Identification of depression in diabetes the efficacy of PHQ-9 and HADS-D

Background
Clinical guidelines advise screening for depression in patients with diabetes. The Patient Health Questionnaire (PHQ-9) and the depression subscale of the Hospital Anxiety and Depression Scale (HADS-D) are commonly used in primary care.

Aim
To compare the efficacy of HADS-D and PHQ-9 in identifying moderate to severe depression among primary care patients with type 2 diabetes.

Design of study
Self-report postal survey, clinical records assessed by GPs.

Setting
Seven metropolitan and rural general practices in Victoria, Australia.

Method
Postal questionnaires were sent to all patients with diabetes on the registers of seven practices in Victoria. A total of 561 completed postal questionnaires were returned, giving a response rate 47%. Surveys included demographic information, and history of diabetes and depression. Participants completed both the PHQ-9 and HADS-D. Clinical data from patient records included glycosylated hemoglobin (HbA1c) levels and medications.

Results
The proportion of the total sample completing HADS-D was 96.8% compared with 82.4% for PHQ-9. Level of education was unrelated to responses on the HADS-D but was related to completion of the PHQ-9. Using complete data (n = 456) from both measures, 40 responders showed HADS-D scores in the moderate to severe range, compared with 103 cases identified by PHQ-9. Only 35 cases were classified in the moderate to severe category by both the PHQ-9 and HADS-D. Items with the highest proportions of positive responses on the PHQ-9 were related to tiredness and sleeping problems and, on the HADS-D, feeling slowed down.

Conclusion
It may be that the items contributing to the higher prevalence of moderate to severe depression using the PHQ-9 are due to diabetes-related symptoms or sleep disorders.