Methodologic Strategies for Quantifying Associations of Historical and Contemporary Mortgage Discrimination on Population Health Equity: A Systematic Review

Mortgage discrimination refers to the systematic withholding of home mortgages from minoritized groups. In recent years, there has been an increase in empirical research investigating associations of historical and contemporary mortgage discrimination on contemporary  outcomes. Investigators have used a variety of measurement methods and approaches, which may have implications for results and interpretation.

We conducted a systematic review of peer-reviewed literature that has quantified links between both historical and current mortgage discrimination with contemporary adverse environmental, social, and health outcomes. Our goals were to document the methodology used to measure and assign mortgage discrimination, to assess implications for results and interpretation, and to make recommendations for future work.

Following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines, literature searches were conducted in September 2022 using terms that combined concepts of mortgage discrimination, health, and neighborhood environment.

In total, 45 papers fit the eligibility criteria. In these, researchers investigated associations between mortgage discrimination and: (1) health outcomes (N = 28); (2) environmental and social exposures including heat, air pollution, greenspace, soil lead levels, and crime (N = 12); and (3) built environment features, including presence of retail alcohol, fast food, and tobacco stores (N = 5). Eleven included studies used Home Mortgage Discrimination Act (HMDA) data to identify racialized bias in mortgage discrimination or redlining, and 34 used Homeowner Loan Corporation (HOLC) maps. The construction and parametrization of mortgage discrimination or redlining and the spatial assignment of HOLC grades to contemporary addresses or neighborhoods varied substantially across studies.

Results from our review suggest the need for careful consideration of optimal methods to analyze mortgage discrimination such as HOLC spatial assignment or HMDA index parametrization, contemplation of covariates, and place-based knowledge of the study location.