RESUMO
BACKGROUND: The current various case-finding instruments for detecting depression in Korea are too cucumbersome and time-consuming for routine use in primary care or student and soldier groups because of too many questions. We carried out this study in order to investigate the validity of the two-question case-finding instrument for detecting depression easily in the primary care or the mentioned groups. METHODS: We selected one boy high school in Seoul and 155 sophomer students answered the questionnaire by self-report. The questionnaire included two questions about depressed mood and anhedonia: (1) "During the past month, have you often been bothered by feeling down, depressed or hopeless?" (2) "During the past month, have you often been bothered by little interest or pleasure in doing things(e.g., studying, playing or talking with friends) ?". And then a resident of family medicine interviewed them and made a diagnosis for depression using the diagnostic criteria of DSM-IV. Simultaneously we compared the test characteristics of a two-question case-finding instrument with those of a previously validated Beck Depression Inventory as a currently world-wide used screening instrument for depression. RESULTS: The prevalence of major depression as determined by the interview was 6.6%(10 of 151). The two-question case finding instrument had a Cronbach's alpha of 0.663-internal consistency, a sensitivity of 100%, a specificity of 54.6%, a positive likelihood ratio of 2.20 and a negative predictive value of 1.00.(A "yes" answer to either of the two questions was considered a positive test.) And the BDI had a sensitivity of 90%, a specificity of 68.1%, a positive likelihood ratio of 3.63 and a negative predictive value of 0.99(cut-off point=15). Area under the ROC curves of the two-question case-finding instrument was 0.882, greater than that of the BDI, 0.834. CONCLUSIONS: The test characteristics of a two-question case-finding instrument were higher compared to those of BDI for major depression. Therefore, the two-question case-finding instrument is a useful measure for detecting depression and less time-consuming in primary care and certain groups.