Background: The Internet offers promising possibilities for the quick screening of depression for treatment and research purposes. This paper aims to validate three self-rated measures to screen for depression on the Internet: SID (single-item depression scale), CES-D (Center for Epidemiological Studies Depression scale) and K10 (Kessler psychological distress scale).
Methods: Of the 502 subjects aged 18-80 who rated the SID, CES-D and K10 measures on the Internet, 157 (31%) subjects were also interviewed by telephone using the WHO Composite International Diagnostic Interview (C)IDI) for DSM-IV-disorders.
Results: Cronbach's alpha for both web self-rated measures CES-D and K10 was 0.90. The SID correlated 0.68 (P<0.001) with the CES-D and with the K10. The CES-D correlated 0.84 with the K10 (P<0.001). Subjects with a DSM-IV diagnosis for any depressive disorder had significantly higher means (P<0.001) on the three self-rated measures for depressive symptoms than subjects without a diagnosis of any depressive disorder. Using any depressive disorder as the gold standard, the area under the curve (AUC) of the SID was 0.71 (95% CI: 0.63-0.79), which was significantly lower than the AUC of the CES-D (AUC: 0.84; 95% CI: 0.77-0.90, P=0.003) and of the K10 (AUC: 0.81; 95% CI: 0.73-0.88, P=0.0024). The AUCs for the K10 and CES-D did not differ significantly from each other.
Limitations: The CIDI interviews were not recorded, so inter-rater reliability could not be calculated.
Conclusions: The CES-D and K10 are reliable, valid tools for care providers to quickly screen depressive patients on the Internet and for researchers to collect data.
Copyright (c) 2009 Elsevier B.V. All rights reserved.