Community versus Clinic Sampling: Effect on the Familial Aggregation of Anxiety Disorders

Clinic versus community sampling affects familial clustering of anxiety disorders. In general, the effect of clinic sampling is likely attributable to the greater severity of clinic cases, which may also be associated with increased familial morbidity. Differences observed between the anxiety disorders may be artifactual because of the diagnostic criteria of the anxiety disorders or low power. This study illustrates the importance of establishing standards for case-control selection, especially as complex disorder genetics moves increasingly toward population-based sampling.