Abstract
Objective:
Psychological distress questionnaires are often used as screening instruments for mental disorders in clinical and epidemiologic settings. Poor physical health may affect the screening properties of a questionnaire. We evaluate the effect of self-perceived health status on the screening performance of the Kessler K10 and K6 scales in a community sample.
Methods:
We used data from the Canadian Community Health Survey: Mental Health and Well-Being (CCHS 1.2). Psychological distress was measured by the 6–item (K6) and the 10–item (K10) Kessler instrument. Depression and anxiety disorders were assessed using the World Mental Health Composite International Diagnostic Interview (1–month estimates). Optimal cut-off points regarding health status were determined by finding the K6 and K10 values that allowed for the best balance between sensitivity and specificity. Stratum-specific likelihood ratios (SSLRs) were computed to define strata with discriminating power.
Results:
There was a strong association between the screening performance of the K6 and K10 scales and self-perceived health status: for the K10 scale, a cut-off point of 5/6 yielded the best balance between sensitivity and specificity for subjects with excellent or very good health status, while a cut-off point of 14/15 yielded the best balance between sensitivity and specificity for subjects with poor health status.
Conclusions:
The combination of the K6 and K10 scales, with a self-rated health status item, may improve screening properties of the 2 scales.