our findings for the overall study sample, except for the more disappointing effects of QI-Meds among depressed men (Schoenbaum et al., 2001; Wells et al., 2000). However, most QI studies have not had sufficient sample sizes to examine differential effectiveness among demographic groups, and particularly, to estimate intervention effectiveness for depressed men. Therefore, we do not know if our results of differential effectiveness of QI-Meds by gender are unique to PIC. As QIMeds, given its focus on enhancing medication management while permitting access to psychotherapy, seems more likely than QI-Therapy to be considered for use in primary care, it is important to note the positive results of QI-Therapy for both men and women. Employment is an important outcome in its own right for patients and payers, and it may not be fully captured in standard measures of QALYs (Gold et al., 1996). Intervention effects on employment were particularly large for men under QI-Therapy, with the increase relative to UC corresponding to more than 7 work weeks over 2 years; for women under QIMeds, the increase corresponded to more than 5 work weeks. The point estimate for employment effects under QI-Therapy for women was still qualitatively important – 14 days, or around 3 work weeks – but statistical precision was lower. The relationships between improved depression care, clinical improvement, and labor supply warrant additional study. There are several limitations to this study. First, because our cost estimates lack precision, the study may not have the power to detect subgroup differences in costs or outcomes between men and women. Second, outcomes are self-reported and may be subject to recall bias; any such bias, however, should be equivalent across intervention groups and should not bias estimates of intervention effects. Third, we studied only six practice networks; although they were chosen to be diverse, they may not be representative of all practice networks. Fourth, our study population includes only patients who sought health care (although not necessarily depression care) from a primary care provider; this covers approximately 80% of depressed patients (Young et al., 2001). Finally, while
each intervention had several components, the current design does not allow us to identify the effects of individual components. Thus, we do not know whether the positive outcomes of QI-Therapy for men are attributable to psychotherapeutic treatment generally, the particular form of therapy (i.e., CBT), the quality of provider training, the reduced copayments for psychotherapy from study-trained providers, or other factors. Similarly, we do not understand why QI-Meds was effective for women but not for men, nor why QIMeds yielded larger improvements in women’s labor supply than did QI-Therapy. Additional information on these issues may help guide efforts to further improve the effectiveness and cost effectiveness of depression treatment, for all types of patients.
Acknowledgements This work was funded by the National Institutes of Mental Health (R01MH64658, P50MH54623), the Agency for Healthcare Research and Quality (R01HS08349), and the John D. and Catherine T. MacArthur Foundation (Grant No. 96-42901A-HE).
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