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Acetaminophen “no better than placebo” at managing long-term osteoarthritis pain

Toronto, March 17, 2016

By Leslie Shepherd

Dr. Peter Jüni
Dr. Peter Jüni

Acetaminophen is no better than a placebo at reducing pain and increasing physical activity in patients with osteoarthritis, according to new research published today in The Lancet.

The study, the largest analysis of all randomized trials of medical pain relief for osteoarthritis, found that diclofenac, a non-steroidal anti-inflammatory drug, or NSAID, is the most effective short-term pain relief.

However, the authors, including Dr. Peter Jüni of St. Michael’s Hospital, caution against long-term use of NSAIDs because of known side-effects. Dr. Jüni recently became director of the hospital’s Applied Health Research Centre, an academic, not-for-profit research centre that specializes in designing and conducting clinical research, including multi-centre clinical trials.

Worldwide, 9.6 per cent of men and 18 per cent of women over the age of 60 suffer from osteoarthritis, including 4.6 million people in Canada and 26.9 million in the United States. Osteoarthritis is the leading cause of pain in elderly people. It can impair physical activity, which increases patients’ risk of obesity, cardiovascular disease, diabetes and general ill health.

Dr. Bruno da Costa, from the University of Bern in Switzerland, and colleagues, pooled data from 74 randomized trials published between 1980 and 2015. With data from 58,556 patients with osteoarthritis, the study compared the effect of 22 different medical treatments and a placebo on pain intensity and physical activity. The 22 medical treatments included various doses of acetaminophen and seven different NSAIDs.

Acetaminophen and NSAIDs are usually the first-line treatment for mild to moderate pain management in osteoarthritis, but acetaminophen is used more frequently in the long term because of the cardiovascular and gastrointestinal side effects associated with long-term NSAID use.

However, the new analysis found that acetaminophen has no clinically relevant effect compared to placebo in reducing osteoarthritic pain and increasing physical function. Of the 22 drugs that were tested, the four most effective were the NSAIDs:

  • etoricoxib 90 mg/day
  • rofecoxib 50 mg/day
  • diclofenac 150 mg/day
  • etoricoxib 60 mg/day
Among these drugs, diclofenac 150 mg/day was the most effective for both pain and physical function.

“Acetaminophen, the drug considered to be the first-line therapy in osteoarthritis in guidelines around the world, has a clinically irrelevant effect on pain and its use needs to be reconsidered,” Dr. Jüni said.

However, he said the side-effects of dicofenac and other NSAIDS mean they should not be prescribed for more than a few weeks in a row, for flares or pain peaks, leaving patients with no good pharmaceutical option for managing long-term pain for osteoarthritis.

“In the long term they need to keep active, do muscle-strengthening and aerobic exercises” he said. “We need to be honest with our patients. We currently don’t have any drug or food supplement that is both clearly effective and safe.”

This study received funding from the Swiss National Science Foundation and the ARCO Foundation, Switzerland.

This paper is an example of how St. Michael's Hospital is making Ontario Healthier, Wealthier, Smarter.

About St. Michael's Hospital

St. Michael’s Hospital provides compassionate care to all who enter its doors. The hospital also provides outstanding medical education to future health care professionals in 27 academic disciplines. Critical care and trauma, heart disease, neurosurgery, diabetes, cancer care, care of the homeless and global health are among the hospital’s recognized areas of expertise. Through the Keenan Research Centre and the Li Ka Shing International Healthcare Education Centre, which make up the Li Ka Shing Knowledge Institute, research and education at St. Michael's Hospital are recognized and make an impact around the world. Founded in 1892, the hospital is fully affiliated with the University of Toronto.

Media contacts

For more information or to arrange an interview with Dr.Juni, please contact:

Leslie Shepherd
Manager, Media Strategy, St. Michael's Hospital
416-864-6094
shepherdl@smh.ca