National trends in cyclooxygenase-2 inhibitor use since market release: nonselective diffusion of a selectively cost-effective innovation.

BACKGROUND The withdrawal of rofecoxib has highlighted concerns regarding the safety of cyclooxygenase-2 (COX-2) inhibitors. In some patients COX-2 inhibitors may be safer than nonselective nonsteroidal anti-inflammatory drugs (NSAIDs); however, the public health benefit of COX-2 inhibitors depends on their use in patients at higher than normal risk from NSAIDs. We examined trends in COX-2 inhibitor use based on risk for adverse events from NSAIDs. METHODS We analyzed data from the National Ambulatory Medical Care Survey (1999-2002) and National Hospital Ambulatory Medical Care Survey (1999-2001), nationally representative surveys of community and hospital-based outpatient practices. The main outcome measure was the proportion of patient visits in which COX-2 inhibitors were prescribed, stratified by risk of adverse gastrointestinal (GI) events from NSAIDs. RESULTS Of the visits in which either a COX-2 inhibitor or NSAID was prescribed, the frequency of COX-2 inhibitor use increased from 35% (1999) to 55% (2000) to 61% (2001 and 2002). Among patients with the lowest risk for adverse events from NSAIDs, the proportion receiving a COX-2 inhibitor increased from 12% in 1999 to 35% in 2002. Overall, increases in COX-2 inhibitor use among patients in whom NSAIDs could be used accounted for more than 63% of the growth in COX-2 inhibitor use during the period examined. CONCLUSIONS Marked increases in COX-2 inhibitor use have occurred since their release, primarily among patients at low risk for adverse events from NSAIDs. These findings demonstrate the challenge of limiting innovative therapies to the settings in which they are initially targeted and maximally beneficial.