The predictive validity of lay Diagnostic Interview Schedule diagnoses in the general population. A comparison with physician examiners.

A clinical reexamination by psychiatrists is a useful comparison for exploring lay Diagnostic Interview Schedule-derived psychiatric diagnoses in general population surveys, but as a validity standard psychiatric reexamination is less than ideal. There are many potential sources of disagreement that have nothing to do with the validity of either the lay or the psychiatrist examination. Another approach to comparing lay and psychiatrist diagnoses is to examine their relative predictive power. We describe such a comparison using outcome variables derived from the one-year follow-up examination of Epidemiologic Catchment Area respondents done at the St. Louis site. We examine several outcome variables across nine diagnostic categories. Within the limits of the available data, lay and psychiatrist diagnoses appear to be essentially equal in terms of the number of outcomes better predicted and few of the differences in predictive power approach statistical significance. We discuss the implications of these findings for the analysis of lay interviewer Diagnostic Interview Schedule-derived diagnoses.