Validation of Beck Depression Inventory (BDI- II) scale for detection of depression among patients with chronic illness at Jimma University Specialized Hospital, Jimma southwestern Ethiopia

Abstract

Background: The Beck Depression Inventory (BDI) is one of the most popular scales not only as one of the most widely used self-report instruments for evaluating the severity of depression, but also for screening of depression in clinical practice and general population. The Beck Depression Inventory-II showed high reliability and good correlation with measures of depression in different settings. Its threshold for detecting depression varied according to the type of patients, suggesting the need for adjusted cut off points. This study was designed with three objectives 1. To evaluate content validity of Beck depression screening tool (BDST) 2. To evaluate criterion validity of BDST against a gold standard (MINI) measure of MDD 3. To evaluate the convergent validity of BDST against functional impairment Methods In this study, Institution based cross-sectional study design was used to assess the criterion, content and convergent validity of the BDI- II against the gold standard measure of depression, the MINI, on people with chronic physical illness who has follow up at Jimma university specialized hospital. The criterion validation was undertaken on 123 people with chronic physical illness. Descriptive analysis covering frequencies, percents, mean, median standard deviation was made to characterize the study population by socio demographic and clinical characteristics. The sensitivities and specificities at different cut of points was determined and the optimal cut off points identified. Convergent validity was also evaluated by using a functional impairment scale (WHODAS). The convergent validity of the BDST was tested using Pearson’s correlation coefficient test between BDST and the functional impairment test. Result The area under receiver operating characteristic curve was 0.90 (95%CI 0.83-0.98) with 87% and 82% sensitivity and specificity at optimal cut off point of 16 respectively. The internal reliability 3 Cronbach's alpha for the BDI-II total score was 0.93. The correlation between the BDI-II and WHODAS was (r=0.71) Conclusion The BDI-II is a reliable screening tool for detection of depressive symptoms among people with chronic physical illness in hospital settings, in Ethiopia with validity comparable to that for international studies. Therefore, the findings can provide basic information for intervention strategies for depression in chronically ill medical patients