Predictive validity of common mental disorders screening questionnaire as a screening instrument in long term sickness absence.

Aims: Screening instruments for detection of common mental disorders have not been validity tested in long term sickness absence (LSA), which is the aim of this study for the Common Mental Disorders Screening Questionnaire (CMD-SQ).

Methods: Of all 2,414 incident persons on continuous sick-leave for more than eight weeks in a Danish population of 120,000 inhabitants 1,121 participated in a two-phased study by being screened for mental disorders by CMD-SQ in Phase 1. A subgroup of 337 was examined by a psychiatrist and diagnosed with Present State Examination in Phase 2. Results performed on Phase 2 were weighted up to Phase 1. Test performance was analyzed by ROC-analyses, and the fraction with a positive screening test, Q, the sensitivity SE, and 1 minus the specificity, SP, were plotted against decreasing cut-point in the tested scales for specific diagnostic groups.

Results: A sub-scale in CMD-SQ, SCL-8AD, compiled of SCL-ANX4, SCL-8, and SCL-DEP6, showed the best psychometric properties in detection of any mental disorder (AUC 0.80). Other scales were tested as well. The psychometric properties were dependent on sex and age. The plots of Q, SE, and 1-SP against decreasing cut-point gave a comprehensive view of the performance of the scales, which could be of significance in addressing the ethical aspects of screening.

Conclusions: SCL-8AD is a promising candidate for the screening of mental disorders in LSA. It is intended to be administered by the social services because in Denmark there is not a legal requirement that sick-listed persons are certified as sick by a physician.