Statins seem to work as well in women, but do we really know?

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Statin therapy appears to be associated with reduced risk of recurrent cardiovascular events in men and women, but does not appear to be associated with reduced all-cause mortality or stroke in women, according to a report of a meta-analysis published June 25 in the Archives of Internal Medicine. However, the researchers, the accompanying commentary and the editor of the journal all called for more research to be conducted in women.

Statins have been used to lower cholesterol levels for the last 20 years, but most of the clinical trials on the drugs have predominantly enrolled men. There have been conflicting results on the benefits of statins for women with cardiovascular disease compared with men in secondary cardiovascular disease prevention, according to the study background.

Jose Gutierrez, MD, MPH, of Columbia University Medical Center in New York City, and colleagues conducted a meta-analysis of 11 clinical trials with a total of 43,191 participants to examine whether statin therapy was more effective than placebo in preventing recurrence of cardiovascular events and all-cause mortality in men and women. Researchers also sought to determine the sex-specific effect of statins on the risk of recurrent cardiac and cerebrovascular events.

“In our results, statin therapy reduced the recurrence rate of any type of cardiovascular event, all-cause mortality, coronary death, any MI [myocardial infarction or heart attack], cardiac intervention, and any stroke type. The stratification by sex showed no statistically significant risk reduction for women taking statins compared with women taking placebo for the reduction of all-cause mortality and any type of stroke,” the authors commented.

However, the authors observed that the results of their meta-analysis “underscore” the low rate of women being enrolled in cardiovascular prevention clinical trials.

“Women represented only a fifth of the studied sample, limiting the strength of our conclusions. In our results, the benefit associated with statin administration in women did not reach statistical significance compared with placebo in at least two outcomes, all-causes mortality and any stroke type. The reason for this difference is uncertain. One possibility is that the small sample size of women limits the power of the study,” the authors noted.

The researchers added, “Although biological differences need to be further elucidated and are likely to exist, sex-specific disparities in healthcare and in biomedical research, particularly in cardiovascular health, need to be addressed from a public health perspective by promoting equal access to healthcare that includes timely screening, diagnoses and treatment of cardiovascular risk factors and disease.”

Despite the call for additional research, Gutierrez et al concluded, “this meta-analysis supports the use of statins in women for the secondary prevention of cardiovascular events.”

In an invited commentary, Fiona Taylor, PhD, HonMFPH, and Shah Ebrahim, DM, of the London School of Hygiene and Tropical Medicine, wrote: “Focusing on a lack of statistical significance in the findings for women is misleading.

"The real issue is not significance but whether the effect size in women is materially different from the effect size in men. Over-interpretation of imprecisely estimated effects is a serious problem in meta-analyses and in primary studies,” they continued.

“In the study by Gutierrez et al, the effect on stroke and all-cause mortality in women is consistent with the effect in men. If a statistical test is wanted, the appropriate p value is for the sex interaction for the outcome by sex. We suggest that statins work just as well in women as in men,” the authors concluded.

In an editor’s note about the study, Rita Redberg, MD, MSc, wrote, “This review and the accompanying commentary highlight the challenge. Are the benefits of statins less in women and risks greater than men, or are there just not enough women in the clinical trials to demonstrate benefit in women. Unless we increase inclusion of women in clinical trials and report sex-specific data, there will never be sufficient data to achieve optimal care of all of our patients.”