Validation of Zung's Self-rating Depression Scale among the Colombian general population

In this study we aimed to validate Zung’s Self-rating Depression Scale (SDS; 1965) among Colombian people living in Bucaramanga, Colombia. Although used frequently in Colombian investigations to identify depressive disorders, the SDS had not been validated formally among the general Colombian population. Participants were a random sample of people dwelling in an urban area, with a mean age of 37.4 years (SD = 12.7). Participants filled out the SDS, and were then interviewed by psychiatrists using the Structured Clinical Interview for DSM-IV Axis I Disorders (SCID-I; First, Spitzer, Gibbon, & Williams, 1999) to diagnosis a major depressive episode (MDE) during the last month. Forty was taken as a cut-off point. SDS scores ranged from 21 to 62 (M = 36.5, SD = 9.1). Using the SDS, 95 (35.7%) persons reported clinically meaningful depressive symptoms. The SCID-I interview identified 44 (16.5%) persons with MDE. Cronbach’s alpha was 0.832. The sensitivity was 88.6% (95% CI 74.6-95.7), the specificity 74.8% (95% CI 68.4-80.2), the positive predictive value 41.1% (95% CI 31.2-51.6), the negative predict value 97.1% (95% CI 92.9-98.9), half Cohen’s kappa coefficient 0.433 (95% CI 0.327-0.539), and area under ROC curve 0.901 (95% CI 0.857-0.945). The SDS was found to be a useful tool for screening MDE among the general community.