Pain Killers And Heart Disease

The METRO ran a story today (5 July 2011) under the highly measured headline:

Painkillers ‘increase risk of heart disease’

The first four paragraphs continue this theme:-

Popular painkillers such as ibuprofen can put patients at risk of heart disease and even death, it was claimed yesterday

Taking the drugs daily can increase the chance of an irregular heart rhythm – known as atrial fibrillation – by up to 70 per cent, a new study found.

Patients who had recently started using non-steroidal anti-inflammatory drugs were 40 percent more at risk of the condition, researchers in Denmark discovered.

This could lead to a stroke and heart disease, and be fatal

If this was as far as you read, it could not be clearer; as soon as you start NSAIDs, your chances of a fatal heart atack increas 40% and if you continue, the increased risk goes up to 70%. The on-line version is phrased slightly differently but conveys the same message. Better chuck away those ibuprofen …

…Or maybe not.

As usual, there is no link to the actual research.However google found me this, published in the BMJ. This is a case-control study of “32,602 patients with a first inpatient or outpatient hospital diagnosis of atrial fibrillation or flutter between 1999 and 2008; 325,918 age matched and sex matched controls based on risk-set sampling.”

Results 2925 cases (9%) and 21 871 controls (7%) were current users of either non-selective NSAIDs or COX 2 inhibitors. Compared with no use, the incidence rate ratio associating current drug use with atrial fibrillation or flutter was 1.33 (95% confidence interval 1.26 to 1.41) for non-selective NSAIDs and 1.50 (1.42 to 1.59) for COX 2 inhibitors. Adjustments for age, sex, and risk factors for atrial fibrillation or flutter reduced the incidence rate ratio to 1.17 (1.10 to 1.24) for non-selective NSAIDs and 1.27 (1.20 to 1.34) for COX 2 inhibitors. Among new users, the adjusted incidence rate ratio was 1.46 (1.33 to 1.62) for non-selective NSAIDs and 1.71 (1.56 to 1.88) for COX 2 inhibitors.

Hmm. Those percentages in the first sentence are rounded off – to 2 significant figures they are 9.0% and 6.6% respectively. Since some of the controls were using these drugs without harm, a valid interpretation of these results might be that 2.4%, or less than 1 in 40, of cases can be attributed to these drugs. Or put another way 39 in 40 have other causes and the incident rate ratio of 1.36 clearly does not mean that taking these drugs increases your chance of heart disease by 36 % but that is how the METRO and other media outlets have interpreted the results. The last sentence shows where a similar misinterpretation has generated the 70% increase in chances figure.

A further point to note is that these relatively high risk rate ratios apply to new users. Long term users have a much lower risk rate ratio, which suggests that the body adapts to the drug and ameliorates the side effects. This doubtless has implications for dosing regimes.

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2 Responses to “Pain Killers And Heart Disease”

  1. Alan Henness Says:

    I think this same story (with a similarly misleading headline) was front page in the Daily Express today – someone Tweeted a composit pic of the front pages of several newspapers to show the prominence (or otherwise) of the NOTW phone hacking scandal.

    Looks like I was right to be skeptical of what they were claiming about the study. Now there’s a surprise!

  2. The Use and Abuse of Risk Ratios « Letting Off Steam Says:

    […] those who do not suffer Bad Thing. I looked at one example of this, and the misreporting of it, here. We might find that 15% of those hospitalised for Bad Thing undertook Activity X whereas only 10% […]

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