Educational inequalities in hypertension: complex patterns in intersections with gender and race in Brazil

Background: Hypertension is a major public health issue worldwide, but knowledge is scarce about its patterns and its relationship to multiple axes of social disadvantages in Latin American countries. This study describes the educational inequality in the prevalence of hypertension in Brazil, including a joint stratification by gender and race. Methods: We analyzed interview-based data and blood pressure measurements from 59,402 participants aged 18 years or older at the 2013 Brazilian National Health Survey (PNS). Sociodemographic characteristics analyzed were gender (male, female), racial self-identification (white, brown, black), age (5-years intervals), and educational attainment (pre-primary, primary, secondary, tertiary). Hypertension was defined as systolic blood pressure >= 140 mmHg and/or diastolic blood pressure >= 90 mmHg, and/ or self-reported use of antihypertensive medications in the last 2 weeks. We used logistic regression to evaluate the age-adjusted prevalences of hypertension (via marginal modeling), and pair-wise associations between education level and odds of hypertension. Further, the educational inequality in hypertension was summarized through the Relative Index of Inequality (RII) and the Slope Index of Inequality (SII). All analyses considered the appropriate sampling weights and intersections with gender, race, and education. Results: Age-adjusted prevalence of hypertension was 34.0 % and 30.8 % among men and women, respectively. Black and brown women had a higher prevalence than whites (34.5 % vs. 31.8 % vs. 29.5 %), whereas no racial differences were observed among men. White and brown, but not black women, showed graded inverse associations between hypertension and educational attainment; among men, non-statistically significant associations were observed in all racial strata. The RII and SII estimated inverse gradients among white (RII = 2.5, SII = 18.1 %) and brown women (RII = 2. 3, SII = 14.5 %), and homogeneous distributions of hypertension in educational subgroups among black women and among men. Conclusion: In this representative sample of Brazilian adults, the association between educational attainment and hypertension was influenced by gender and race -a topic still poorly understood. Our findings highlight the importance of assessing intersections of multiple sociodemographic characteristics in health inequalities research. The use of comprehensive measures of inequality, such as RII and SII, provide useful insights for monitoring health inequalities in an intersectional perspective.