Statin treatment reduces risk of cardiovascular disease in women

Statin treatment reduces the risk of cardiovascular disease in women, according to a large international study, published in The Lancet.

Whether statin therapy is as effective in women as in men is debated, especially for primary prevention. This study compared the effects of statin therapy between men and women.

The study was an international meta-analysis conducted by the Cholesterol Treatment Trialists’ Collaboration, a joint initiative coordinated between the NHMRC Clinical Trials Centre, University of Sydney, Australia and the Clinical Trial Service Unit & Epidemiological Studies Unit (CTSU), University of Oxford, United Kingdom, on behalf of academic researchers representing all major statin trials worldwide.

Keech

Lead investigator Anthony Keech, professor of medicine, cardiology and epidemiology, and co-investigator Dr Jordan Fulcher, both of the University of Sydney, and colleagues performed meta-analyses on the effects of statins on 174,000 patients, undertaken by combining results from 27 different trials. Effects on major vascular events, major coronary events, stroke, coronary revascularisation and mortality were weighted per 1·0 mmol/L reduction in LDL cholesterol and effects in men and women compared with a Cox model that adjusted for non-sex differences. For subgroup analyses, the researchers used 99% CIs to make allowance for the multiplicity of comparisons.

“We analyzed this individual patient data according to sex in order to determine the efficacy and safety of statin therapy separately in men and women,” said Keech. “Analyses examined effects of statin therapy on major vascular events, and subsidiary end points, cause specific mortality and cancer. Effects on major vascular events were also examined in primary and secondary prevention populations as well as according to patient’s absolute risk of a future cardiovascular event. To compare results between men and women more reliably we developed a model which accounted for differences in baseline characteristics between the sexes.”

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Overall, statin treatment reduced the risk of a major vascular event (heart attack, stroke, bypass surgery, 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 cardiovascular disease.

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Such benefits from statin treatment translated into a significant reduction (9% risk reduction for each 1 mmol/L reduction in LDL-cholesterol) in the overall risk of death in both men and women, a finding in women which has not been previously reported by any individual statin trial.

Dr Fulcher

Statins have a similar effectiveness in men and women at all levels of vascular risk, the researchers concluded. “These findings can give reassurance to clinicians that when treating a female patient they can apply the same risk based considerations when prescribing statin therapy as for men,” said Dr Fulcher.

“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,” Keech said.

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Heart attacks and stroke are major problems in women just as they are in men. In Australia more than 11,500 women die of these two diseases every year.

“Overall, these cardiovascular benefits translate into significant reductions in all-cause mortality for both sexes. In women this finding was particularly important because no individual randomized controlled trials have demonstrated an independent all-cause mortality reduction for women before. Therefore decisions to treat patients with statins can and should be made knowing they are effective in both men and women,” Keech said.

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“All patients hospitalized with a cardiovascular event, non-fatal heart attack, ischemic stroke or coronary revascularization [stenting or bypass surgery] should be prescribed a statin if they are not already, providing there are no contraindications to statin therapy,” Dr Fulcher said. “We have decisive evidence that for the secondary prevention of cardiovascular disease, statins confer significant protection from vascular events and related mortality for both women and men. Any residual uncertainty, which unfortunately has existed in some circles, about the benefits of statins for women in this context should now be laid to rest.”

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Equally importantly, a greater awareness of the cardiovascular risk of women is needed in those patients who don't already have cardiovascular disease, according to the researchers, in terms of screening them for risk factors and considering their predicted cardiovascular risk according to those risk factors.

“Since we now also have evidence showing that the current US/UK/European guidelines for when to consider prescribing statins are supported by the findings of this study for women and men, we should be prudent in applying these guidelines in our care of women as well as men,” Dr Fulcher said.

Treatment effects in women have been more difficult to demonstrate because women have a lower absolute risk of events than men of the same age, and women have been significantly under-represented in trials, according to Keech.

“This collaboration of individual patient data for randomized statin trials is the largest in the world, and is to the best of our knowledge the largest for any class of cardiovascular medications,” Keech said. “Therefore these analyses provide the most reliable estimate of treatment effects of statins in women that is available.

“As well as being able to examine and demonstrate similar benefits of statin therapy across all levels of predicted vascular risk examined, we demonstrated a significant all-cause mortality reduction for women taking statins, a finding which was not reported in any of the individual trials,” Keech concluded.