Diagnostic accuracy, internal consistency, and convergent validity of the Greek version of the patient health questionnaire 9 in diagnosing depression in rheumatologic disorders

Thomas Hyphantis, Konstantinos Kotsis, Paraskevi V. Voulgari, Niki Tsifetaki, Francis Creed, Alexandros A. Drosos

    Research output: Contribution to journalArticlepeer-review

    Abstract

    Objective The Patient Health Questionnaire 9 (PHQ-9) was developed to screen for depressive disorders in community, primary care, and medical settings. We aimed to estimate its diagnostic accuracy, internal consistency, reliability, and convergent validity in diagnosing major depressive disorder (MDD) in Greek patients with rheumatologic disorders. Methods In a 2-phase sampling design study, we recruited 475 patients with established rheumatologic disorders. One of 2 of the high scorers (PHQ-9 score ≥9, n = 85) and 1 of 3 of the low scorers (PHQ-9 score 0-8, n = 128) were interviewed using the Mini International Neuropsychiatric Interview to confirm MDD. A receiver operator characteristic curve analysis was performed to confirm the optimum threshold value. The scale's dimensional structure was tested with factor analysis, and internal consistency reliability was assessed with Cronbach's alpha. Psychological distress (Symptom Check List-90-Revised [SCL-90-R]), disability (Health Assessment Questionnaire disability index), and health-related quality of life (HRQOL; World Health Organization Quality of Life Instrument [WHOQOL-BREF]) were also assessed to test convergent validity with bivariate correlations. Results At an optimum threshold of 10, the PHQ-9 showed a sensitivity of 81.2% and a specificity of 86.8%. The area under the curve was 0.91. The PHQ-9 presented unidimensional structure with good scale reliability (α = 0.82). The PHQ-9 score presented the greatest correlations with SCL-90-R depression (r = 0.736) and WHOQOL-BREF mental HRQOL scales (r = -0.571), and all other correlations with disability and HRQOL were in the expected direction. Conclusion At a cutoff of 10, the PHQ-9 is an accurate, reliable, and valid measure for screening for MDD among Greek rheumatologic patients. Copyright © 2011 by the American College of Rheumatology.
    Original languageEnglish
    Pages (from-to)1313-1321
    Number of pages8
    JournalArthritis Care & Research
    Volume63
    Issue number9
    DOIs
    Publication statusPublished - Sept 2011

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