09/27/2011 05:24 EDT | Updated 11/27/2011 05:12 EST

Some pain meds riskier for cardiac patients than others, study suggests

TORONTO - A new study suggests some commonly consumed pain medications are riskier than others when used by people with cardiovascular problems.

The research suggests a couple of the drugs carry the same level of risk as Vioxx, which was taken off the market in 2004 over heart health concerns.

Senior author Dr. David Henry says the increased risk from this class of drugs is not significant for the average healthy individual taking the drugs occasionally.

But he says the risk profile changes in people who have already had a heart attack or who are at risk of cardiovascular events because they have diabetes, high blood pressure or a family history of heart disease.

"So we're really worried about people who might have an annual risk of maybe five per cent," said Henry, who is CEO of the Toronto-based Institute for Clinical Evaluative Sciences.

"And these are people in who a relative 40 per cent increase takes them up to seven per cent, say. And that a big increase. That absolute increase of two per cent of having a heart attack is something you would actually worry about and want to avoid."

Henry and his co-author, Patricia McGettigan of Hull York Medical School in Britain, did what's known as a meta-analysis of available studies on the cardiovascular risks of non-steroidal anti-inflammatory drugs, or NSAIDs, as they are commonly called.

A meta-analysis is when researchers pool the findings of a number of similarly conducted studies on a single topic, using the resulting larger sample size to try to bring into focus an even clearer picture than can be seen with the individual papers.

The findings from this meta-analysis were published Tuesday in the journal PLoS (Public Library of Science) Medicine.

NSAIDs include over-the-counter drugs such as Aspirin, ibuprofen and naproxen and prescription-only drugs such as diclofenac, indomethacin and etodolac.

The paper concludes naproxen is safest for people with cardiovascular risk factors. And Henry says the prescription drugs diclofenac, indomethacin and etoricoxib (not licensed in Canada) have risk profiles that suggest they should be avoided.

He makes that point in particular about indomethacin, sometimes proscribed for gout.

"It is toxic to elderly people. It has effects on the central nervous system. It makes them confused. And this study shows that it also has an elevated cardiovascular risk. So I would say that's now enough to nail the coffin on indomethacin. Doctors should stop using it," Henry said.

This research team and others have been looking at the risk posed by NSAIDs since drug giant Merck and Co. decided to halt sales of Vioxx after a study found the blockbuster drug doubled the risk of fatal heart attack and stroke in people taking it. Merck has since paid out billions of dollars in court-ordered settlements.

Vioxx was a particular type of NSAID, known as a cox-2 inhibitor. It was shown at the time that other cox-2s, such as a cousin drug Celebrex, also posed a risk, though the effect was not as large. (Celebrex remains on the market.)

Questions were also raised about other NSAIDs and their potential effect on heart health, but there was initially little evidence on which to answer the questions. Since then, Henry says, the evidence base has grown.

"We've been able to fill in some of the gaps in knowledge about some of the less commonly studied drugs. And we've been able to compare the drugs with each other for the first time," he says.

While he doesn't necessarily disagree with the general gist of the findings, outside expert Dr. Muhammad Mamdani wasn't completely convinced by Henry's paper.

"The findings are interesting and warrant concern, but by no means are conclusive," says Mamdani, a pharmacologist and director of the Applied Health Research Centre, part of the Li Ka Shing Knowledge Institute at Toronto's St. Michael's Hospital.

Mamdani notes the studies in the meta-analysis are observational studies, not the randomized controlled trials that are considered the gold standard of studies. Observational studies cannot rule out the possibility that the patients being studied are different — sicker, say — than the people for whom you are trying to provide guidance.