Factor IX and incident hypertension in Black and White adults: the REasons for Geographic and Racial Differences in Stroke cohort.

BACKGROUND

Hypertension is a cardiovascular disease risk factor disproportionately affecting Black adults. Certain biomarkers of thrombosis and inflammation are associated with a greater risk of hypertension. Factor IX is a marker of thrombosis; Black adults have higher levels than others. Whether factor IX correlates with incident hypertension risk or explains some of the disproportionate burden faced by Black adults, is not known.

METHODS

REasons for Geographic and Racial Differences in Stroke (REGARDS) recruited 30 239 Black and White adults from the contiguous US in 2003-2007 (Visit 1) and had repeat assessment in 2013-2016 (Visit 2). Factor IX was measured in Visit 1 samples in a sex-race stratified sample of 4400 participants that attended both visits. Modified Poisson regression estimated adjusted risk ratios (RR) for incident hypertension at Visit 2 by factor IX tertiles. Inverse odds ratio weighting estimated the proportion of the excess burden of incident hypertension in Black adults due to factor IX levels.

RESULTS

Among 1824 participants (55% female and 24% Black race), 36% developed hypertension. The fully adjusted RR for the third vs. first tertile was 1.21; 95% confidence interval (CI) 1.03-1.43, and there was a significant linear trend across tertiles ( P  < 0.001). Factor IX did not mediate excess hypertension risk among Black adults in adjusted models.

CONCLUSIONS

In this prospective study of Black and White adults without prevalent hypertension, higher factor IX was associated with a greater risk of incident hypertension. This risk may relate to adverse thromboinflammation among persons in the 2nd and 3rd tertiles of factor IX.