Analyzing the psychometric properties of the PHQ-9 using item response theory in a Chinese adolescent population

Ann Gen Psychiatry. 2024 Jan 23;23(1):7. doi: 10.1186/s12991-024-00492-3.

Abstract

Background: People are more likely to fall victim to depression during adolescence since it is a period of rapid biopsychosocial transformation. Despite this, most depression research has concentrated on clinical issues, and evaluating depressive symptoms in teenagers is not as widespread. This study used item response theory (IRT) to examine the psychometric properties of the Patient Health Report scale (PHQ-9) in Chinese adolescents. Meanwhile, item function difference tests were used to check whether there were differences in depression symptoms in this group based on education and gender.

Methods: In this research, the PHQ-9 was employed as a measurement tool, and 5958 valid data points were obtained from 12 secondary schools in China (Mage = 13.484; SDage = 1.627; range 11-19 years; 52.17% boys).

Results: IRT shows that all items of the PHQ-9 satisfy monotonicity, unidimensionality and local independence and that they have good psychometric properties. Furthermore, DIF analysis revealed gender and educational disparities in adolescent depressive symptoms.

Conclusion: The study indicates that the PHQ-9 possesses favourable psychometric properties for use in Chinese adolescents. As a result, it serves as a valuable tool for effectively screening depressive symptoms in adolescents. It provides a foundation for prioritizing the development of secondary school students' physical and mental health.

Keywords: Differential item functioning; Graded response model; Item response theory; PHQ-9; Psychometric analysis.