Prescription NSAIDs may have minimal clinical effect on knee osteoarthritis

Long-term use of prescription nonsteroidal anti-inflammatory drugs (NSAIDs) for knee osteoarthritis (OA) was associated with minimally important clinical change in stiffness, physical function, and joint space width, but not pain, a study found.

To estimate the extent to which short- and long-term use of prescription NSAIDs relieves symptoms and delays structural progression in patients with radiographically confirmed knee OA, researchers used data from the Osteoarthritis Initiative, which allowed them to study results for a 3-year period.

A total of 5,263 assessments were available to evaluate symptoms in 1,846 participants. After excluding patients for clinical characteristics or missing data, the researchers had a total of 2,890 assessments in 1,116 unique patients. Participants were evaluated for changes in the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) subscales (n=1,846). Joint space width was measured using serial radiographs and a customized software tool (n=1,116) over 4 years.

Study results appeared in the March Arthritis & Rheumatology.

Compared to participants who never reported using prescription NSAIDs, those reporting use at 1 or 2 assessments had no clinically important changes. Those reporting prescription NSAID use at all 3 assessments had, on average, a 0.88-point improvement over the follow-up period (95% CI, −0.46 to 2.22) in pain, a 0.72-point improvement (95% CI, −0.12 to 1.56) in stiffness, and a 4.27-point improvement (95% CI, −0.31 to 8.84) in function.

The average change in joint space width was 0.28 mm less (95% CI, −0.06 to 0.62) among those reporting prescription NSAID use at 3 assessments relative to nonusers. Recent NSAID use did not predict any clinically or statistically significant differences.

The researchers noted that among persons with radiographically confirmed OA of the knee, initiation of prescription NSAIDs in a 1-year period was low. “While prescription NSAID use 1 year preceding outcomes measurement showed no effect, the data were suggestive of long-term use (prescription NSAID use reported at all assessments over a 3-year period) improving patient reports of stiffness and function and a delay in disease progression. The precision of the latter estimates were limited by the number of NSAID initiators whose NSAID use persisted across the 3 years of follow-up,” they wrote.