BALTIMORE, Maryland—Most osteoarthritis (OA) patients who respond to COX-2 inhibitors within 2 weeks of treatment have sustained response for at least 12 weeks, and non-responders are unlikely to develop responses between weeks 2 and 12, according to research by Clifton O. Bingham, III, MD, and colleagues published early online in Rheumatology.¹

”The overwhelming majority of the patients who responded to treatment by 2 weeks remained responders at 12 weeks, with response status largely established within 2 weeks of treatment initiation. Early identification of NSAID response or non-response may allow clinicians to better and more rapidly adjust symptomatic OA management,” Dr. Bingham wrote.

The researchers evaluated pooled data from two 26-week, double-blind, randomized trials that compared once-daily etoricoxib (Arcoxia^®, 30mg), celecoxib (Celebrex^®, 200 mg), and placebo in over 1200 patients with knee or hip OA.

Responses after 12 weeks of treatment were significantly greater for etoricoxib (59.8%) and celecoxib (57%) than with placebo (34%, p<0.001).

The investigators found that about 76% of patients who were responders at week 2 were still responders at week 12. Similarly, most non-responders at week 2 remained non-responders at week 12. The three primary endpoints were changes from baseline in the WOMAC Index Pain subscale, the WOMAC Physical Function subscale, and the patient global assessment of disease status.

The authors point out that OA treatment guidelines generally recommend a trial period of at least 4 weeks when initiating NSAID therapy before changing the drug regimen.

Translating research into practice: How long to wait for NSAID response?

“[O]ur results...suggest that NSAID response is likely to occur within the first 2 weeks of treatment. Moreover, our results show that there appear to be little benefit in extending an NSAID trial period beyond 2 weeks, as few, if any, additional responders were identified at 4 or 8 weeks,” Dr. Bingham said.

The researchers emphasize that although response to NSAIDs is most likely to appear within the first 2 weeks of treatment, treatment effects may change over time, reflecting such factors as increases in OA symptoms or patients stopping therapy due to adverse events.

This study was supported by Merck & Co.

Reference

1. Bingham CO, Smugar SS, Wang H, et al. Early response to COX-2 inhibitors as a predictor of overall response in osteoarthritis: pooled results from two identical trials comparing etoricoxib, celecoxib and placebo. Rheumatology. 2009; [Epub ahead of print] July 9, 2009.doi:10.1093/rheumatology/kep184