Usefulness of the zung self-rating depression scale for schizophrenics.

OBJECTIVE This study was performed to provide psychometric data concerning the Zung Self-Rating Depression Scale (SDS) when administered to schizophrenics. METHODS The subjects were 110 schizophrenic inpatients (50 females and 60 males) who were diagnosed according to the DSM-IV criteria for schizophrenia. Informed consent was obtained from all subjects. RESULTS 1) Cronbach's alpha for the SDS was .81, and reached the acceptable range for internal consistency. 2) Test-retest reliability coefficient for the total SDS was comparatively high (Spearman's rho = .87, p < .001, N = 19), but those for SDS items revealed variability among items. 3) The mean total SDS score for the 15 patients with depression was significantly different from the group of patients without depression. 4) None of the 20 items or total SDS was significantly correlated with extrapyramidal symptoms. CONCLUSIONS Overall, the findings demonstrate the usefulness of the SDS for schizophrenics. However, due to findings of mixed reliability, caution should be exercised when using the SDS for these patients.