Paracetamol is not clinically effective for alleviating pain and improving physical function in patients with osteoarthritis, the largest analysis of randomised trials of analgesics for osteoarthritis published to date has found.
Non-steroidal anti-inflammatory drugs (NSAIDs) and paracetamol are usually the first-line treatment options for mild to moderate pain management in osteoarthritis, but paracetamol is used more frequently on a long-term basis because of the risk of cardiovascular and gastrointestinal side effects with prolonged NSAID use. However, this latest meta-analysis, published in The Lancet
on 17 March 2016, does not support this approach.
The researchers pooled data from 74 randomised trials published between 1980 and 2015, which involved 58,556 patients with osteoarthritis and compared the effects of 22 treatments and placebo on pain intensity and physical activity.
All 22 preparations of medications, irrespective of dose, improved symptoms of pain compared with placebo, but paracetamol did not achieve the minimum clinically important difference. Its effect size was -0Â·17 and to be deemed clinically important a difference of -0.37 is required, the researchers say, meaning that paracetamol had “nearly a null effect on pain symptoms at various doses”.
The maximum daily dose of diclofenac (150mg per day) was found to have the greatest impact on pain, with an effect size of -0.57. This was superior to the effects produced with the maximum doses of frequently used NSAIDs, including ibuprofen, naproxen and celecoxib.
“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,” says Sven Trelle from the University of Bern, Switzerland, who was involved in the study. “Because of this, paracetamol is often prescribed to manage long-term pain instead of NSAIDs. However, 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.”
Maureen Baker, chair of the Royal College of GPs, says: “The majority of evidence still suggests that paracetamol is a safe drug for most patients, but a number of recent studies — including this one — do cast doubt on its effectiveness at treating osteoarthritis.
“What the study doesn’t suggest is a suitable — and safe — alternative for pain management in patients with osteoarthritis. We know that alternatives, such as NSAIDs, can be effective but they can have nasty side effects for patients if they are taken over a long period of time, and whilst GPs understand and advocate lifestyle changes to patients that can help ease their pain, there is a limit to how viable these are, particularly in serious cases.”
She recommends that any concerned patients with osteoarthritis taking paracetamol on a regular basis make a non-urgent appointment with their GP, or discuss it with a pharmacist.
Despite being the leading cause of pain in older people, and affecting around 8.75 million people in the UK, osteoarthritis “is a condition that is often overlooked and its impact underestimated”, says Judi Rhys, chief executive of the charity Arthritis Care.
“We welcome research that better informs doctors on how to manage the condition,” she adds. “However, it’s also important for those living with arthritis to incorporate effective therapies into their lifestyles that don’t have side effects, including building up muscle strength, keeping moving and keeping weight at a reasonable level. These all help significantly with the pain of osteoarthritis.”
 da Costa BR, Reichenbach S, Keller N et al. Effectiveness of non-steroidal anti-inflammatory drugs for the treatment of pain in knee and hip osteoarthritis: a network meta-analysis. The Lancet 2016. doi: 10.1016/S0140-6736(16)30002-2