Depression in medical outpatients: use of the Zung scale.

Sixty-nine randomly selected medical outpatients were clinically evaluated for depressive illness. A Zung Self-Rating Depressive Scale (SDS) was also administered to each patient. The prevalence of depression in the sample was 42%. The SDS picked up 30% of those depressed while missing those whose depression was presented under the guise of somatic illness. The SDS is thus a suitable instrument only in screening of the non-depressed medical patients.