The impact of substance induced and general medical condition exclusion criteria on the prevalence of common mental disorders as defined by the CIDI

Abstract

Objectives: It has been previously argued that the methodology employed by the Composite International Diagnostic Interview version 2.1 to assess the substance induced and general medical condition exclusion criteria are inadequate. As a result prevalence estimates generated from epidemiological studies using this interview may be underestimated. The purpose of the current study was to examine the substance induced and general medical condition exclusion criteria in the Australian National Survey for Mental Health and Well-being and determine the impact they have on prevalence estimates of the common mental disorders. Method: Data from the 1997 Australian National Survey of Mental Health and Wellbeing were analyzed. Frequencies were generated as an indication of how many respondents believed their psychiatric symptoms were always due to a substance or general medical condition. New DSM-IV prevalence estimates were calculated ignoring the application of the substance induced and general medical condition exclusion criteria and compared to standard DSM-IV prevalence estimates. Results: The effect of the substance induced and general medical condition exclusion criteria on final prevalence rates were minimal with around a 0.1% increase when the exclusions were ignored. This equates to a relative difference ranging from no difference for Generalized Anxiety Disorder to an increase of 12% of the base prevalence estimate for Agoraphobia. Conclusions: In surveys that use the Composite International Diagnostic Interview version 2.1 the substance induced and general medical condition exclusion criteria have a minor impact on determining final case definition in the majority of mental disorders.