The prevalence of cardiovascular disease risk factors among adults living in extreme poverty: a cross-sectional analysis of 105 nationally representative surveys with 33 million participants

Background: Historically, the international development community has often held the view that those living in extreme poverty (at less than $1.90/day) are likely to have a low prevalence of cardiovascular disease (CVD) risk factors due to calorie scarcity, a largely plant-based diet, and physical labor. Evidence on CVD risk factor prevalence among adults living below the World Bank's international line for extreme poverty globally is sparse because studies have used measures of socioeconomic status that are not comparable across study populations and countries. For adults living in extreme poverty, this study aimed to determine i) the prevalence of each of five key CVD risk factors, ii) how the prevalence of these CVD risk factors varies across and within countries, and iii) the level of treatment coverage with statin, antihypertensive, and diabetes therapy. Methods: We pooled individual-level data from 105 nationally representative household surveys with physical measurements of hypertension, diabetes, overweight, obesity, and dyslipidemia, as well as self-reported smoking status, from 78 countries that represent 85% of people living in extreme poverty globally. Those living in extreme poverty were defined by ordering participants according to a continuous household wealth index or household income value, and then applying World Bank estimates on the proportion of each country's population that is living in extreme poverty. We used modified Poisson regression models to examine how CVD risk factor prevalence among those in extreme poverty varied by age, sex, educational attainment, and rural versus urban residency. We also calculated the proportion of participants with diabetes or hypertension who self-reported the use of blood pressure- or blood glucose-lowering medication, respectively; the proportion with hypertension who achieved blood pressure control; and the proportion recommended for statin use according to WHO guidelines who reported taking a statin. Results: Of 32,695,579 participants, 7,922,289 were living in extreme poverty (<$1.90 per day), 15,986,099 on less than $3.20/day, and 23,466,879 on less than $5.50/day. Among those living in extreme poverty (<$1.90 per day), the age-standardized prevalence was 17.5% (95% CI: 16.7% - 18.3%) for hypertension, 4.0% (95% CI: 3.6% - 4.5%) for diabetes, 10.6% (95% CI: 9.0% - 12.3%) for current smoking, 3.1% (95% CI: 2.8% - 3.3%) for obesity, and 1.4% (95% CI: 0.9% - 1.9%) for dyslipidemia. In most countries in our analysis, the prevalence of these risk factors among those living in extreme poverty was not notably lower than in the total population. Hypertension treatment and control, diabetes treatment, and statin use were low across all poverty levels in low-income countries, while in lower and upper middle-income countries individuals living at more extreme levels of poverty had a lower probability of reporting the use of these medications and achieving hypertension control. Conclusions: We found a high prevalence of CVD risk factors among adults living below the World Bank's international line for extreme poverty, along with low statin use and low treatment rates for diabetes and hypertension. Our detailed analysis and comparison across poverty levels could inform equity discussions for resource allocation and the design of effective interventions.