Cardiovascular diseases in rural South Asia: the story of one billion people

Abstract

The Global Burden of Disease Study reported that from 1990 to 2019, cardiovascular diseases (CVDs) emerged as a leading cause of disabilityadjusted lifeyears (DALYs) in South Asians of both genders (15.2% of total DALYs in men and 11.9% in women). South Asia is largely rural with a population of approximately 1.2 billion people and projected to remain rural through to 2050, with a similar number of people. In 2014, the multicountry Prospective Urban Rural Epidemiology (PURE) cohort study found that rural South Asians experienced higher incidence rates for CVD mortality and morbidity (7.2 per 1000 personyears) compared with their urban counterparts (5.6 per 1000 personyears), from myocardial infarction, heart failure and stroke. This is despite rural South Asians having a comparatively better CVD risk profile, an INTERHEART risk score of 7.6 compared with 9.1. Over the past 30 years (1985– 2017), the increase in agestandardised mean body mass index (BMI) in the adult rural population has outpaced urban counterparts. It follows that the urban– rural BMI difference seen in both genders, has reduced by roughly onehalf over the same period, from an original difference of ~3.25 kg/m. To address the increasing CVD burden in rural South Asia, particularly because of the wellestablished nexus between poverty and noncommunicable diseases, a systematic approach is needed including lifecourse research on risk factors and determinants, and evidencebased policy. The poorest and most vulnerable one billion people globally, reside in rural South Asia and subSaharan Africa and experience onefifth of their total DALYs from ischaemic heart disease, stroke and diabetes in individuals above 40 years of age. Additional families are at increased risk of being pushed into poverty by catastrophic health expenditure from accessing healthcare, and loss of income from a poor health status. To date, most CVD research in South Asia has focused on urbanisation, addressing South Asians living in urban areas, or in developed countries. We have limited knowledge about CVD mechanisms across the lifecourse in rural South Asia, including individual risk factors and their determinants. For instance, research suggests that rural environments are increasingly obesogenic with unhealthy food, nonmanual occupations, mechanisation of transport, agriculture and water supply to households, and increasing screen time prevalent. It has also been postulated that rural populations have preexisting low metabolic capacity due to transgenerational undernourishment and communicable diseases. Finally, poor healthcare access has been associated with lower rates of detection and management of metabolic risk factors, including dyslipidaemia, hypertension and diabetes. With limited ruralfocused research, it follows that current CVD policies lack a ruralspecific, evidencebased and comprehensive approach. For instance, despite tobacco use being higher in rural compared with urban settings, the current WHO Framework Convention on Tobacco Control does not adequately address the high prevalence of informal noncigarette tobacco products in rural settings. Similarly, CVD healthcare policy is too simplistic and centred around health awareness, screening and referral for tertiary medical or surgical interventions. Incremental CVD interventions should be provided for the entire disease course and with an overall aim of minimising DALYs and associated poverty at a population level. Further, the policy focus needs to change from diseased individuals to healthy environments, designed to mitigate CVD risk over the lifecourse. This is especially important as the rural environment is rapidly changing due to globalisation, economic development, commercialisation of food systems, technological advances and government policy (or lack thereof). 8 For instance, rural airquality is affected by proximity to urban areas and industries, plus local sources like burning of crop residue or biomass. However, the current policy does not include rural airquality monitoring and management. As rural and urban settings share a common airshed, an effective policy requires airquality management to occur concurrently in both settings. Finally, rural South Asia provides a unique opportunity to understand the mechanisms of increasing CVDs in South Asians who experience a higher risk compared with other ethnicities. Rapidly changing built environment and lifestyles, 8 including physical activity and nutrition, provides a prime setting of a natural experiment to assess association of these factors with early increases in CVD disease burden. This environmental transition is increasingly being measured on a continuum, like nighttime light intensity, moving beyond the outmoded urban–rural dichotomy. This knowledge could help inform interventions to mitigate CVD risk in similar rapidly developing lowmiddleincome countries, and South Asians living in developed settings. In summary, remaining true to the international pledge of ‘leaving no one behind’, CVD must be recognised as an urgent health priority in rural South Asia, and addressed coherently to prevent related death, disability and poverty.