Validation of the Patient Health Questionnaire-4 (PHQ-4) to screen for depression and anxiety in the Greek general population

The Patient Health Questionnaire-4 (PHQ-4) is an ultra-brief self-report screening scale for depression and anxiety with promising psychometric properties; however, its reliability and validity have not been investigated in Greece yet. The objective of the current study was to investigate the reliability and validity of the PHQ-4 and to establish a cut-off score to identify depression and anxiety in the Greek general population.The reliability of the PHQ-4 was assessed using a random sample of 204 students from Athens, Greece. The internal consistency (Cronbach's α) was evaluated whereas the test-retest reliability was measured over a one-week period with intra-class correlation (ICC). The scale's validity was assessed in a cross-sectional study of 591 adults living in Greece using confirmatory factor analysis (CFA). Cut-offs were determined using the Mini International Neuropsychiatric Interview (MINI) as the gold standard.Cronbach's α of the PHQ-4 was 0.80 and the overall ICC 0.96. CFA yielded a two-factor model, structurally invariant by age and gender. A GAD-2 score of 2 was the optimal cut-off point to detect any anxiety disorder (sensitivity = 0.82, specificity = 0.75) and 3 to detect generalized anxiety disorder (sensitivity = 0.77, specificity = 0.82). As for PHQ-2, a score of 2 was the optimal cut-off point to detect any depressive disorder (sensitivity = 0.87, specificity = 0.85) and 3 to detect major depressive disorder (sensitivity = 0.77, specificity = 0.94).The PHQ-4 is a reliable and valid screening scale for depression and anxiety in the Greek general population.