Scare stories: a pain in the neck

From the Herald, from the Daily Mail, on the dangers of painkillers

Researchers have today revealed the exact risk of having a heart attack or stroke from taking several common painkillers.

…

They discovered, on average, one in 330 adults who have been taking ibuprofen will experience a heart attack or stroke within four weeks.

However, the drug, costing as little as 20c a tablet and available in supermarkets and dairies, was found to be three times less dangerous than celecoxib, which will lead to one in 105 adults experiencing a heart attack or stroke.

Now, that’s obviously not true for people just taking ibuprofen for an injury or a headache. So what’s the true story?

The research paper is here. As the story says, it followed up 56,000 people in Taiwan with high blood pressure.  They were interested in a group of painkillers called “COX-selective” that have a lower risk of causing ulcers and stomach bleeding, but potentially a higher risk of heart attack and stroke.  One familiar COX-selective painkiller in NZ is Voltaren, familiar non-selective ones are ibuprofen and naproxen — but the study wasn’t looking at over-the-counter medications bought in supermarkets and dairies, just at people starting prescriptions.

Over the 7927 people starting prescriptions for ibuprofen, 24 ended up getting a heart attack or stroke, after an average of two weeks’ treatment. Of the  1,779 starting celecoxib prescriptions, 17 ended up getting a heart attack or stroke, after an average of about three weeks’ treatment.  Overall, there was a bit more than one heart attack per ten people per year for those prescribed COX-selective drugs and a bit less than one heart attack per ten people per year for those prescribed non-selective drugs.  And there’s no comparison with people who weren’t taking painkillers

You might wonder how numbers like 24 and 17 are large enough to say anything reliable. They aren’t. The “exact risk” of 1 in 330 from the lead is actually a range from something like 1 in 200 to 1 in 500, even before you consider the uncertainties in generalising from middle-aged to elderly Taiwanese people with hypertension to other groups.

This study on its own provides only very weak evidence that COX-selective drugs are more dangerous. The conclusion is plausible for all sorts of reasons, but it’s hardly conclusive.  Like it says on the packet, don’t take any of these medications for weeks at a time without consulting a more reliable source than the Daily Mail.