Small signal, big noise: performance of the CIDI depression module.

Objectives: With the release of data from the Canadian Community Health Survey: Mental Health and Well-Being (Cycle 1.2), researchers have, for the first time, information on several psychiatric disorders from a nationally representative sample of Canadians residing in households. This survey used the Composite International Diagnostic Interview (CIDI) to identify persons with one or more psychiatric disorders. In this paper, our primary purpose was to evaluate the evidence supporting the validity of the CIDI--that is, the extent to which the depression diagnoses generated by the CIDI reflect true cases of depression.

Method: We conducted a critical review of the CIDI, focusing on the depression module.

Results: Reliability studies indicate that the CIDI performs reliably, as measured by interrater reliability. However, the use of different versions of the CIDI and the occasional exclusion of the Depression module from studies suggest that the reliability of the CIDI Depression module remains unconfirmed. The most critical issue in regard to the CIDI's performance is that clinical samples are used to test validity. A clinical sample has a higher prevalence of depression than a community sample.

Conclusion: The results generated by the CIDI in a community setting likely will have a high false-positive rate, resulting in a falsely elevated prevalence rate. Given the widespread application of the CIDI internationally, addressing the outstanding concerns about validity with proper validation studies should become an international priority.