Measuring depression with CES-D in Chinese patients with type 2 diabetes: the validity and its comparison to PHQ-9

Background: The validity of the 20-item Center for Epidemiological Studies Depression (CES-D) scale for depression screening in Hong Kong Chinese patients with type 2 diabetes remains unknown. We aimed to validate CES-D, compare its psychometric properties with the 9-item Patient Health Questionnaire (PHQ-9), and explore whether one of the two is more suitable for depression screening in Chinese patients with type 2 diabetes. Methods: Between June 2010 and July 2011, 545 consecutive Chinese patients with type 2 diabetes who underwent structured comprehensive assessments completed the CES-D and PHQ-9. Forty patients were retested within 2-4 weeks by telephone interview and 97 patients were randomly selected to undergo the Mini International Neuropsychiatric Interview (MINI) by psychiatrists for clinical diagnosis of depression. Results: The internal consistency (Cronbach's a) of CES-D was 0.85, with a test-retest correlation coefficient of 0.64. The area under the curve for CES-D compared to the clinical diagnosis of major depression was 0.85. A cut-off score of >= 21 for CES-D provided the optimal balance between sensitivity (78.3 %) and specificity (74.3 %) and identified 17.8 % (n = 97) of patients with depression. CES-D and PHQ-9 showed moderate agreement in depression screening (Cohen's Kappa: 0.45). Compared to non-depressed patients, those who screened positive by PHQ-9 had a higher HbA(1c) whereas the glycemic differences were not significant when using CES-D. Conclusion: The CES-D is a valid screening tool for depression in Chinese type 2 diabetic patients although the PHQ-9 was more discriminative in identifying those with suboptimal glycemic control.