RESUMEN
Depressive disorders are quite prevalent among the old population of developed countries, therefore, validated scaling systems are necessary for screening purpose. The present study was designed to develop and validate GDS-15 in Iran. The Persian version was prepared using translation, reverse translation and comparing technique. Then, 204 adults aged >59 years were randomly selected to fill the questionnaire. Standard Clinical Interview using Composite International Diagnostic Interview [CIDI] was applied as the gold standard for depressive disorders diagnosis. Results revealed satisfactory reliability coefficient. Depression-associated factor [including 11 questions] could be considered as a brief form with alpha and correlation coefficient of 0.92 and 0.58 with the original form [p<0.001]. Having applied ROC analysis, cut off points of 8 and 6 were determined for 15- and 11-question forms, respectively, with sensitivities of 0.9 and 0.9 and specificities of 0.84 and 0.83, respectively. Our results revealed that 11- and 15-question forms of GDS are quite reliable and valid for epidemiological and screening studies, especially among urban population