title: Screening for major depression in cancer outpatients: the diagnostic accuracy of the 9-item patient health questionnaire.
abstract: BACKGROUND
  Systematic screening for depression has been recommended for patients who have medical conditions like cancer. The 9-item Patient Health Questionnaire (PHQ-9) is becoming widely used, but its diagnostic accuracy has not yet been tested in a cancer patient population. In this article, the authors report on the performance of the PHQ-9 as a screening instrument for major depressive disorder (MDD) in patients with cancer.
  
  
  METHODS
  Data obtained from a depression screening service for patients who were attending clinics of a Regional Cancer Centre in Edinburgh, United Kingdom were used. Patients had completed both the PHQ-9 and a 2-stage procedure to identify cases of MDD. Performance of the PHQ-9 in identifying cases of MDD was determined using receiver operating characteristic (ROC) analysis.
  
  
  RESULTS
  Data were available on 4264 patients. When scored as a continuous measure, the PHQ-9 performed well with an area under the ROC curve of 0.94 (95% confidence interval [CI], 0.93-0.95). A cutoff score of ≥ 8 provided a sensitivity of 93% (95% CI, 89%-95%), a specificity of 81% (95% CI, 80%-82%), a positive predictive value (PPV) of 25%, and a negative predictive value (NPV) of 99% and could be considered optimum in a screening context. The PHQ-9 did not perform as well when it was scored using an algorithm with a sensitivity of 56% (95% CI, 55%-57%), a specificity of 96% (95% CI, 95%-97%), a PPV of 52%, and an NPV of 97%.
  
  
  CONCLUSIONS
  The PHQ-9 scored as a continuous measure with a cutoff score of ≥ 8 performed well in identifying MDD in cancer patients and should be considered as a screening instrument in this population.
authors.affiliation: Psychological Medicine Research, University of Edinburgh Cancer Research Center, University of Edinburgh, Edinburgh, United Kingdom. parvez.thekkumpurath@ed.ac.uk
authors.forename: Parvez
authors.initials: P
authors.lastname: Thekkumpurath
authors.forename: Jane
authors.initials: J
authors.lastname: Walker
authors.forename: Isabella
authors.initials: I
authors.lastname: Butcher
authors.forename: Laura
authors.initials: L
authors.lastname: Hodges
authors.forename: Annet
authors.initials: A
authors.lastname: Kleiboer
authors.forename: Mark
authors.initials: M
authors.lastname: O'Connor
authors.forename: Lucy
authors.initials: L
authors.lastname: Wall
authors.forename: Gordon
authors.initials: G
authors.lastname: Murray
authors.forename: Kurt
authors.initials: K
authors.lastname: Kroenke
authors.forename: Michael
authors.initials: M
authors.lastname: Sharpe
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003865:Major Depressive Disorder / Q000175:diagnosis*; D005260:Female; D006305:Health Status Indicators; D006801:Humans; D008297:Male; D008875:Middle Aged; D009369:Neoplasms / Q000523:psychology*; D011795:Surveys and Questionnaires