The study of more than 174,000 people also confirmed the benefits of statin drugs outweighed the risks for people who do not have heart disease but are at risk of getting it. The findings have prompted calls for Australia to move towards more aggressive overseas guidelines that recommend the drugs for a broader range of people.

It has long been known that by reducing cholesterol, statins prevent heart attacks and strokes in people with a history of cardiovascular disease. The drugs are already so popular about 40 per cent of Australians aged over 65 are using them.

But their use in women has been controversial, mainly because women tend to develop heart disease later in life than men, and so have not been included in as many clinical trials investigating them.

Australian and British researchers say they have resolved this with a new study, though. Their meta-analysis of 27 clinical trials – the largest ever conducted – found that statins reduced the risk of a major vascular event (heart attack, stroke, stent insertion or bypass surgery) by 21 per cent for every 1 mmol/L reduction in LDL cholesterol the drugs achieved. The risk reductions were similar in women and men.

The research, published in the Lancet, also bolstered evidence for the drugs to be used in people who do not have cardiovascular disease but exhibit risk factors for it, such as high blood pressure and obesity.

The study said in people with a less than 10 per cent risk of a vascular event over five years, statin treatment reduced their risk of an event by 32 per cent per 1 mmol/L reduction in LDL cholesterol achieved. At the moment, guidelines written by Australia's National Vascular Disease Prevention Alliance recommend the drugs for people with a five-year risk over 15 per cent.

One of the lead investigators of the study at the University of Sydney, Dr Jordan Fulcher, said this finding could prompt Australian doctors to follow the US and UK where statins are now recommended for people with a 7.5 per cent and 10 per cent risk of a vascular event over 10 years respectively.

"This study gives us a lot of reassurance that starting treatment should not be something you leave until the last minute," said the cardiologist. "Whilst the benefits must be weighed against the potential side effects, in most cases they favour statin treatment."   

Potential hazards of the drugs include muscle damage and diabetes, but the Lancet study said even in the lowest risk group examined, the number of prevented vascular events (heart attacks, strokes, stents or bypass surgery) outweighed major risks by about 18-fold.

Professor Len Kritharides, Chair of the Cardiovascular Health Advisory Committee of the Heart Foundation of Australia, said the study showed it was time to reconsider the lower risk threshold for when statin drugs should be prescribed.

"This does not mean everyone should be put on a statin, but we should define the baseline risk at which prescription is warranted," he said.

Dr Fulcher, a cardiologist, said more than 11,500 women died of hearts attacks and strokes every year.

"Far too few women realise they are at greater risk of dying from a heart attack than from breast cancer and this study should reassure them that, if advised by their doctor, they can reduce that risk by taking a statin," he said.

The research was funded by the National Health and Medical Research Council, UK Medical Research Council, British Heart Foundation and European Community Biomed Program.