Detecting and monitoring depression with a two-item questionnaire (PHQ-2)
Received 30 March 2004; accepted 22 September 2004.
Abstract
Objective
This study evaluates the two-item Patient Health Questionnaire (PHQ-2) as a measure for diagnosing and monitoring depression.
Methods
We assessed construct validity in a cross-sectional sample of 1619 medical outpatients (mean age 43±14 years, 64% female) by comparing the PHQ-2 to four longer self-report questionnaires. Criterion validity was established in a subsample of 520 participants with reference to the Structured Clinical Interview for DSM-IV (SCID). Sensitivity to change was investigated in a prospective study of 167 patients who completed the SCID both at baseline and the 1-year follow-up.
Results
With reference to the SCID, the PHQ-2 had a sensitivity of 87% and a specificity of 78% for major depressive disorder and a sensitivity of 79% and a specificity of 86% for any depressive disorder. Its diagnostic performance was comparable with that of longer depression scales. PHQ-2 change scores accurately reflected improved, unchanged, and deteriorated depression outcomes.
Conclusion
The PHQ-2 performed favorably with respect to a standard diagnostic interview, as well as established depression scales and proved sensitive to change. Thus, the PHQ-2 appears promising as a brief multipurpose measure for detecting depression, grading its severity, and monitoring outcomes over time.
aDepartment of General Internal and Psychosomatic Medicine, University of Heidelberg Medical Center, Im Neuenheimer Feld 410, Heidelberg D-69120, Heidelberg, Germany
bRegenstrief Institute, Indiana University School of Medicine, 1050 Wishard Boulevard, Indianapolis, IN 46202, U.S.A.
Corresponding author. Department of General Internal and Psychosomatic Medicine, University of Heidelberg Medical Center, Im Neuenheimer Feld 410, Heidelberg D-69120, Heidelberg, Germany. Tel.: +49 6221 568999; fax: +49 6221 565749.
ABSTRACT