Validity of the Brazilian version of the Geriatric Depression Scale (GDS) among primary care patients

Abstract

The aim of the present study was to determine the validity of the Brazilian version of the Geriatric Depression Scale (GDS) with 30 (GDS-30), 15 (GDS-15), 10 (GDS-10), 4 (GDS-4) and 1 (GDS-1) items and to calculate the optimum cutoff points for identifying depression among elderly primary care subjects. A cross-sectional study was carried out involving 220 elderly patients recruited from four primary care clinics in northeastern Brazil. The following measurements were obtained: sociodemographic variables, Katz scale of independence in activities of daily living, and the GDS with 30, 15, 10, 4 and 1 item(s). A psychiatrist blinded to the results of the GDS applied the mood module of the Structured Clinical Interview for the DSM-IV for the diagnosis of major depressive episodes as the "gold standard." The use of the cut-off point of 10/11 for the GDS-30 produced sensitivity and specificity rates of 92.0% (95% CI: 70-98) and 79% (95% CI: 73-85), respectively. The positive predictive value (PPV) and the negative predictive value (NPV) were 49% and 98%, respectively. The optimum cut-off point for the GDS-15 was 4/5, at which sensitivity was 87% (95% CI: 71-95) and specificity was 82% (95% CI: 76-91), PPV was 51% and NPV was 97%. At the cut-off point of 3/4 the sensitivity, specificity, PPV and NPV for the GDS-10 were 76% (95% CI: 60-89), 81% (95% CI: 75-87), 46% (95% CI: 33-59%), and 94% (95% CI 89-97%), respectively. The optimum cut-off point for the GDS-4 was 0/1, at which sensitivity was 84% (95% CI: 68-93%); specificity was 75% (95% CI; 68-91%); PPV was 41% and NPV was 96%. For the GDS-1, sensitivity was 47%, specificity was 96%; PPV was 69% and NPV was 90%. The GDS-30, GDS-15, GDS-10 and GDS-4 proved to be good screening instruments for depression in primary care clinics in Brazil, whereas the GDS-1 failed to perform adequately.