Socioeconomic status and risk of cardiovascular disease in 20 low-income, middle-income, and high-income countries: the Prospective Urban Rural Epidemiologic (PURE) study
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Date
2019Author
Rosengren, Annika
Kruger, Iolanthé M.
Smyth, Andrew
Rangarajan, Sumathy
Ramasundarahettige, Chinthanie
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Background Socioeconomic status is associated with differences in risk factors for cardiovascular disease incidence
and outcomes, including mortality. However, it is unclear whether the associations between cardiovascular disease
and common measures of socioeconomic status—wealth and education—differ among high-income, middle-income,
and low-income countries, and, if so, why these differences exist. We explored the association between education and
household wealth and cardiovascular disease and mortality to assess which marker is the stronger predictor of
outcomes, and examined whether any differences in cardiovascular disease by socioeconomic status parallel
differences in risk factor levels or differences in management.
Methods In this large-scale prospective cohort study, we recruited adults aged between 35 years and 70 years from
367 urban and 302 rural communities in 20 countries. We collected data on families and households in
two questionnaires, and data on cardiovascular risk factors in a third questionnaire, which was supplemented with
physical examination. We assessed socioeconomic status using education and a household wealth index. Education
was categorised as no or primary school education only, secondary school education, or higher education, defined as
completion of trade school, college, or university. Household wealth, calculated at the household level and with
household data, was defined by an index on the basis of ownership of assets and housing characteristics. Primary
outcomes were major cardiovascular disease (a composite of cardiovascular deaths, strokes, myocardial infarction,
and heart failure), cardiovascular mortality, and all-cause mortality. Information on specific events was obtained from
participants or their family.
Findings Recruitment to the study began on Jan 12, 2001, with most participants enrolled between Jan 6, 2005, and
Dec 4, 2014. 160 299 (87·9%) of 182 375 participants with baseline data had available follow-up event data and were
eligible for inclusion. After exclusion of 6130 (3·8%) participants without complete baseline or follow-up data,
154 169 individuals remained for analysis, from five low-income, 11 middle-income, and four high-income
countries. Participants were followed-up for a mean of 7·5 years. Major cardiovascular events were more common
among those with low levels of education in all types of country studied, but much more so in low-income
countries. After adjustment for wealth and other factors, the HR (low level of education vs high level of education)
was 1·23 (95% CI 0·96–1·58) for high-income countries, 1·59 (1·42–1·78) in middle-income countries, and 2·23
(1·79–2·77) in low-income countries (pinteraction<0·0001). We observed similar results for all-cause mortality, with
HRs of 1·50 (1·14–1·98) for high-income countries, 1·80 (1·58–2·06) in middle-income countries, and 2·76
(2·29–3·31) in low-income countries (pinteraction<0·0001). By contrast, we found no or weak associations between
wealth and these two outcomes. Differences in outcomes between educational groups were not explained by
differences in risk factors, which decreased as the level of education increased in high-income countries, but
increased as the level of education increased in low-income countries (pinteraction<0·0001). Medical care (eg,
management of hypertension, diabetes, and secondary prevention) seemed to play an important part in adverse
cardiovascular disease outcomes because such care is likely to be poorer in people with the lowest levels of
education compared to those with higher levels of education in low-income countries; however, we observed less
marked differences in care based on level of education in middle-income countries and no or minor differences in
high-income countries.
Interpretation Although people with a lower level of education in low-income and middle-income countries have
higher incidence of and mortality from cardiovascular disease, they have better overall risk factor profiles. However,
these individuals have markedly poorer health care. Policies to reduce health inequities globally must include
strategies to overcome barriers to care, especially for those with lower levels of education
URI
http://hdl.handle.net/10394/32487https://www.thelancet.com/action/showPdf?pii=S2214-109X%2819%2930045-2
https://doi.org/10.1016/S2214-109X(19)30045-2
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- Faculty of Health Sciences [2404]