The international study, published in The Lancet, confirms that statins are beneficial not only to women who have already had a cardiovascular event such as a heart attack or stroke – but also for women who, while they have not yet got heart disease, are at an increased risk of such diseases.
Professor Anthony Keech of the University of Sydney, who led the study, said: ‘These results resolve a major uncertainty about the value of treating women with statin therapy, and reinforce the need for recommendations to treat women to be included in national and international guidelines.’
Co-investigator Professor Colin Baigent of the Clinical Trial Service Unit (CTSU), University of Oxford, said: ‘Heart attacks and stroke are major problems in women just as they are in men. Many women at increased risk of such disease could avoid them by taking a statin.’
Heart disease and stroke in women are significant global health problems. In the UK around 60,000 women die of these two diseases every year.
It has long been known that statin medications, in reducing low-density lipoprotein (LDL) cholesterol or ‘bad’ cholesterol, prevent heart attacks and strokes in people at risk of these diseases.
However, women tend to develop heart disease later in life than men, so have been under-represented in most clinical trials of statin drugs. As a result, the benefits of statin therapy in women have been uncertain, especially in women without any previous history of heart disease.
The new study assessed the effect of statins in 46,675 women and 127,474 men who had taken part in 27 clinical trials – the largest statin trial database in the world.
Overall, statin treatment reduced the risk of a major vascular event (heart attack, stroke, need for coronary revascularisation stenting and bypass surgery, or cardiac death) by 21% for each 1 mmol/L reduction in LDL cholesterol achieved.
The percentage risk reductions were similar in women and men, irrespective of any history of heart disease.
This benefit of statin treatment translated into a 9% reduction in overall risk of death in both men and women for each 1 mmol/L reduction in LDL cholesterol.
Many women without a history of heart disease are at low risk of experiencing a major vascular event. The new analysis led by the British and Australian researchers showed that there was some benefit even among the lowest risk group examined (women with less than 10% risk of a heart attack or stroke over 5 years). For every 1mmol/L LDL cholesterol reduction, 12 vascular events would be avoided in men and 9 in women for every 1000 treated over five years. The benefits of statin therapy exceeded the known harms by nearly 20 fold in both sexes.
There has been a recent worldwide shift towards recommending treatment with statins to people without existing heart disease but with a sufficiently high risk of future disease. The researchers say the results of this study will reassure doctors that these risk-based guidelines for treatment can be applied to men and women equally.
Professor Peter Weissberg, medical director of the British Heart Foundation, which helped fund the study, said: ‘This analysis of the effects of statins on 174,000 patients, undertaken by combining results from 27 different trials, shows beyond any reasonable doubt that women gain the same benefits from statins as men.
‘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.’
Professor Len Kritharides, Chair of the Cardiovascular Health Advisory Committee of the Heart Foundation of Australia, said: ‘[These results] show unequivocally that statins similarly benefit men and women in preventing heart attacks without evidence of serious harm. Importantly, the study also demonstrates that treatment with statins improves overall survival in men and women. These results should give great encouragement to patients and their doctors that lowering cholesterol with statins prevents cardiovascular disease.’
The study was conducted by the Cholesterol Treatment Trialists’ Collaboration, a joint initiative coordinated between the NHMRC Clinical Trials Centre at the University of Sydney and the Clinical Trial Service Unit (CTSU), University of Oxford, on behalf of academic researchers representing all major statin trials worldwide. The work is funded by the UK Medical Research Council, Australian National Health and Medical Research Council, British Heart Foundation, and the European Community Biomed Program.
University of Oxford.