Screening for depression with the Patient Health Questionnaire-2 (PHQ-2) among the general population in Hong Kong

Background: This study investigates the psychometric properties of the Patient Health Questionnaire-2 (PHQ-2) in the general population of Hong Kong. Methods: Random sampling was used to recruit 6028 participants aged 15 years or over. Among them, 203 were surveyed twice within a two-week period. Participants completed the Chinese version of the PHQ-9 (including 2 items of the PHQ-2), the Chinese Health Questionnaire, the Happiness Scale, the SF-12, and questions about diagnosis and health service utilization. Internal consistency, test-retest reliability, construct and discriminant validity of the PHQ-2 were assessed. Results: Cronbach's α was 0.76. The test-retest reliability over two weeks calculated by intraclass correlation was 0.70. Spearman correlation results showed that the PHQ-2 score was associated with the remaining seven items of the PHQ-9 (r = 0.53), the Chinese Health Questionnaire (r = 0.37), and the Happiness scale (r = - 0.32). As expected, the strength of the correlation between the PHQ-2 and the SF-12 Physical Component Summary was lower (r = - 0.29) than that with the SF-12 Mental Component Summary (r = - 0.50). Participants with higher PHQ-2 scores more frequently reported having received a depression diagnosis made by a doctor, having chronic illness, using medicine, and utilizing health services. Using the cutoff point ≥ 3, 4.2% of participants screened positive for Major Depressive Disorder. Limitations: We did not use diagnostic interviews or other depression measures to test the PHQ-2's relative performance in screening for depression. Conclusions: This study provides evidence for the PHQ-2 as a reliable and valid screening tool for depressive symptoms among a randomly recruited community sample in Hong Kong.