Validation of the PHQ-9 as a screening instrument for depression in diabetes patients in specialized outpatient clinics.
BACKGROUND
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.


METHODS
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.


RESULTS
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.


CONCLUSIONS
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.
van Steenbergen-Weijenburg
Kirsten M
KM
Department of Diagnostics and Treatment of Common Mental Disorders, Trimbos-Institute, PO Box 725, 3500 AS Utrecht, the Netherlands. Ksteenbergen@trimbos.nl
de Vroege
Lars
L
Ploeger
Robert R
RR
Brals
Jan W
JW
Vloedbeld
Martijn G
MG
Veneman
Thiemo F
TF
Hakkaart-van Roijen
Leona
L
Rutten
Frans F J
FF
Beekman
Aartjan T F
AT
van der Feltz-Cornelis
Christina M
CM
D000368:Aged; D000554:Ambulatory Care Facilities; D003865:Major Depressive Disorder / Q000150:complications / Q000175:diagnosis*; D048909:Diabetes Complications; D005189:False Positive Reactions; D005260:Female; D006801:Humans; D007406:Interview, Psychological; D008297:Male; D008403:Mass Screening / Q000295:instrumentation*; D008875:Middle Aged; D009426:Netherlands