Significant variation in blood pressure control and certain cardiovascular outcomes were observed according to the socioeconomic context in which participants received clinical care, according to a study published in the Journal of the American Heart Association.
The investigators sought to examine whether outcomes from antihypertensive therapy, including the ability to control blood pressure and adverse cardiovascular events, vary due to the effect of socioeconomic context in the setting of randomized controlled trials.
The investigators analyzed data from 27,862 participants in the Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial (ALLHAT). To study the effect of the socioeconomic context, the investigators stratified the clinical sites where participants received care by income quintiles using county-level median income as a proxy. ALLHAT participants in the lowest- (1) and highest-income (5) quintiles were then compared for baseline demographic factors, blood pressure control, and cardiovascular outcomes.
Compared with quintile 5, participants from quintile 1 sites were more likely to be living in the South (91%), be women, be black or Hispanic, have attained lower levels of education, and have fewer cardiovascular risk factors. After adjusting for baseline demographic and clinical characteristics, in which participants from both quintiles had similar baseline blood pressure, participants in quintile 1 were significantly less likely to achieve blood pressure control (odds ratio 0.48; 95% CI, 0.37-0.63). In adjusted analyses, participants in quintile 1 experienced greater all-cause mortality (hazard ratio [HR] 1.25; 95% CI, 1.10-1.41), heart failure hospitalizations/mortality (HR 1.26; 95% CI, 1.03-1.55), and end-stage renal disease (HR 1.86; 95% CI, 1.26-2.73) compared with participants in quintile 5; however, participants in quintile 1 reported fewer hospitalizations for angina (HR 0.70; 95% CI, 0.59-0.83) and coronary revascularizations (HR 0.71; 95% CI, 0.57-0.89). No differences were observed between quintiles for rates of new-onset heart failure, peripheral arterial disease, or stroke.
Limitations of the study included potential disparities between the clinical site and the participant’s county of residence, and that counties differed in size and may have been composed of several socioeconomic contexts. The analysis did not adjust for individual facilities, and the investigators were unable to account for the correlation of outcomes within an area. Also, area income may not be the perfect measure for social risk factors that affect health outcomes. Finally, ALLHAT data are nearly 20 years old and did not measure medication adherence; disparities in hypertension outcomes may have been addressed in the meantime.
The researchers concluded that ALLHAT participants in the lowest-income study sites experienced worse blood pressure control and poorer cardiovascular outcomes despite standardized treatment protocols and having similar baseline blood pressure as participants in the highest income areas. The investigators suggest that measuring and addressing the socioeconomic context is important to reduce potential disparities in care.
Shahu A, Herrin J, Dhruva SS, et al. Disparities in socioeconomic context and association with blood pressure control and cardiovascular outcomes in ALLHAT [published online July 31, 2019]. J Am Heart Assoc. doi: 10.1161/JAHA.119.012277