Findings from a large international prospective study reveal that only about half of people with known cardiovascular disease or previous stroke worldwide take any effective medication, even so much as aspirin, to prevent future events.
In the poorest countries studied, fewer than one-fifth were on medication.
The study revealed what investigators described as global underuse of preventive medications, and "striking variations" in prevalence of preventive drug use, with the economic status of countries accounting for most of the variation seen.
Even the use of cheap and widely available aspirin, the most commonly used antiplatelet drug in the world, varied sevenfold between low-income and high-income countries. Use of statins was seen as varying 20-fold, with almost no use in Africa, and very little in South Asia.
For their research, published Aug. 28 in the Lancet (doi:10.1016/S0140-6736[11]61215-4), Dr. Salim Yusuf of Hamilton Health Sciences and McMaster University in Hamilton, Ontario, and his colleagues, looked at use of antiplatelet drugs, beta-blockers, ACE inhibitors, angiotensin-receptor blockers, and statins in an epidemiologic cohort of 153,996 people aged 35-70 years in 17 countries during 2003-2009. More than half (56%) of participants were women.
Of the study subjects, 5,650 reported having a prior coronary heart disease event, and 2,292 reported prior stroke. The likelihood of these subjects being on any of the four effective drug types had mostly to do with the economic status of their country of residence, Dr. Yusuf and his colleagues found.
Individual-level factors, such as age, sex, education, smoking, body-mass index, and hypertension or diabetes status, accounted for about a third of the variation, while country income accounted for the rest. In all settings, fewer women than men took the drugs, although Dr. Yusuf and his colleagues described no clear reason why. Urban or rural residency was not seen as accounting for as much variation after researchers adjusted for other factors.
While all but 11% of people who needed preventive drugs received them in high-income countries such as Canada and Sweden, 45% of those living in upper–middle-income countries such as Poland were not receiving any preventive drugs.
In lower–middle-income countries such as Colombia, 69% of patients in need were unmedicated. In the lowest-income countries studied, the share of unmedicated people was seen as higher than 80%, and higher still in Africa.
Overall, antiplatelet drugs were taken by only 25% of study subjects, beta-blockers by 17%, ACE inhibitors or ARBs by 20%, and statins by 15%.
However, use of specific drug types also varied widely by region, with only 1% of Africans and 2% of Chinese taking statins, compared with 52% of North Americans and Europeans.
Use of preventive drug therapy was far from ideal, even in the high-income countries studied, the authors found, noting that in Canada, Sweden, and the United Arab Emirates as a group, only 61% of patients who had had a stroke received a blood-pressure–lowering drug.
Dr. Yusuf and his colleagues’ research was supported by grants from a number of pharmaceutical firms, including AstraZeneca, Sanofi-Aventis, Boehringer Ingelheim, Servier, GlaxoSmithKline, Novartis, and King Pharma. The researchers described as a limitation of their study the fact that it relied on self-reporting of cardiovascular events and stroke.
In an editorial comment (doi:10.1016/S0140-6736[11]61302-0) accompanying the researchers’ study, Dr. Anthony M. Heagerty of the Cardiovascular Research Group at the University of Manchester (England) described the findings as containing a "stark and alarming message" about underuse worldwide.
The results are "especially disappointing" in the high-income countries, Dr. Heagerty wrote, "where well-developed health care provision should ensure the implementation of best practice and any concerns about optimum data gathering will be small." Dr. Heagerty ascribed some of the underprescribing to "fears about polypharmacy" and a focus on reduction of risk factors instead of risks to the individual patient."
Dr. Heagerty disclosed having received consulting and speaking fees from Servier, Merck Serono, Novartis, and DaiichiSankyo.