An estimated 27 million people in the United States have osteoarthritis (OA). Clinical guidelines for the management of this disease include both pharmacologic and nonpharmacologic therapies. This study was designed to estimate the extent to which prescription nonsteroidal anti-inflammatory drugs (NSAIDs), taken over the long-term, affect the symptoms and disease progression of OA.

Between 2004 and 2006, the Osteoarthritis Initiative (OAI) collected baseline data from four study sites, including a total of 4, 796 patients with established OA, or who were at high risk for developing OA of the knee, and were not taking an NSAID at study onset, and who began use during the study period. The participants were evaluated for four years with annual follow-up assessments. All were assessed for changes in the Western Ontario and McMaster University Osteoarthritis Index (WOMAC), as well as for radiographic progression over four years. These outcomes were compared between NSAID users and nonusers.

Among nonusers at baseline, six percent initiated treatment by one year, with 52% reporting regular use. Any prescription NSAID reported on the most recent assessment was not associated with scores for pain, stiffness or physical function on the WOMAC or with the joint space width. However, among those reporting use of prescription NSAIDs at all three of the yearly assessments, improvements were noted in patient reports of stiffness and function, with delayed joint space width progression.

This study found that long-term, but not short-term, use of NSAIDS is associated with important changes in stiffness, physical function and joint space width among patients with osteoarthritis of the knee.