Validation of a Swahili version of the 9-item Patient Health Questionnaire (PHQ-9) among adults living with HIV compared to a community sample from Kilifi, Kenya

•Comparison of tool psychometrics between HIV-infected adults and community controls•Internal consistency and test-retest reliability of the adapted Swahili PHQ-9 is good•Swahili PHQ-9 is unidimensional overall, in HIV-infected adults and community sample•Swahili PHQ-9 is invariant across group (HIV-infected vs controls), sex and age-group•Swahili PHQ-9 exhibited good discriminant validity between the two participant groups Depression remains under-investigated in people living with HIV in sub-Saharan Africa due to paucity of adequately validated measures. This study aimed to validate an adapted version of the 9-item Patient Health Questionnaire (PHQ-9) among adults living with HIV compared to those from the community in Kilifi, Kenya. Analysis of data from 450 adults living with HIV and 337 adults from the community was conducted examining the reliability, factorial structure, measurement invariance and discriminant validity of interviewer-administered PHQ-9, Swahili version. Internal consistency of the Swahili PHQ-9 was good overall, in adults living with HIV and those from the community (Macdonald's omega > 0.80). The two-week test-retest reliability was acceptable among adults living with HIV (ICC = 0.64). A one-factor confirmatory factor analysis (CFA) model indicated the Swahili PHQ-9 was unidimensional in the overall sample, in adults living with HIV and those from the community. Multi-group CFA substantiated measurement invariance of this unidimensional scale across participant group (adults living with HIV vs. community), sex (females vs. males) and age category (young, middle-age and elderly adults). The Swahili PHQ-9 exhibited good discriminant validity between the two participant groups. No diagnostic interview for mental disorders was administered in the original studies limiting analysis of sensitivity and specificity of the Swahili PHQ-9. The Swahili PHQ-9 is a reliable and valid unidimensional scale. It appears a valuable tool for assessing depressive symptoms that can be generalized across different demographic groups, in primary HIV clinics and the general community within this and similar settings.