Association of socioeconomic inequality in cardiovascular disease risk with economic development across 57 low- and middle-income countries: Cross-sectional analysis of nationally representative individual-level data.

Background: According to epidemiological transition theory, cardiovascular disease (CVD) risk shifts down the socioeconomic distribution with economic development.

Methods: We tested this hypothesis using nationally representative data on 88,559 individuals aged 40-80 years from 57 low- and middle-income countries (LMICs). We used measured risk factors to estimate the 10-year probability of a CVD event (CVD risk) and proxied socioeconomic status (SES) by years of education. We used a concentration index to measure socioeconomic inequality in CVD risk and decomposed it into risk factor contributions. We estimated associations CVD risk and inequality in that risk with gross national income (GNI) per capita (pc).

Results: We estimated that a 1% higher GNI pc was associated with higher mean CVD risk of 0.0265 percentage points (pp) (95% CI: 0.0169-0.0361) among females and 0.0150 pp (0.0082-0.0219) among males. All risk factors, except systolic blood pressure (SBP) and smoking among females, were positively associated with GNI pc. In most countries, lower SES was associated with higher CVD risk. Age, SBP, diabetes (females only) and smoking (males particularly) contributed most to this inequality, while inequality in total cholesterol was mostly in the opposite direction. Lower SES individuals tended to have relatively higher CVD risk at higher GNI pc, particularly among females. This was due to differences in the distributions of SBP and, for females, age and diabetes.

Conclusions: Economic development was associated with higher and more unequal CVD risk, which may warrant shifting targeting of CVD primary prevention to socially disadvantaged groups.