Minor depression and functional impairment

OBJECTIVE: To describe a method of assessing minor depression and its effects on functional status, medical co-morbidity, seasonality, and demographic variables. DESIGN: A survey administered to a nonrandom sample of 302 patients. SETTING: A university-based family practice outpatient center. PATIENTS: Patients who were seen for routine ambulatory care were asked to complete the Inventory to Diagnose Depression scale and a modified version of the Dartmouth COOP Functional Assessment Charts, including a measure of seasonality. MAIN OUTCOME MEASURES: Six categories of functional impairment were examined across two categories of depression (major and minor) and the nondepressed. Major depression is defined strictly by criteria in the Diagnostic and Statistical Manual of Mental Disorders, Revised Third Edition. Minor depression is defined as depressed mood or anhedonia and one other of the nine depression symptoms. RESULTS: Forty-seven patients (15.6%) had minor depression. Using chi 2 analysis, significant differences were found among the three levels of depression for each functional status category. Logistic regression analysis showed patients with minor depression to have greater odds of more impairment in feelings (odds ratio OR, 4.01; 95% confidence interval CI, 1.75 to 9.19), pain (OR, 2.58; 95% CI, 1.18 to 5.63), and social activities (OR, 2.48; 95% CI, 1.19 to 5.17) compared with the nondepressed patient. The cluster of impairment distinguishing minor from major depression differed somewhat, with more impairment in daily activities (OR, 19.6; 95% CI, 3.45 to 112.00) and feelings (OR, 24.4; 95% CI, 1.78 to 333.00) and greater lung disease (OR, 13.7; 95% CI, 2.19 to 80.00) and seasonality (OR, 5.9; 95% CI, 1.10 to 32.1 for highest seasonality) in patients with major depression. CONCLUSIONS: There appears to be significant functional disability associated with the presence of minor depression. Seasonality was also present in those with minor depression, although it was of greater importance among those with major depression. Despite lack of national consensus on the definition of minor depression, limitations owing to sampling method, and statistical modeling, there is evidence that patients with minor depression reveal a different constellation of impairment than do those with major depressive disorder.