OBJECTIVE: The authors examined the clinical significance of depressive
symptoms below the threshold for depressive disorder in outpatient samples.
METHOD: The subjects were 775 adult patients with current depressive
disorder, 1,420 patients with subthreshold depression, and 1,767
hypertensive patients with and without depression, all of whom were
visiting the offices of mental health specialists and general medical care
providers in three U.S. cities. Data on demographic characteristics,
severity of depression, extent of psychiatric and medical comorbidity,
family psychiatric history, and treatment history for the patients with
depressive disorder and those with subthreshold depression were compared.
RESULTS: The percentage of patients with subthreshold depression who had a
family history of depression (41%) was nearly as high as that of the
patients with depressive disorder (59%). The two groups of patients had
similar levels of medical and psychiatric comorbidity except for anxiety
disorders, which were greater among the patients with depressive disorder.
Among the hypertensive patients in the general medical sector, those with
subthreshold depression were more similar to those with depressive disorder
than to the nondepressed hypertensive patients. Treatment rates were
considerably lower for patients with subthreshold depression than for
patients with depressive disorder in the general medical sector, but they
were similar in the mental health specialty sector. CONCLUSIONS: In these
outpatients, subthreshold depression appeared to be a variant of affective
disorder and was treated as such in the mental health specialty sector but
not in the general medical sector. The findings emphasize the importance of
treatment outcome studies of patients with subthreshold depression.