Abstract
IMPORTANCE: Housing insecurity-that is, difficulty with housing affordability and stability-is prevalent and results in increased risk for both homelessness and poor health. However, whether interventions that prevent housing insecurity upstream of homelessness improve health remains uncertain. OBJECTIVE: To review evidence characterizing associations of primary prevention strategies for housing insecurity with adult physical health, mental health, health-related behaviors, health care use, and health care access. EVIDENCE REVIEW: Pairs of independent reviewers systematically searched PubMed, Web of Science, EconLit, and the Social Interventions Research and Evaluation Network for quantitative studies published from 2005 to 2021 that evaluated interventions intended to directly improve housing affordability and/or stability either by supporting at-risk households (targeted primary prevention) or by enhancing community-level housing supply and affordability in partnership with the health sector (structural primary prevention). Risk of bias was appraised using validated tools, and the evidence was synthesized using modified Grading of Recommendations Assessment, Development, and Evaluation criteria. FINDINGS: A total of 26 articles describing 3 randomized trials and 20 observational studies (16 longitudinal designs and 4 cross-sectional quasi-waiting list control designs) were included. Existing interventions have focused primarily on mitigating housing insecurity for the most vulnerable individuals rather than preventing housing insecurity outright. Moderate-certainty evidence was found that eviction moratoriums were associated with reduced COVID-19 cases and deaths. Certainty of evidence was low or very low for health associations of other targeted primary prevention interventions, including emergency rent assistance, legal assistance with waiting list priority for public housing, long-term rent subsidies, and homeownership assistance. No studies evaluated health system-partnered structural primary prevention strategies. CONCLUSIONS AND RELEVANCE: This systematic review found mixed and mostly low-certainty evidence that interventions that promote housing affordability and stability were associated with improved adult health outcomes. Existing interventions may need to be paired with other efforts to address the structural determinants of health. As health care systems and insurers respond to increasing opportunities to invest in housing as a determinant of health, further research is needed to clarify where along the housing insecurity pathway interventions should focus for the most effective and equitable health impact.