title: Detecting and monitoring depression with a two-item questionnaire (PHQ-2).
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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of General Internal and Psychosomatic Medicine, University of Heidelberg Medical Center, Im Neuenheimer Feld 410, Heidelberg D-69120, Heidelberg, Germany. bernd.loewe@med.uni-heidelberg.de
authors.forename: Bernd
authors.initials: B
authors.lastname: Löwe
authors.forename: Kurt
authors.initials: K
authors.lastname: Kroenke
authors.forename: Kerstin
authors.initials: K
authors.lastname: Gräfe
mesh_terms: D000328:Adult; D003430:Cross-Sectional Studies; D003866:Depressive Disorder / Q000175:diagnosis* / Q000523:psychology; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D012680:Sensitivity and Specificity; D011795:Surveys and Questionnaires