Standardization of the Korean Version of the Patient Health Questionnaire-4 (PHQ-4).

Objective: The Patient Health Questionnaire-4 (PHQ-4) has been used for screening owing to ease of use and brevity. In this study, we developed the Korean version of the PHQ-4 and tested its validity.
Methods: One hundred sixteen new adult outpatients at the Department of Psychiatry of the Korea University Ansan Hospital participated in the study. We simultaneously administered other depression/anxiety scales: the Hamilton Rating Scale for Depression, the Hamilton Anxiety Scale, the Beck Depression Inventory, and the Beck Anxiety Inventory.
Results: The mean PHQ-4 score was 6.52 (standard deviation = 3.45). Cronbach's α was 0.792, and the intraclass correlation coefficient of test and 2-week interval retest was 0.827 ( p < 0.01). The Pearson correlation coefficients between the PHQ-4 total score and other depression/anxiety scales were all over 0.6. Confirmatory factorial analysis showed acceptable convergent validity and reliability but questionable discriminant validity for some model fit values.
Conclusion: The Korean version of the PHQ-4 has sufficient internal consistency, test-retest reliability, and construct validity, but its two-factor structure showed incompleteness. However, we suggest that it should be used as a brief screening measure for common psychiatric distress that warrants further detailed assessment, but not to separately assess the severity of depression and anxiety symptoms.