The importance of subsyndromal depression in older primary care patients: prevalence and associated functional disability.

OBJECTIVE: Existing diagnostic categories for depression may not encompass the majority of older people suffering clinically significant depressive symptoms. We have described the prevalence of subsyndromal depressive symptoms and tested the hypothesis that patients with subsyndromal depression have greater functional disability and general medical burden than nondepressed subjects but less than patients with diagnosable depressions.
METHODS: Subjects were 224 patients, aged 60 years and older, recruited from private internal medicine offices or a family medicine clinic. Validated measures of psychopathology, medical burden, and functional status were used. The subsyndromal depression group was defined by a score of more than 10 on the Hamilton Rating Scale for Depression and by the absence of major or minor depressive disorder. Analyses included multiple regression techniques to determine the presence of group differences adjusted for demographic covariates.
RESULTS: Subsyndromal depression was common (estimated point prevalence of 9.9% compared with 6.5% for major depression, 5.2% for minor depression, and .9% for dysthymic disorder), associated with functional disability and medical comorbidity to a degree similar to major or minor depression, and often treated with antidepressant medications.
CONCLUSIONS: Although depressive conditions are common and are associated with considerable functional and medical morbidity in older primary care patients, many patients with clinically significant depressive symptoms are not captured by criteria-based syndromic diagnostic categories. Future work should include intervention studies of subsyndromally depressed older persons as well as attention to the course and biopsychosocial concomitants of diagnosable and subsyndromal depressions in this population.