A combination of generic drugs can slash the risk of a fatal heart attack or stroke for high-risk patients. If they can get them.

Only a tiny fraction of people who have had a heart attack or stroke take the drug combination that slashes their risk of a second episode by 80 percent.

People who have had a heart attack or stroke are generally prescribed a combination of aspirin, beta-blockers, and blood pressure and cholesterol-lowering medications to lower the risks of a second attack.

The drugs are effective enough that the World Health Organization has set targets to ensure that at least half of eligible patients get the drugs by 2025.

A study published overnight in The Lancet found that there’s a long way to go to reach those targets. Just 3 percent of patients worldwide with known cardiovascular disease take all four medications. Only 1 in 10 take at least three of the four.

Heart disease is the single largest cause of death worldwide. If everyone who needed the cardiovascular drugs took them, roughly 2.5 million lives would be saved every year.

“This is a really remarkable paper because it starts to describe the scope of limited availability and scope of cardiovascular medications on a scale that hasn’t been done before,” Dr. Mark Huffman, M.P.H., an assistant professor of epidemiology and cardiology at Northwestern University, told Healthline.

Huffman was not involved in the study but has collaborated in the past with its senior author.

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Globally, patients who need the drugs often find that the medications cost too much or simply aren’t available, the study found.

“We’ve known for a very long time that they are effective and they’re produced generically, so it’s surprising that they’re not available,” said Rasha Khatib, Ph.D., a population health researcher at McMaster University in Ontario and an author of the study.

In countries with lower per capita incomes, the drugs were not widely available, the study found. Across the board, urban residents had better access to them than their rural counterparts. That gap was more pronounced in poorer countries.

In more affluent countries, the medicines are generally available and affordable. Still, only a third to half of eligible patients get them.

Though the issues are different in developing countries, Huffman said that the basic problem — patients who need the drugs don’t take them — remains the same. In developed countries, between a third and half of patients who have heart disease or a previous stroke still don’t take them.

“It’s mostly an adherence problem,” Khatib said, due to the failures in the healthcare system. The affluent countries in the study included Canada but not the United States.

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Cost falls under the umbrella of adherence problems, Huffman said.

In one U.S. study, Harvard researchers paid for the drugs for patients who had just had one heart attack and found that the number who took the medications rose.

To improve access to the drugs worldwide, international health groups will likely have to work with manufacturers and distributors. Arrangements to provide the drugs free of cost, as has been done with HIV drugs, may also be considered.

The study, funded by Canadian patient advocacy organizations, drug manufacturers and other sources, analyzed availability and costs of cardiovascular disease medicines in pharmacies gathered from 596 communities in 18 countries between 2003-2013.

Researchers defined “affordable” as costing less than 20 percent of nonessential household income.

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