Lifetime diagnoses were utilized for all analyses of both the NCS and NCS-R datasets. Diagnoses for the two datasets are based on the World Mental Health Survey Initiative Version of the World Health Organization Composite International Diagnostic Interview (WMH-CIDI [22] a structured interview protocol. The version used in the NCS yielded DSM-IIIR [23] diagnoses and the version used in the NCS-R yielded DSM-IV [24] diagnoses. Further details regarding the assessment procedures for each sample are reported elsewhere [17, 19]. Given that the central aim of the study was to characterize patterns of comorbidity, non-hierarchical diagnoses were utilized.
