The interaction between district-level development and individual-level socioeconomic gradients of cardiovascular disease risk factors in India: A cross-sectional study of 2.4 million adults.

BACKGROUND

Diabetes, hypertension, and obesity tend to be positively associated with socio-economic status in low- and middle-income countries (LMICs). It has been hypothesized that these positive socio-economic gradients will reverse as LMICs continue to undergo economic development. We use population-based cross-sectional data in India to examine how a district's economic development is associated with socio-economic differences in cardiovascular disease (CVD) risk factor prevalence between individuals.

METHODS

We separately analyzed two nationally representative household survey datasets - the NFHS-4 and the DLHS-4/AHS - that are representative at the district level in India. Diabetes was defined based on a capillary blood glucose measurement, hypertension on blood pressure measurements, obesity on measurements of height and weight, and current smoking on self-report. Five different measures of a district's economic development were used. We analyzed the data using district-level regressions (plotting the coefficient comparing high to low socio-economic status against district-level economic development) and multilevel modeling.

RESULTS

757,655 and 1,618,844 adults participated in the NFHS-4 and DLHS-4/AHS, respectively. Higher education and household wealth were associated with a higher probability of having diabetes, hypertension, and obesity, and a lower probability of being a current smoker. For diabetes, hypertension, and obesity, we found that a higher economic development of a district was associated with a less positive (or even negative) association between the CVD risk factor and education. For smoking, the association with education tended to become less negative as districts had a higher level of economic development. In general, these associations did not show clear trends when household wealth quintile was used as the measure of socio-economic status instead of education.

CONCLUSIONS

While this study provides some evidence for the "reversal hypothesis", large-scale longitudinal studies are needed to determine whether LMICs should expect a likely reversal of current positive socioeconomic gradients in diabetes, hypertension, and obesity as their countries continue to develop economically.