Long-term oral non-steroidal anti-inflammatory drugs (NSAIDs) do not reduce joint inflammation for people with osteoarthritis of the knee and may even increase it, researchers have found.
The research team from the University of California investigated the impact of NSAIDs on synovitis, the inflammation of the membrane lining the joint. The research was presented at the annual conference of the Radiological Society of North America on 21 November 2022 in Chicago, Illinois.
NSAIDs, such as ibuprofen, diclofenac and naproxen, are common treatments for pain and stiffness caused by osteoarthritis.
The researchers used MRI scans to monitor the progress of synovitis in 1,070 people with moderate-to-severe osteoarthritis of the knee over the course of four years. They compared 277 people who had been treated with NSAIDs for at least one year, with 793 people who had not been treated with NSAIDs.
People who had been treated with NSAIDs for at least one year had worse synovitis (measured by evidence of joint inflammation and cartilage quality) at the start of the study, compared to the control group who were not taking NSAIDs.
In addition, their synovitis worsened more during the four-year study, compared with people not treated with NSAIDs.
Study author Johanna Luitjens, postdoctoral scholar in the Department of Radiology and Biomedical Imaging at the University of California, said this indicated that there were “no protective mechanisms from NSAIDs in reducing inflammation or slowing down progression of osteoarthritis of the knee joint”.
She said that this could be because the usual anti-inflammatory effect from NSAIDs does not prevent synovitis, or because patients who have synovitis and are prescribed NSAIDS “may be more physically active due to pain relief, which could potentially lead to worsening of synovitis”.
The researchers adjusted their results to account for different physical activity levels.
Luitjens called for prospective randomised controlled studies to further investigate the anti-inflammatory properties of NSAIDs for people with osteoarthritis.
Commenting on the findings, Wendy Holden, honorary consultant rheumatologist and medical advisor to the charity Arthritis Action, said the study added to concerns over adverse effects of long-term oral NSAIDs.
The National Institute for Health and Care Excellence advised caution over their use in updated guidance in October 2022, citing concerns over potential gastrointestinal, renal, liver and cardiovascular toxicity.
“This study adds weight to this recommendation and suggests that NSAIDS might also worsen joint inflammation, at least on an MRI scan,” Holden said.
But, she added: “Currently, no firm conclusions can be made on whether NSAIDs are harmful in terms of outcome for patients with osteoarthritis. More clinical studies are needed to test this theory.
“For now, topical NSAIDs are safe and effective for most people, and oral NSAID use should be at the lowest possible dose for the shortest possible time.”