TORONTO - Statins appear to reduce the risk of death following a first heart attack - but the benefit from these widely used cholesterol-lowering drugs seems less pronounced in women than in men, a Canadian study suggests.
The McGill University study, an analysis of six years of health records for more than 38,000 Quebec heart attack patients, found that those subsequently prescribed one of six popular brands of statins had lower rates of death from cardiac-related and other causes of death compared with those not given the drugs.
"We basically found that there is effectiveness in both sexes," principal investigator Dr. Louise Pilote said of statins, "but the effectiveness appears to be greater in men than in women, and that in both sexes it increases over time."
Statins are believed to work by lowering LDL - the so-called bad cholesterol - which in turn prevents progression of dangerous plaque buildup in arteries, which can lead to a heart attack. The statins included in the study were atorvastatin (Lipitor), pravastatin (Pravachol), simvastatin (Zocor), lovastatin (Mevacor), rosuvastatin (Crestor) and fluvastatin (Lescol).
But a growing number of studies suggests the drugs aren't all things to all people - and there are some experts who say the benefits of statins still haven't been definitively proven in either sex.
Even though women don't appear to respond the same way as men do to the anti-cholesterol medications, doctors usually prescribe them for the same reasons and at similar doses for both sexes, Pilote, director of internal medicine at McGill, said Monday from Montreal.
There are a number of possible reasons for the gender difference when it comes to statins.
"It may be that women require a larger dose than men" to get a similar effect, she hypothesized.
"Another possibility is that the response to the statin itself from a biological point of view is different" for men and women, added Pilote, whose study is published in Tuesday's edition of the Canadian Medical Association Journal.
But Dr. Jim Wright, medical director of the Therapeutics Initiative at the University of British Columbia, criticized the researchers' interpretation, saying the benefits they attribute to statins are exaggerated, based on the data they present and what's known from previous studies.
He also questions the suggestion that women may need a higher dose than their male counterparts. Because women's weights on average are lower than men's, a standard dose would actually provide a higher concentration of drug in women than in men, explained Wright, an internist and clinical pharmacologist who specializes in hypertension.
"I think the only plausible explanation (for the difference seen between men and women on statins) is that women are being harmed by the drugs and it's leading to deaths that are presently unrecognized to be caused by the statins," he said.
"This is pretty good proof of it," he said of the McGill study, "because the dose and the concentration and the effect on cholesterol are all expected to be greater in women than in men - and you're seeing a lesser reduction in death."
Still, Wright called the study important for sending up another red flag about how men and women respond differently to medications - and for questioning the reasons why.
"I think it should be waking people up to the fact that we should be really looking at this carefully. We should be trying to answer this question."
In that, at least, Wright and the McGill researchers agree.
"The idea is that we should not assume that the biological effect or the pharmacological response is necessarily the same in men as women," Pilote stressed. "So it suggests that whenever we study drugs in clinical trials, we have to make sure we include as many women as men so we can look at the comparison in both sexes."
