Background: Despite the high prevalence and morbidity of minor and subsyndromal depression in primary care elderly people, there are few data to identify those at highest risk of poor outcomes. The goal of this observational cohort study was to characterize the one-year outcomes of minor and subsyndromal depression, examining the predictive strength of a range of putative risks including clinical, functional and psychosocial variables.
Methods: Patients aged ≥ 65 years were recruited from primary care medicine and family medicine practices. Of 750 enrollees, 484 (64.5%) completed baseline and one-year follow-up assessments of depression diagnosis (major depression vs. minor and subsyndromal depression vs. non-depressed) by the Structured Clinical Interview for DSM-IV, depressive symptom severity (Hamilton Rating Scale for Depression), and validated measures of other predictors.
Results: Patients with baseline minor and subsyndromal depression were more depressed than the non-depressed group at follow-up: They had a 7.0-fold (95% CI 4.5–10.8) risk of developing major depression, and a one-year adjusted Hamilton Depression Score of 11.0 (95% CI 10.2–11.8) compared with 7.8 (95% CI 7.1–8.5) for the non-depressed group; these outcomes were less severe than those of the major depression group. Independent predictors of depression outcomes included race, psychiatric and physical functioning, and social support.
Conclusions: Minor and subsyndromal depression are likely to persist, and pose an elevated risk of worsening over one year. Clinicians and preventive interventions researchers should focus on modifiable risks, such as psychiatric functioning or social support, in elders suffering clinically significant depressive symptoms.