A systematic review of historic neighborhood redlining and contemporary health outcomes.

Objectives: Historic redlining grades that were assigned to US neighborhoods based largely on minority race or ethnicity by the Home Owners Loan Corporation (HOLC) during the 1930s have been linked with adverse health outcomes among neighborhood residents. This review aimed to summarize the quantitative evidence, so we could determine if any findings are replicated and otherwise identify research gaps.

Study design: Systematic review.

Methods: We conducted a systematic review by searching the PubMed® MEDLINE database for observational studies that reported on health outcomes among people who resided in neighborhoods that were assigned HOLC grades. We assessed quality by allocating points based on whether studies reported the sample size or count of people affected by outcomes (yes = 1 point, no = 2 points), and whether unadjusted magnitudes of association were reported alongside adjusted estimates (yes = 1 point, no = 2 points). The sum score was used to classify each study as high (2 points), average (3 points) or low quality (4 points).

Results: Among the 89 articles identified, 32 met inclusion criteria; 15 were deemed high-quality. The most frequently studied health conditions in order of descending frequency were: i) injury or violence (n = 8), ii) cancer (n = 7), iii) cardiometabolic (n = 6), iv) perinatal (n = 5), v) asthma (n = 2).

Conclusion: People who lived in areas with less desirable HOLC grades tended to suffer higher than expected rates of injury or violence, asthma, adverse pregnancy outcomes, and some cardiometabolic disorders; associations with cancer were mostly null. Methodological differences limited opportunities for direct comparison across studies, and there was significant heterogeneity among the few estimates that were generally comparable. While robust data are lacking, the limited existing evidence supports a possible association between historically redlined areas and heightened risk of adverse health outcomes. Why this association may exist remains unknown.