Higher cardiovascular mortality in low- and middle-income countries [PURE study]

1. Although the burden of cardiovascular risk factors was highest in high-income countries, the rate of major cardiovascular events was significantly greater in low- and middle-income countries. 

2. This is likely due to greater access to preventive therapies and control of risk factors in high-income countries. 

Evidence Rating Level: 2 (Good)

Study Rundown: The Prospective Urban Rural Epidemiologic (PURE) study investigated the global burden of noncommunicable diseases and involved over 150,000 participants from 17 low-, middle-, and high-income countries. Findings from the study on cardiovascular risk and the incidence of cardiovascular events were published in this article. The study found that the burden of cardiovascular risk factors was highest in high-income countries yet the rate of major cardiovascular events was lowest in these countries. Meanwhile, the rate of non-major cardiovascular events was highest in high-income countries. This trend could be explained by greater access to preventive therapies and higher educational levels in high-income countries. A strength of the study is the inclusion of both urban and rural communities as well as countries of varied socioeconomic levels. Limitations of the study include lower follow-up rates in urban communities of low-income countries and limited detection of events in low-income countries compared to high-income countries due to differences in access to health care facilities.

Click to read the study, published today in NEJM

Relevant Reading: Estimating modifiable coronary heart disease risk in multiple regions of the world: the INTERHEART modifiable risk score

In-Depth [prospective cohort]: This study included 156,424 adults from 628 urban and rural communities in 17 countries. Data was collected on major cardiovascular events (death from cardiovascular causes and nonfatal stroke, myocardial infarction, and heart failure) and nonmajor cardiovascular events (all other cardiovascular events that led to hospitalization). Risk-factor burden was calculated using the validated INTERHEART Risk Score. A score of 0 to 48 was assigned with higher scores indicating greater burden.

The high-income countries recorded the highest mean INTERHEART Risk Score of 12.89 compared to middle- and low-income countries which had mean scores of 10.47 and 8.28, respectively (P<0.001). The use of antiplatelet drugs was highest in high-income countries, intermediate in middle-income countries, and lowest in low-income countries. The same pattern held true for the use of beta-blockers, renin-angiotensin system blockers, statins, and coronary revascularization. Over a mean follow-up of 4.1 years, there were 3900 deaths. The rate of major cardiovascular events was lowest in high-income countries, intermediate in middle-income countries, and highest in low-income countries (P<0.001). This pattern was reversed for the rate of nonmajor cardiovascular events with the highest rate occurring in high-income countries and the lowest rate in low-income countries (P<0.001).

Image: PD

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