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

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.

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.

The internal consistency (Cronbach's α) 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 HbA1c whereas the glycemic differences were not significant when using CES-D.

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.