Paracetamol is not effective in the treatment of spinal pain and provides negligible benefits for osteoarthritis, according to an Australian study.
The evidence supporting paracetamol as the first line treatment for both conditions was weak and there were safety concerns about the recommended full dosage – up to 4,000mg/day – claimed the authors of the new study.
A recent guideline update by the National Institute for Health and Care Excellence to continue to recommend paracetamol for osteoarthritis had been “considered controversial” as a consequence, said the researchers from the University of Sydney
They carried out a systematic review and meta-analysis to examine the efficacy and safety of paracetamol for lower back pain and osteoarthritis of the hip or knee.
“Our results therefore provide an argument to reconsider the endorsement of paracetamol in clinical practice guidelines”
The study included 13 studies that looked at the effects of paracetamol use compared with a placebo. Of these, 10 trials included 3,541 patients and evaluated the use of paracetamol for osteoarthritis, and three trials included 1,825 patients on the use of paracetamol for back pain.
The study showed that paracetamol had no effect for lower back pain and did not reduce disability or improve quality of life, compared with placebo. For osteoarthritis, they found small, but not clinically important benefits in pain and disability reduction, compared with a placebo.
Paracetamol use for osteoarthritis was also shown to increase the likelihood of having abnormal results on liver function tests by almost four times, compared with a placebo, noted the authors.
The trials evaluated paracetamol and placebo usage in the short term, with the longest follow-up being six months.
Therefore, the authors acknowledge that more research is needed to determine effects over a longer period of time.
Nevertheless, they concluded that their results support the “reconsideration” of recommendations to use paracetamol for patients with low back pain and osteoarthritis of the hip or knee in clinical practice guidelines.
“We found that paracetamol is ineffective on both pain and disability outcomes for low back pain in the immediate and short term and is not clinically superior to placebo on both pain and disability outcomes for osteoarthritis,” they stated in the British Medical Journal.
“Our largest observed effect size of −3.7 points on a 0-100 pain scale, favouring paracetamol, is unlikely to be considered clinically important by patients or clinicians,” the authors said.
They added: “Our results therefore provide an argument to reconsider the endorsement of paracetamol in clinical practice guidelines for low back pain and hip or knee osteoarthritis.”
The researchers suggested paracetamol might need to be accompanied by other management strategies, such as exercises and advice, for the treatment of arthritis.
“NICE has decided to wait until the MHRA’s work is complete before doing a review”
A spokeswoman from NICE said its updated guideline on the management of osteoarthritis, published in February 2014, had recommended a range of interventions, including activity and exercise, and weight loss for obese patients, as well as drug treatments.
She said guideline update had planned to address some areas of the pharmacological management of osteoarthritis, such as use of paracetamol, which had been raised during the consultation process.
But she said the Medicines and Healthcare Products Regulatory Agency had informed NICE that it was conducting a review of the safety of over-the-counter medicines, including paracetamol.
“In response to this, NICE has decided to wait until the MHRA’s work is complete before doing a review of all pharmacological management for osteoarthritis, including paracetamol,” said the spokeswoman.
“Looking at all of the relevant painkillers together, instead of just one, will then provide a comprehensive overview of this aspect of managing osteoarthritis and allow the findings of the MHRA work to be taken into account,” she said.