Housing Instability as a Barrier to HIV Viral Suppression: Evidence from a U.S. Systematic Review and Meta-analysis

Housing instability and homelessness remain pervasive structural determinants of poor HIV outcomes in the United States. People living with HIV (PLWH) who experience homelessness face intersecting barriers, including stigma, behavioral comorbidities, and fragmented care systems, that undermine antiretroviral therapy adherence and viral suppression (VS). To quantify the impact of homelessness on viral suppression, we conducted a systematic review and meta-analysis of U.S.-based studies published from 2014 to 2024. Following PRISMA 2020 guidelines, PubMed, SCOPUS, and Web of Science were searched using controlled vocabulary and keywords related to HIV, viral suppression, and homelessness. Eligible studies included quantitative and/or qualitative analyses of PLWH reporting associations between housing instability or homelessness and VS outcomes. Study suitability was assessed using an adapted GRACE checklist, and random-effects meta-analysis was conducted in STATA v19 to pool adjusted odds ratios (aORs), with heterogeneity assessed via Q and I2 statistics. Of 603 identified studies, 43 met inclusion criteria and 21 contributed to the meta-analysis (total n = 46,291). Individuals experiencing homelessness had significantly lower odds of VS compared with housed counterparts (pooled OR = 0.38, 95% CI 0.33–0.45), with moderate to high heterogeneity (I2 = 74.2%) but consistent directionality across definitions of housing instability and analytic adjustments. No evidence of publication bias was detected (Egger’s p = 0.125). Thematic synthesis identified five primary pathways linking homelessness to reduced VS: disrupted ART adherence and retention; psychosocial stressors such as stigma and depression; syndemic interactions with substance use and mental illness; stress-related immune dysregulation; and broader structural inequities including poverty, criminalization, and neighborhood disadvantage. Overall, findings demonstrate a robust and persistent association between homelessness and lower odds of HIV viral suppression, underscoring housing as a fundamental social determinant of health. Integrated, low-barrier housing interventions paired with behavioral health and case management services show the greatest promise for improving viral suppression and advancing equity. Addressing housing instability of any severity is essential to achieving the goals of the Ending the HIV Epidemic initiative and sustaining Undetectable = Untransmittable (U = U) outcomes.