Validation of Patient Health Questionnaire for depression screening among primary care patients in Taiwan.

Purpose: The aim of this study was to determine the reliability and validity of a Chinese version of the Patient Health Questionnaire (PHQ-9) for the purpose of screening major depressive disorder (MDD) among primary care patients in Taiwan.

Method: A total of 1954 primary care patients completed the PHQ-9. Patients (n = 1532) were interviewed using the Schedule for Clinical Assessments in Neuropsychiatry and 17-item of Hamilton Rating Scale. Subsample cases were retested within 2 weeks.

Results: The PHQ-9 had a good internal consistency (α = .80) and test-retest reliability (intraclass correlation coefficient = 0.87). A principal component factor analysis yielded 1-factor structure, which accounted for a total of 42.0% of the variance. The PHQ-9 was significantly correlated with the external validators such as the 17-item of Hamilton Rating Scale and the Short Form of the Quality of Life Enjoyment and Satisfaction Questionnaire (P < .001). Using the Schedule for Clinical Assessments in Neuropsychiatry interview as the criterion standard, a PHQ-9 score of 10 or higher had a sensitivity of 0.86 and a specificity of 0.94 for recognizing MDD. The screening accuracy of the 2 items version, PHQ-2, was also satisfactory (scores ≥ 2: sensitivity 0.88; specificity 0.82). The single-question screen, PHQ-1 (depressed mood), was 78% sensitive and 93% specific for detecting MDD (score ≥ 2).

Conclusion: The PHQ-9 and its 2 subscales, PHQ-2 and PHQ-1, seem reliable and valid for detecting MDD among Chinese primary care patients.