Doctors are prescribing drugs at doses that were based on old data that has not taken into account lifestyle changes, researchers from Stanford School of Medicine say.
At least 11 million people in the US alone are being incorrectly prescribed their heart medication and are taking the wrong dose based on their risk.
As a result, "many Americans are being recommended aggressive treatments that they do not need according to current guidelines," says lead researcher Steve Yadlowsky.
Conversely, African-Americans could be taking doses that are too low; again, the old data is to blame, and is under-estimating their risk for a heart attack or stroke.
Heart medication is based on a series of calculations known as PCEs, or pooled cohort equations, that help the physician decide on the appropriate type of drug and the dose. The prescription could be for anything from aspirin, a statin or an anti-hypertensive for lowering blood pressure levels.
The problem is that the PCEs are based on data sets created in the 1940s, and the diet and lifestyles of those times meant that the risk of a heart attack or stroke was 20 per cent higher than it is today. "A lot has changed in terms of diets, environments and medical treatment since the 1940s, so relying on our grandparents' data to make treatment choices is probably not the best idea", said researcher Sanjay Basu.
Basu and his research team have updated the PCEs with more recent data and are hoping this will have a knock-on effect with more accurate, and safer, prescribing.