When MDD affects African Americans and Caribbean blacks, it is usually untreated and is more severe and disabling compared with that in non-Hispanic whites. The burden of mental disorders, especially depressive disorders, may be higher among US blacks than in US whites.

Lifetime prevalence estimates of psychosis in community samples are strongly influenced by methods of assessment and diagnosis. Although results using computer algorithms were similar in the National Comorbidity Survey and Epidemiologic Catchment Area studies, diagnoses so obtained agreed poorly with clinical diagnoses. Accurate assessment of psychotic illness in epidemiologic samples may require collection of extensive contextual information for clinician review.

An overview is presented of the rationale, design, and analysis plan for the WMH-CIDI clinical calibration studies. As no clinical gold standard assessment is available for the DSM-IV disorders assessed in the WMH-CIDI, we adopted the goal of calibration rather than validation; that is, we asked whether WMH-CIDI diagnoses are 'consistent' with diagnoses based on a state-of-the-art clinical research diagnostic interview (SCID; Structured Clinical Interview for DSM-IV) rather than whether they are 'correct'. Consistency is evaluated both at the aggregate level (consistency of WMH-CIDI and SCID prevalence estimates) and at the individual level (consistency of WMH-CIDI and SCID diagnostic classifications). Although conventional statistics (sensitivity, specificity, Cohen's kappa) are used to describe diagnostic consistency, an argument is made for considering the area under the receiver operator curve (AUC) to be a more useful general-purpose measure of consistency. In addition, more detailed analyses are used to evaluate consistency on a substantive level. These analyses begin by estimating prediction equations in a clinical calibration subsample, with WMH-CIDI symptom-level data used to predict SCID diagnoses, and using the coefficients from these equations to assign predicted probabilities of SCID diagnoses to each respondent in the remainder of the sample. Substantive analyses then investigate whether estimates of prevalence and associations when based on WMH-CIDI diagnoses are consistent with those based on predicted SCID diagnoses. Multiple imputation is used to adjust estimated standard errors for the imprecision introduced by SCID diagnoses being imputed under a model rather than measured directly. A brief illustration of this approach is presented in comparing the precision of SCID and predicted SCID estimates of prevalence and correlates under varying sample designs.

This paper reports the results of methodological studies carried out in conjunction with the US National Comorbidity Survey (NCS) to evaluate Version 1.0 of the World Health Organization (WHO) Composite International Diagnostic Interview (CIDItured instrument like the CIDI in the NCS because of the large sample size, the enormous geographic dispersion of the sample, and the prohibitive costs and logistic complications of the study. The NCS was the first large-scale general population survey to administer the CIDI in the United States. Although WHO CIDI Field Trials carried out prior to the NCS documented good performance of the instrument (Wittchen 1994), the field trials were conducted largely in clinical samples and administered in clinical settings. As a result, we considered it very important to carry out pretests before using the instrument in a community sample.As described more fully below, the NCS pretests were guided by the literature on survey data collection methodology (e.g. Bradburn et al. 1979; Moss and 33

The type of bipolar disorder examined here is highly chronic, co-morbid and impairing. Increased efforts are required to attract current cases into appropriate treatment. Methodological research is needed to develop more accurate measures of other bipolar symptom profiles for use in general population epidemiological studies.