Research News

Paracetamol does not reduce pain or improve function in osteoarthritis, study shows

BMJ 2016; 352 doi: (Published 18 March 2016) Cite this as: BMJ 2016;352:i1609
  1. Susan Mayor
  1. London

Paracetamol had virtually no effect on pain or function in patients with osteoarthritis, shows a large meta-analysis that found the non-steroidal anti-inflammatory drug (NSAID) diclofenac to be more effective.1

Paracetamol and NSAIDs are commonly used to treat pain associated with osteoarthritis. But the wide range of different preparations and dosages complicates prescribing decisions, and systematic reviews have previously reported their effects on reducing pain when compared with placebo, so this has not allowed for comparisons between different agents.

To compare different preparations and doses of NSAIDs and paracetamol, researchers pooled data from 74 randomised trials published from 1980 to 2015 including a total of 58 556 patients with osteoarthritis. They included all large scale trials comparing NSAIDs, paracetamol, and placebo for the treatment of osteoarthritis pain.

Results showed that diclofenac (150 mg/day) was the most effective in reducing pain and improving physical function (effect size for pain reduction –0.57 (95% credibility interval –0.69 to –0.46)). Paracetamol had nearly a null effect on pain symptoms at all doses: the effect size was –0.17, and the minimum clinically important difference for chronic pain was –0.37.

The researchers, led by Bruno da Costa, of the Institute of Primary Health Care at the University of Bern in Switzerland, said, “NSAIDs are usually only used to treat short term episodes of pain in osteoarthritis, because the side effects are thought to outweigh the benefits when used longer term. Because of this, paracetamol is often prescribed to manage long term pain instead of NSAIDs.”

They added, “Our results suggest that paracetamol at any dose is not effective in managing pain in osteoarthritis, but that certain NSAIDs are effective and can be used intermittently without paracetamol.” However, they warned about the potential harmful effects of NSAIDs, including gastrointestinal complications and cardiovascular risk.

An accompanying commentary noted that the meta-analysis did not include other widely used NSAIDs, probably because no large trials had included them.2 But the authors, led by Nicholas Moore, of the University of Bordeaux in France, said, “The most remarkable result is that paracetamol does not seem to confer any demonstrable effect or benefit in osteoarthritis, at any dose.”

They concluded, “Paracetamol has been on the market for as long as most of us remember. Its efficacy has never been properly established or quantified in chronic diseases, and is probably not as great as many would believe.

“Many patients could be suffering needlessly because of perceived NSAID risks and paracetamol benefits which might not be real.”


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