Abstract Body: Background: Many studies link adverse neighborhood context with racial myocardial infarction (MI) disparities. Research may reflect strong publication bias for chance associations in main or race-specific effects.
Hypothesis: We theorized that associations would vary in direction as well as magnitude across two national cohorts due to differences in sample composition, outcome ascertainment, and parent study sampling schema.
Methods: We compared results from the REasons for Geographic and Racial Differences in Stroke (REGARDS, n=25,143, aged ≥ 45 years, 42% Non-Hispanic (NH) Black; 2003-2018) study to the Health and Retirement Study (HRS, n=14,1941, aged > 50 years, 13% Non-Hispanic Black; 2004-2018). We estimated Cox models predicting MI for 51 American Community Survey (ACS) census tract (CT) variables and evaluated consistency of main and racially-stratified estimates between cohorts.
Results: Follow-up in REGARDS (median=11.5 years; IQR: 6.5, 13.6) was similar to HRS (median=13.1; IQR: 8.3, 14.1), as was cumulative MI incidence (6.2% and 7.1%). The proportions of NH White and NH Black adults were at least moderately collinear in both samples (r among White REGARDS participants-0.95, among Black REGARDS participants=-0.94, among White HRS participants= -0.63, and among Black HRS participants-=0.82). Sixteen ACS variables had estimated effects with incident MI that differed by at least 0.05 between cohorts. The estimated effect of the percentage of adults with less than a high school diploma was stronger in REGARDS (HR per SD: 1.10; 95% CI: 1.04, 1.17) than HRS (HR per SD: 1.04; 95% CI: 0.94, 1.15); the estimated effect of the percentage of residents in poverty was attenuated in REGARDS (HR per SD: 1.05; 95% 1.00, 1.11) compared to HRS (HR per SD: 1.17; 95% 1.07, 1.27). Differences in the estimated effects for 12 ACS variables across racial strata (p<0.05) identified in REGARDS were not corroborated in HRS.
Conclusions: Neighborhood socioeconomic associations with MI across two national studies broadly replicated in direction but differed in magnitude. Inadequate statistical power and sample differences at the level of participant as well as of neighborhood likely contributed to inconsistent estimated effects by race.