Purpose: Depressive symptoms relapse and remit over time, perhaps differentially by race and income. Few studies have examined whether time-varying depressive symptoms (TVDS) differentially predict mortality. We sought to determine whether race (white/black) and income (</≥$35,000) moderate the association between TVDS and mortality in a large cohort.
Methods: The REGARDS study is a prospective cohort study among community-dwelling U.S. adults aged 45 years or older. Cox proportional hazard models were constructed to separately analyze the association between mortality (all cause, cardiovascular death, noncardiovascular death, and cancer death) and TVDS in race and income stratified models.
Results: Point estimates were similar and statistically significant for white (aHR = 1.24 [95% CI: 1.10, 1.41]), black (aHR = 1.26 [95% CI: 1.11, 1.42]), and low-income participants (aHR = 1.28 [95% CI: 1.16, 1.43]) for the association between TVDS and mortality. High-income participants had a lower hazard (aHR = 1.19 [95% CI: 1.02, 1.38]). Baseline depressive symptoms predicted mortality in blacks only (aHR = 1.17, 95% CI: [1.00, 1.35]).
Conclusions: We found that TVDS significantly increased the immediate hazard of mortality similarly across race and income strata. TVDS may provide more robust evaluations of depression impact compared with the baseline measures, making apparent racial disparities cited in the extant literature a reflection of the imperfection of using baseline measures.
Keywords: CVD mortality; Depressive symptoms; Income; Mortality; REGARDS; Race; Time-varying.
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