Psychometric Validation of the Kazakh Version of the Patient Health Questionnaire-9 (PHQ-9)
Background: Depression is a major global health burden, requiring culturally appropriate assessment instruments, but no validated Kazakh-language version of the Patient Health Questionnaire-9 (PHQ-9) is available. This study aimed to translate, culturally adapt, and evaluate the psychometric properties of the Kazakh PHQ-9 in a community-based, non-clinical sample. Methods: This cross-sectional study included 503 Kazakh-speaking adults (mean age = 24.0 years, SD = 10.1; 51.3% women and 48.7% men) who completed the Kazakh PHQ-9 and Generalized Anxiety Disorder-7 (GAD-7) questionnaires. Internal consistency, structural validity, measurement invariance across genders, and convergent validity were assessed. Results: Internal consistency was excellent (Cronbach’s α = 0.91), and both one-factor and correlated two-factor models showed excellent fit (CFI = 0.998; TLI = 0.997–0.998; RMSEA = 0.046–0.048; SRMR = 0.050–0.052), with a slightly better fit for the latter. Measurement invariance across genders was supported, and PHQ-9 and GAD-7 scores were strongly correlated (r = 0.68, p < 0.001). Conclusions: The Kazakh PHQ-9 demonstrated excellent internal consistency and structural validity, measurement invariance across genders, and strong convergent validity in this non-clinical sample. These findings support its use for assessing depressive symptoms in Kazakh-speaking adults. Clinical validation is needed to establish diagnostic validity and screening performance.