Social Determinants of Health and Incident Apparent Treatment-Resistant Hypertension Among White and Black US Adults: The REGARDS Study

Abstract

Background: We examined the association of multilevel social determinants of health with incident apparent treatment-resistant hypertension (aTRH).

Methods and results: We analyzed data from 2774 White and 2257 Black US adults from the REGARDS (Reasons for Geographic and Racial Differences in Stroke) study taking antihypertensive medication without aTRH at baseline to estimate the association of social determinants of health with incident aTRH. Selection of social determinants of health was guided by the Healthy People 2030 domains of education, economic stability, social context, neighborhood environment, and health care access. Blood pressure (BP) was measured during study visits, and antihypertensive medication classes were identified through a pill bottle review. Incident aTRH was defined as (1) systolic BP ≥140 mm Hg or diastolic BP ≥90 mm Hg, or systolic BP ≥130 mm Hg or diastolic BP ≥80 mm Hg for those with diabetes or chronic kidney disease while taking ≥3 classes of antihypertensive medication or (2) taking ≥4 classes of antihypertensive medication regardless of BP level, at the follow-up visit. Over a median 9.5 years of follow-up, 15.9% of White and 24.0% of Black adults developed aTRH. A percent of the excess aTRH risk among Black versus White adults was mediated by low education (14.2%), low income (16.0%), not seeing a friend or relative in the past month (8.1%), not having someone to care for them if ill or disabled (7.6%), lack of health insurance (10.6%), living in a disadvantaged neighborhood (18.0%), and living in states with poor public health infrastructure (6.0%).

Conclusions: Part of the association between race and incident aTRH risk was mediated by social determinants of health.

Keywords: education; hypertension; income; neighborhood; social determinants of health; treatment‐resistant hypertension.

Figure 1. Flowchart showing the number of REGARDS study participants included in the current analysis.

*Excluded 6209 REGARDS study participants who did not attend the follow‐up visit; 126 participants without complete information on SBP, DBP, and antihypertensive medication use at a follow‐up visit; and 92 participants with undetermined BP control status at the follow‐up visit due to missing information on diabetes or chronic kidney disease. aTRH indicates apparent treatment‐resistant hypertension; DBP, diastolic blood pressure; REGARDS, Reasons for Geographic and Racial Differences in Stroke; and SBP, systolic blood pressure.

Figure 2. Proportion of REGARDS study participants developing aTRH by number of adverse social determinants of health, overall (A) and for White and Black participants separately (B).

Adverse social determinants of health included having less than a high school education, annual household income <$35 000, not having someone to care for them if ill or disabled, residing in a disadvantaged neighborhood (neighborhood socioeconomic score in the first quartile), living in a state with low public health infrastructure, and lack of health insurance. aTRH was defined as systolic blood pressure ≥140 mm Hg or diastolic blood pressure ≥90 mm Hg (systolic blood pressure ≥130 mm Hg or diastolic blood pressure ≥80 mm Hg for those with diabetes or chronic kidney disease) while taking ≥3 classes of antihypertensive medication or taking ≥4 classes regardless of blood pressure level. aTRH indicates apparent treatment‐resistant hypertension; REGARDS, Reasons for Geographic and Racial Differences in Stroke; and SDOH, social determinants of health.

Figure 3. Percentage of the excess risk of aTRH experienced among Black compared with White REGARDS participants explained by SDOH.

aTRH was defined as systolic blood pressure ≥140 mm Hg or diastolic blood pressure ≥90 mm Hg (systolic blood pressure ≥130 mm Hg or diastolic blood pressure ≥80 mm Hg for those with diabetes or chronic kidney disease) while taking ≥3 classes of antihypertensive medication, or taking ≥4 classes regardless of blood pressure level. Total effect hazard ratio (1.59 [95% CI, 1.39–1.82]), was estimated as the β coefficients of the association of Black vs White race with incident aTRH in an interval‐censored regression model adjusting for age and sex. Natural direct effect was estimated as the β coefficients of the association of Black vs White race with incident aTRH in an interval‐censored regression model adjusting for age and sex, with weights applied. Weights were estimated as the predicted probability of the exposure (Black race) on the mediator (SDOH) adjusting for age and sex in a logistic regression model. Natural indirect effect was estimated by subtracting the total effect from the direct effect. Proportion mediated was estimated by the ratio of the indirect effect by the total effect. The 95% CIs for the total, direct, indirect effects, and proportion mediated were calculated using the bias correction and acceleration method from 500 bootstrapped samples. All SDOH are from a weights model that included all SDOH modeled simultaneously. aTRH indicates apparent treatment‐resistant hypertension; REGARDS, Reasons for Geographic and Racial Differences in Stroke; and SDOH, social determinants of health.