Cheap generic drugs to cut heart risk are substantially underused worldwide, with more than half of people who could benefit estimated not to be getting any of four simple and effective types of medicine, researchers say.
Underuse is most acute in low-income countries, where around 80 percent of people with a history of heart disease or stroke take none of the drugs, according to the largest clinical study to date on the issue.
But rich countries in the developed world are also not immune.
Globally, around 60 percent of people with heart disease and up to half those who have had a stroke might not be taking a bloodthinner like aspirin, a cholesterol-lowering statin or one of two types of blood pressure pills, known as beta-blockers and ACE inhibitors or ARBs.
The findings were presented at the European Society of Cardiology annual meeting and published online in the Lancet medical journal, where they were described as "stark and alarming" in a commentary by Dr Tony Heagerty of the University of Manchester.
The disappointing uptake of proven treatments will provide more ammunition for campaigners arguing that the world needs to do more to confront the problem of non-communicable diseases (NCDs), like cancer, lung problems and cardiovascular disease.
Cardiovascular disease affects more than 100 million people worldwide and 75 percent are in low- and middle-income countries, where access to medical care is often limited.
The United Nations has scheduled a summit in September on NCDs and some health organizations are concerned that rich countries are blocking progress by not agreeing to set clear UN targets.
The study by Dr Salim Yusuf of Canada's McMaster University and colleagues looked at 154,000 adults from 17 countries, including Sweden, Brazil, China and India.
More than 7,500 of these self-reported either a history of coronary heart disease or stroke. Overall, use of preventative drugs in this group was low with bloodthinners, mainly aspirin, taken by only 25.3 percent of individuals, beta-blockers by 17.4 percent, ACE inhibitors or ARBs by 19.5 percent and statins by 14.6 percent.
Blood pressure medicines used to be among the biggest sellers for pharmaceutical companies, but most are now off patent and available as cheap generics.
Statins, including Pfizer's Lipitor and AstraZeneca's Crestor, are still multibillion-dollar products but they also face increasing generic erosion, with the decline set to quicken when Lipitor loses U.S. patent protection later this year.
The researchers acknowledged their study had limitations, with self-reporting by patients potentially giving a misleading picture of disease incidence in some cases. They also said it was unclear to what extent the findings could be generalized to entire regions.
But the results, which received funding from various sources, including drug companies, is in striking contrast to some smaller studies based on patients treated in hospitals or clinics that had indicated far higher drug use.
Yusuf said his team's study showed a different real-world picture of preventative treatment in the community, where many people regularly dropped out of medical care and stopped taking medicines after initial heart problems.
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