• Lesley Stafford, Michael Berk, and Henry J Jackson.
• Department of Psychology, School of Behavioural Science, University of Melbourne, Victoria 3010, Australia. lesley.liebowitz@bigpond.com
• Gen Hosp Psychiatry. 2007 Sep 1;29(5):417-24.

ObjectiveDepression is common but frequently undetected in patients with coronary artery disease (CAD). Self-report screening instruments for assessing depression such as the Hospital Anxiety and Depression Scale (HADS) and the Patient Health Questionnaire-9 (PHQ-9) are available but their validity is typically determined in depressed patients without comorbid somatic illness. We investigated the validity of these instruments relative to a referent diagnostic standard in recently hospitalized patients with CAD.MethodThree months post-discharge for a cardiac admission, 193 CAD patients completed the HADS and PHQ-9. The Mini International Neuropsychiatric Interview (MINI) was the criterion standard. Scale reliability was calculated using Cronbach's alpha. Convergent validity was computed using Pearson's intercorrelations. Sensitivity and specificity for various cut-off scores for both measures and for the PHQ-9 categorical algorithm were calculated using receiver operating characteristics (ROC). For analyses, participants were assigned to two groups, 'major depressive disorder' or 'any depressive disorder'.ResultsFor all calculations, alpha was 0.05 and tests were two-tailed. Internal consistencies for the two measures were excellent. Criterion validity for the PHQ-9 and HADS was good. We found no statistical differences between the PHQ-9 and HADS for detecting either group; however, the categorical algorithm of the PHQ-9 for diagnosing major depression had a superior LR+ when compared with the summed HADS or PHQ-9. The operating characteristics of the screening instruments for 'any depressive disorder' were slightly lower than for 'major depressive disorder'. Some optimum cut-off scores were lower than the generally recommended cut-off scores, particularly when screening for major depression (e.g., > or = 5/6 vs. > or = 10 and > or = 8 for PHQ-9 and HADS, respectively). Lowering the cut off scores substantially improved the sensitivity of these instruments while retaining specificity, thereby improving their usefulness to screen for CAD patients with depression.ConclusionsBoth instruments have acceptable properties for detecting depression in recently hospitalized cardiac patients, and neither scale is statistically superior when summed scores are used. The categorical algorithm of the PHQ-9 for diagnosing major depression has a superior LR+ compared to the summed PHQ-9 and HADS scores. Use of the generally recommended cut-off scores should be cautious. In light of the aversive outcomes associated with depression in CAD, screening for depression is a clinical priority.

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