Objective: The aim of this study was to determine the reliability and validity of a Chinese version of the Patient Health Questionnaire-9 item (PHQ-9) and its 2 subscales (1 item and 2 items) for the screening of major depressive disorder (MDD) among adolescents in Taiwan.
Methods: A total of 2257 adolescents were recruited from high schools in Taipei. The participants completed assessments including demographic information, the Chinese version of the PHQ-9, and the Rosenberg Self-Esteem Scale, and data on the number of physical illnesses and mental health service utilizations were recorded. Among them, 430 were retested using the PHQ-9 within 2 weeks. Child psychiatrists interviewed a subsample of the adolescents (n = 165) using the Kiddie-Schedule for Affective Disorder and Schizophrenia Epidemiological Version as the criterion standard.
Results: The PHQ-9 had good internal consistency (α = 0.84) and acceptable test-retest reliability (0.80). The participants with higher PHQ-9 scores were more likely to have MDD. Principal component factor analysis of the PHQ-9 yielded a 1-factor structure, which accounted for 45.3% of the variance. A PHQ-9 score ≥15 had a sensitivity of 0.72 and a specificity of 0.95 for recognizing MDD. The area under the receiver operating characteristic curve was 0.90. The screening accuracy of the 2 subscales was also satisfactory, with a Patient Health Questionnaire-2 item cutoff of ≥3 being 94.4% sensitive and 82.5% specific and a Patient Health Questionnaire-1 item cutoff of ≥2 being 61.1% sensitive and 87.7% specific.
Conclusions: The PHQ-9 and its 2 subscales appear to be reliable and valid for detecting MDD among ethnic Chinese adolescents in Taiwan.
Keywords: PHQ; adolescents; depression; questionnaire; reliability; validity.