title: Optimal cut-off score for diagnosing depression with the Patient Health Questionnaire (PHQ-9): a meta-analysis.
abstract: BACKGROUND
  The brief Patient Health Questionnaire (PHQ-9) is commonly used to screen for depression with 10 often recommended as the cut-off score. We summarized the psychometric properties of the PHQ-9 across a range of studies and cut-off scores to select the optimal cut-off for detecting depression.
  
  
  METHODS
  We searched Embase, MEDLINE and PsycINFO from 1999 to August 2010 for studies that reported the diagnostic accuracy of PHQ-9 to diagnose major depressive disorders. We calculated summary sensitivity, specificity, likelihood ratios and diagnostic odds ratios for detecting major depressive disorder at different cut-off scores and in different settings. We used random-effects bivariate meta-analysis at cutoff points between 7 and 15 to produce summary receiver operating characteristic curves.
  
  
  RESULTS
  We identified 18 validation studies (n = 7180) conducted in various clinical settings. Eleven studies provided details about the diagnostic properties of the questionnaire at more than one cut-off score (including 10), four studies reported a cut-off score of 10, and three studies reported cut-off scores other than 10. The pooled specificity results ranged from 0.73 (95% confidence interval [CI] 0.63-0.82) for a cut-off score of 7 to 0.96 (95% CI 0.94-0.97) for a cut-off score of 15. There was major variability in sensitivity for cut-off scores between 7 and 15. There were no substantial differences in the pooled sensitivity and specificity for a range of cut-off scores (8-11).
  
  
  CONCLUSIONS
  The PHQ-9 was found to have acceptable diagnostic properties for detecting major depressive disorder for cut-off scores between 8 and 11. Authors of future validation studies should consistently report the outcomes for different cut-off scores.
authors.affiliation: Department of Health Sciences, York University, York, UK. lem514@york.ac.uk
authors.forename: Laura
authors.initials: L
authors.lastname: Manea
authors.forename: Simon
authors.initials: S
authors.lastname: Gilbody
authors.forename: Dean
authors.initials: D
authors.lastname: McMillan
mesh_terms: D003865:Major Depressive Disorder / Q000175:diagnosis* / Q000523:psychology; D006801:Humans; D016017:Odds Ratio; D011569:Psychiatric Status Rating Scales / Q000592:standards; D011594:Psychometrics; D012372:ROC Curve; D012680:Sensitivity and Specificity; D011795:Surveys and Questionnaires