Abstract MP019: Contributors to the Black-White Disparities in Incident Hypertension
Authors: Howard George , Cushman Mary , Moy Claudia S , Oparil Suzanne , Muntner Paul , Lackland Daniel T , Manly Jennifer , Flaherty Matthew , Judd Suzanne E , Wadley Virginia , Carson April , Long Leann , Howard Virginia J ,   for the REasons for Geographic And Racial Differences in Stroke (REGARDS) Investigators
Published: March 2022

Introduction:
While predictors of incident hypertension are well-studied, the factors explaining the black-white (B/W) disparity in the incidence of hypertension are unknown. Absent interactions, for a factor to contribute to this racial disparity, it must
both
: 1) have a large B/W difference in prevalence, and 2) be strongly associated with the risk of incident hypertension.

Methods:
We selected 20 established risk factors for hypertension to assess the degree to which they contribute to the black excess risk of incident hypertension. The B/W difference in hypertension risk factors was assessed by the standardized difference score (SDS: # standard errors difference in the B/W means) adjusting for age group. The impact of risk factors on incident hypertension was assessed by logistic regression adjusting for age group and baseline SBP. The mediation by each risk factor was calculated as the percent change in the regression coefficient for black race with additional adjustment for each risk factor.

Results:
Over a 10-year follow-up, 45% of 619 black and 36% of 2204 white men, and 52% of 994 black and 34% of 2409 white women, developed hypertension. The B/W difference in the mean southern diet score (assessed by a food frequency survey) was large for men (SDS =19.3) and women (SDS = 21.8). The diet score was also strongly associated with incident hypertension for men (OR = 1.17; 95% CI: 1.07-1.30) and women (OR = 1.18; 95% CI: 1.06-1.30). As such, the diet score was the most powerful mediator of the B/W difference in incident hypertension, accounting for 52% (95% CI: 19%-84%) of the black excess risk in men and 26% (95%CI: 10%-42%) in women. For women, BMI was the 2
nd
most powerful mediator, accounting for 17% (95% CI: 6% - 15%) of the excess black risk of hypertension (SDS = 9.5; OR = 1.04; 95% CI: 1.03-1.06); however, because BMI was similar in black and white men (SDS = 1.4) it did not significantly mediate the risk in men (p = 0.63). Low education was the 2
nd
most powerful mediator for men (14%: 95% CI: 3%-25%), but played a smaller role in women (4% mediation; 95% CI: 2% - 7%) because of a smaller B/W difference of the prevalence of low education in women (SDS = 1.4). The dietary sodium/potassium ratio (11%) was also a mediator in men; while in women (in decreasing order of mediation) low mobility (15%), low DASH diet score (11%), low income (10%), low neighborhood quality (8%), dietary sodium/potassium ratio (5%), low physical activity (5%) and low education (4%) also contributed to the excess black risk of incident hypertension. Other factors including exercise and discrimination did not significantly mediate the excess risk of hypertension in blacks.

Conclusions:
This report provides insights to the contributors of the higher incidence of hypertension in blacks, with a high consumption of southern foods being the most powerful contributor to black disparity in incidence of hypertension for both men and women.