The effect of short-term and long-term use of nonsteroidal antiinflammatory drugs (NSAIDs) on structural change is equivocal. The aim of this study was to estimate the extent to which short- and long-term use of prescription NSAIDs relieve symptoms and delay structural progression among patients with radiographically confirmed osteoarthritis (OA) of the knee.
We applied a new-user design among participants with confirmed OA not reporting NSAID use at the time of enrollment in the Osteoarthritis Initiative. Participants were evaluated for changes in the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) subscales (n = 1,846) and joint space width was measured using serial radiographs and a customized software tool (n = 1,116) over 4 years. We used marginal structural modeling to estimate the effect of NSAIDs.
Compared to participants who never reported prescription NSAID use, those reporting use at 1 or 2 assessments had no clinically important changes, but those reporting prescription NSAID use at all 3 assessments had, on average, 0.88 point improvement over the followup period (95% confidence interval [95% CI] -0.46 to 2.22) in pain, 0.72 point improvement (95% CI -0.12 to 1.56) in stiffness, and 4.27 points improvement (95% CI -0.31 to 8.84) in function. The average change in joint space width was 0.28 mm less among those reporting NSAID use at 3 assessments relative to nonusers (95% CI -0.06 to 0.62). Recent NSAID use findings were not clinically or statistically significant.
Long-term, but not short-term, NSAID use was associated with an a priori-defined minimally important clinical change in stiffness, physical function, and joint space width, but not pain. While showing modest clinical importance, the estimates did not reach statistical significance.