Paracetamol is ineffective at treating hip and knee pain caused by osteoarthritis, new research has shown.
Osteoarthritis is the most common form of arthritis, affecting one in 10 men and nearly one in five women over the age of 60.
The study, published in The Lancet, suggests that the drug is ineffective regardless of dosage. The researchers found that diclofenac — a strong anti-inflammatory — was the most effective osteoarthritis treatment, but warned against long-term use of the drug, saying it was only appropriate for intermittent pain relief.
Paracetamol is popular with arthritis patients because it has fewer side effects than other painkillers, but in 2013 NICE advised GPs to stop prescribing the drug for osteoarthritis treatment because of the side effects associated with long-term use. These can include kidney, heart and intestinal problems.
The researchers, from the University of Bern in Switzerland, say that paracetamol does not meet the minimum clinically important effect for pain reduction in osteoarthritis patients, and that they ‘see no role for single-agent paracetamol for the treatment of patients with osteoarthritis irrespective of dose’. They also found that paracetamol was just five per cent more effective than a placebo.
The study’s lead author, Dr Sven Trelle, 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.
‘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.’
A meta-analysis of randomised controlled trials is the gold standard when assessing an intervention. We know that paracetamol has a vastly weaker anti-inflammatory effect compared to NSAIDs (non-steroidal anti-inflammatory drugs, eg diclofenac) and clinical experience does inform the premise of the article — that single-agent paracetamol does little when it comes to arthritic pain. The study is thus consistent at multiple levels and does not downplay the side effects of the most effective therapy, diclofenac.
Research score: 4/5