Structured diagnostic interviews are very time-consuming and therefore increase both the expense and the respondent burden in epidemiologic surveys. A 2-staged interview that screens potential cases before the full diagnostic instrument is administered has the potential to greatly reduce the average interview length. In this paper, we evaluate 2 measures of psychological distress (the Kessler 6- and 10-Item Psychological Distress Scales [K6 and K10]) as potential screening instruments for depression.
We use data from Cycle 1.2 of the Canadian Community Health Survey and receiver operator characteristic analysis to examine the agreement between the K6 and K10 and the World Mental Health Composite International Diagnostic Interview module for major depression (1-month and 12-month estimates).
Of the respondents, 823 were positive for 1-month depression (2.0%; 95% confidence interval [CI], 1.8% to 2.2%), and 1930 were positive for 12-month depression (4.8%; 95%CI, 4.5% to 5.1%). Both the K6 and K10 performed very well as predictors of 1-month depression, with areas under the curve (AUC) of 0.929 (95%CI, 0.908 to 0.949) for the K10 and 0.926 (95%CI, 0.905 to 0.947) for the K6. For 12-month depression, the AUCs remained good at 0.866 (95%CI, 0.848 to 0.883) for the K10 and 0.858 (95%CI, 0.840 to 0.876) for the K6.
Both the K6 and the K10 appear to be excellent screening instruments, especially for current depression. Although performance of the 2 instruments is similar, the K6 is more attractive for use as a screening instrument because of the lower response burden.