Validation of the PHQ-9 as a screening instrument for depression in diabetes patients in specialized outpatient clinics
1 Department of Diagnostics and Treatment of Common Mental Disorders, Trimbos-Institute, PO Box 725, 3500 AS Utrecht, the Netherlands
2 Department of Psychology and Psychiatry, ZGT Almelo, PO Box 7600, 7600 SZ Almelo, the Netherlands
3 Department of Internal Medicine, ZGT Hengelo, PO Box 546, 7550 AM Hengelo, the Netherlands
4 Institute for Medical Technology Assessment. Erasmus MC, University Medical Centre Rotterdam Burgemeester Oudlaan 50, PO Box 1738, 3000 DR Rotterdam, The Netherlands
5 Department of Psychiatry, VU University Medical Centre, De Boelelaan 1117, PO Box 7057, 1007 MB Amsterdam, The Netherlands
6 Deptartment of Developmental, Clinical and Cross-cultural Psychology, University of Tilburg, PO Box 90153, 5000 LE Tilburg, the Netherlands
BMC Health Services Research 2010, 10:235 doi:10.1186/1472-6963-10-235Published: 12 August 2010
For the treatment of depression in diabetes patients, it is important that depression is recognized at an early stage. A screening method for depression is the patient health questionnaire (PHQ-9). The aim of this study is to validate the 9-item Patient Health Questionnaire (PHQ-9) as a screening instrument for depression in diabetes patients in outpatient clinics.
197 diabetes patients from outpatient clinics in the Netherlands filled in the PHQ-9. Within 2 weeks they were approached for an interview with the Mini Neuropsychiatric Interview. DSM-IV diagnoses of Major Depressive Disorder (MDD) were the criterion for which the sensitivity, specificity, positive- and negative predictive values and Receiver Operator Curves (ROC) for the PHQ-9 were calculated.
The cut-off point of a summed score of 12 on the PHQ-9 resulted in a sensitivity of 75.7% and a specificity of 80.0%. Predictive values for negative and positive test results were respectively 93.4% and 46.7%. The ROC showed an area under the curve of 0.77.
The PHQ-9 proved to be an efficient and well-received screening instrument for MDD in this sample of diabetes patients in a specialized outpatient clinic. The higher cut-off point of 12 that was needed and somewhat lower sensitivity than had been reported elsewhere may be due to the fact that the patients from a specialized diabetes clinic have more severe pathology and more complications, which could be recognized by the PHQ-9 as depression symptoms, while instead being diabetes symptoms.