(Medical Progress October, 2009)
I read with interest the article by Rediet Kokebie and Joel A. Block on “Managing Osteoarthritis: Current and Future Directions”1. While the article provides readers a comprehensive review of the topic, the authors, being rheumatologists, are biased towards the role of NSAIDs on osteoarthritis (OA) therapy.
For decades, there has not been a consensus on whether acetaminophen or NSAIDs should be used as first-line agent to treat knee OA2-3. Currently, many international guidelines still advocate the use of acetaminophen as the first-line medication for OA knee patients with mild to moderate pain4-7.
One reason for this ongoing debate, as rightly pointed out by the authors, is not only that “OA is more than a degenerative disease of the cartilage but also that biomechanics play a critical role in disease onset and progression”. In fact, the pain experienced by most OA patients is a mechanical pain that occurred during motion or joint loading. In a recent survey conducted in Hong Kong, 95% of OA knee patients do not have signs of inflammation at the time of screening by physicians8.
Furthermore, co-morbidities among OA knee patients are very common. According to the same Hong Kong study, among the OA knee patients presented to primary care clinics, 33% and 29% of them have co-existing cardiovascular and gastrointestinal diseases respectively8. From the literature, a meta-analysis of 138 studies demonstrated that selective COX-2 inhibitors and high dosages of ibuprofen and diclofenac were associated with increased risk of vascular events9. Another meta-analysis concluded that NSAIDs but not acetaminophen increased the risk of upper gastrointestinal bleeding10. Therefore I would have to disagree with the statement made by the authors that “despite safety concerns and recent publicity about cardiovascular risks, NSAIDs and cyclo-oxygenase (COX)-2 inhibitors remain the mainstay of OA therapy”.
As the majority of OA knee patients have only mild to moderate symptoms, I would recommend physicians to use acetaminophen as the first-line medication for OA knee patients especially when their pain most of the time is mechanical in nature. I certainly would not object the use of NSAIDs or COX-2 inhibitors to alleviate those inflammatory pain during flares but only on short-term basis.
Dr Keith KW Chan
President, Hong Kong Institute of Musculoskeletal Medicine