Psychometric Properties of the Persian Version of Patient Health Questionnaire-9

 The Patient Health Questionnaire-9 (PHQ-9) is one of the most commonly used measures for screening, diagnosing and monitoring of depression. So far, four studies have examined some of the psychometric properties of Persian version of PHQ-9 in physical and psychiatric patients; however, some aspects of its psychometrics have not yet been adequately evaluated in the student population. Therefore, this study aims to examine more psychometric properties of the Persian version of PHQ-9 in the student population.

 In this descriptive study, 463 students of Guilan University of Medical Sciences in the academic year 2018-19 participated who were selected using a convenience sampling method. The reliability of the Persian PHQ-9 was assessed using internal consistency and test-retest reliability for a 2-week interval. Its construct validity was evaluated by exploratory and confirmatory factor analyses. To evaluate its convergent validity, the second version of the Beck Depression Inventory (BDI-II), the depression subscale of the 21-item Depression Anxiety Depression Inventory (DASS-21), the neuroticism subscale of NEO Five Factor Inventory (NEO-FFI) and the negative affect subscale of the Positive Affect and Negative Affect Scale (PANAS) were used. The openness subscale of NEO-FFI and the positive affect subscale of PANAS were also used to assess its discriminant validity.

 Cronbach’s alpha coefficient of 0.856 and intraclass correlation coefficient of 0.869 indicated high internal consistency and test-retest reliability of the Persian PHQ-9, respectively. Exploratory factor analysis results showed a one-factor structure, accounting for 47.59% of the total variance. Confirmatory factor analysis results showed that all questions were related to one factor. Positive correlation of the Persian PHQ-9 score with BDI-II (r= 0.769), the neuroticism subscale of NEO-FFI (r= 0.508), the depression subscale of DASS-21 (r= 0.647) and the negative affect subscale of PANAS (r= 0.430) indicated an acceptable convergent validity, while its negative correlation with the positive affect subscale PANAS (r= -0.444) indicated its acceptable discriminant validity; however, its score had no significant relationship with the openness subscale of NEO indicates NEO-FFI (r= 0.116).

 The Persian PHQ-9 can be used in clinical and research fields to screen, diagnose, and monitor clinical and/or subclinical depression in the Iranian student population.