The number of Britons at risk of heart disease may be overstated by 1.5 million, suggesting many could be receiving drug treatment unnecessarily, researchers said on Friday.

A study published in the British Medical Journal estimated there were 3.2 million adults under the age of 75 at high risk of developing heart disease - significantly less than the previous established estimate of 4.7 million.

The lower figure is based on a new cardiovascular risk score for the UK, called QRISK, rather than the traditional Framingham score, which was developed in the United States.

Study leader Julia Hippisley-Cox of Nottingham University said in that QRISK “takes account of social deprivation to better identify patients most at most risk of heart disease and stroke who are most likely to benefit from treatment”.

Her team tracked the progress of 1.3 million healthy individuals over a period of 12 years to April 2007 and found the Framingham index over-predicted cardiovascular disease risk by 35 percent, while the QRISK score was out by just 0.4 percent.

The discovery could have major implications for the use of cholesterol drugs called statins, which are given to patients on a long-term basis to reduce the risk of heart attacks and strokes.

The government’s drugs watchdog, the National Institute for Health and Clinical Excellence, recommends that people with a 20 percent chance of developing heart disease over the next 10 years should be offered statins.

Leading statins include Pfizer Inc.‘s Lipitor and AstraZeneca Plc’s Crestor, although cheaper generic versions are also available.