Assessment of physical etiologies for mood and anxiety disorders in structured diagnostic interviews

Background Structured diagnostic interviews include items that evaluate physical etiologies for mood and anxiety disorders. The objective of this article was to assess the impact of such items. Method A mental health survey in Canada collected data from n = 36,984 household residents. The lifetime prevalence of mood and anxiety disorders was calculated with and without exclusions due to physical causes. Results Approximately 10% of subjects with a lifetime depressive disorder reported that all of their episodes were due to one or more physical cause. Many of the reported etiologies were implausible given the DSM-IV requirement that the disturbance be a ‘‘direct physiological consequence’’ of the physical cause. The results were similar for manic episodes and anxiety disorders. Conclusions Structured diagnostic interviews assess physical etiologies in ways that are subject to inconsistency and inaccuracy. Physical etiology items may bias estimates by introducing etiological opinions into the assessment of disorder frequency.