A comparison of diagnostic interviews for depression in the Stirling County study - Challenges for psychiatric epidemiology

Background: High prevalence rates in psychiatric epidemiologic studies rais e questions about whether data-gathering procedures identify transient resp onses rather than clinical disorders. This issue is explored relevant to de pression using data from the Stirling County Study. Methods: The study's customary method, the DPAX (DP for depression and AX f or anxiety) was compared with the Diagnostic Interview Schedule (DIS), both of which were administered to a sample of 1396 subjects selected in 1992. Reasons for discordance were analyzed, and demographic correlates of respon ses to questions about dysphoria were examined. These lay-administered inte rviews were then compared wi th clinician-administered interviews that used the Structured Clinical Interview for DSM-III-R (SCID) with 139 subjects. The kappa statistic and logistic regression were used for statistical asses sment. Results: For the level of agreement between the DPAX and the DIS for curren t and lifetime depression, kappa = 0.40 and kappa = 0.33, respectively. Sub jects diagnosed only by the DPAX tended to have less education than those d iagnosed only by the DIS. Some idioms for dysphoria seemed to work better t han others. Using SCID interviews as a clinical standard, the DPAX had 15% sensitivity and 96% specificity and the DIS had 25% sensitivity and 98% spe cificity. Conclusions: Comprehension of an interview can be improved by using multipl e questions for dysphoria and a simpler mode of inquiry. Clinician-administ ered interviews tend to corroborate disorders identified in lay-administere d interviews but suggest that survey: methods underestimate prevalence. Fur ther research is needed to evaluate the validity of both types of interview s, but evidence from a 16-year follow-up evaluation indicates that depressi on diagnosed by the DPAX is a serious disorder in terms of morbidity and mo rtality.