Cross validation of a general population survey diagnostic interview: a comparison of CIS-R with SCAN ICD-10 diagnostic categories

Background. Comparisons of structured diagnostic interviews with clinical a ssessments in general population samples show marked discrepancies. In orde r to validate the CIS-R, a fully structured diagnostic interview used for t he National Survey of Psychiatric Morbidity in Great Britain, it was compar ed with SCAN, a standard, semi-structured, clinical assessment. Methods. A random sample of 1882 Leicestershire addresses from the Postcode Address File yielded 1157 eligible adults. of these 860 completed the CIS- R; 387 adults scores greater than or equal to 8 on the CIS-R and 205 of the se completed a SCAN reference examination. Neurotic symptoms, in the previo us week and month only, were enquired about. Concordance was estimated for ICD-10 neurotic and depressive disorders, F32 to F42 and for depression sym ptom score. Results. Sociodemographic characteristics closely resembled National Survey and 1991 census profiles. Concordance was poor for any ICD-10 neurotic dis order (kappa = 0.25 (95% CI, 0.1-0.4)) and for depressive disorder (kappa = 0.23 (95% CI, 0-0.46)). Sensitivity to the SCAN reference classification w as also poor. Specificity ranged from 0.8 to 0.9. Rank order correlation fo r total depression symptoms was 0.43 (Kendall's tau b; P < 0.001; N = 205). Discussion. High specificity indicates that the CIS-R and SCAN agree that p revalence rates for specific disorders are low compared with estimates in s ome community surveys. We have revealed substantial discrepancies in case f inding. Therefore, published data on service utilization designed to estima te unmet need in populations requires re-interpretation. The value of large -scale CIS-R survey data can be enhanced considerably by the incorporation of concurrent semi-structured clinical assessments.