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

Background: 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. Methods: 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. Results: 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. Limitations: No diagnostic interview for mental disorders was administered in the original studies limiting analysis of sensitivity and specificity of the Swahili PHQ-9. Conclusion: 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.