Abstract
OBJECTIVES: To estimate the effects of depression diagnosis and antidepressant treatment on 2-year all-cause mortality in Medicare beneficiaries with chronic obstructive pulmonary disease (COPD) and determine whether Social Security Disability Insurance (SSDI) eligibility modifies these relationships. DESIGN: Retrospective cohort study. SETTING: A 5% random sample of Medicare beneficiaries aged 65 and older in stand-alone Part D plans in 2006 to 2008. PARTICIPANTS: Beneficiaries diagnosed with COPD and continuously enrolled in Medicare Parts A, B, and D (N = 75,699). MEASUREMENTS: Depression diagnosis was assessed at baseline (2006). Evidence of antidepressant treatment was measured across time. Covariates included baseline characteristics, comorbidities, and disease severity. Survival analyses using Cox proportional hazards models estimated 2-year mortality associated with depression diagnosis or antidepressant treatment (in beneficiaries with depression). Interaction terms of SSDI eligibility with baseline depression and time-dependent antidepressant treatment were tested. RESULTS: More than one-fifth (21.6%) of beneficiaries with COPD had a depression diagnosis at baseline, and 82.1% of those received antidepressants. Nearly one-sixth (16.3%) of the sample were SSDI eligible. Baseline depression heightened risk of death (hazard ratio = 1.13, 95% confidence interval = 1.09-1.18) in beneficiaries who were not eligible for SSDI. In beneficiaries with depression, the association between antidepressant treatment and lower mortality was different according to SSDI eligibility status. CONCLUSION: Social Security Disability Insurance eligibility modifies the effects of depression and antidepressant treatment on mortality in Medicare beneficiaries with COPD. These data suggest that clinicians should identify and treat depression in individuals with COPD, but further studies are needed to determine the effect of these interventions.