Acetaminophen reduces pain from hip and knee osteoarthritis (OA), but nonsteroidal anti-inflammatory drugs (NSAIDs) are more effective in patients with moderate to severe OA pain, although individual risk factors need to be considered when choosing a therapy, according to a review in the new issue of the Cochrane Library, a publication of the Cochrane Collaboration, an international organization that evaluates medical research.¹

The new review is comprised of 15 studies involving 5986 participants. Seven of the trials compared acetaminophen (Tylenol® ) to placebo and 10 compared acetaminophen to such NSAIDs as ibuprofen (Advil®, Nuprin®, Haltran®, Medipren®, Motrin®, Midol®, Brufen®, and Genpril®), diclofenac (Cataflam®, Voltaren®, and Voltaren-XR®), a combination of diclofenac and misoprostol (Arthrotec®), and naproxen (Aleve®). The studies also included celecoxib (Celebrex®) and rofecoxib (which was once sold as Vioxx® and is no longer on the market). Aspirin was not included in the studies. On average, the trials lasted 6 weeks.

In the studies reviewed, acetaminophen showed superior effectiveness compared to placebo for reducing OA-related pain. However, acetaminophen was less effective than NSAIDs. On a scale of 0-100, pain decreased 4 more points for patients who took acetaminophen compared with those who took placebo. Pain decreased 6 more points among those who took NSAIDs instead of acetaminophen, the study showed.

There does not appear to be a major difference in side effects between acetaminophen and NSAIDs, although people taking traditional NSAIDs were more likely to have gastrointestinal (GI) side effects, the study showed. Specifically, 19% of patients in the NSAID group versus 13% in the acetaminophen group experienced GI side effects.

"The relative superiority of NSAIDs over acetaminophen is most marked in those with moderate to severe levels of pain," concludes lead author Tanveer E. Towheed, MD, associate professor of medicine and of Community Health and Epidemiology at Queen's University in Kingston, Ontario, Canada. "The benefits of NSAIDs over acetaminophen are relatively modest, and therefore, additional factors are still important to consider in the decision to use these drugs," says Dr. Towheed. These factors include patient preference, clinical judgment, cost, accessibility, and safety.

"This is consistent with what I have been preaching," Roland Moscowitz, MD, professor of medicine at Case Western Reserve University in Cleveland, Ohio, tells CIAOMed. "Acetaminophen works in some patients and is adequate and worth trying in mild pain. [However], you have to individualize therapy and consider how old they are, their pain tolerance, and what other medications they are on" in order to treat each patient effectively, he says.

Cardiovascular risk still a factor

"This report confirms a role for acetaminophen in patients with mild to moderate pain, especially those where there is a concern regarding GI risk from NSAIDs," Mark Fendrick, MD, professor of internal medicine and health management and policy at the University of Michigan Health System in Ann Arbor, Michigan, tells CIAOMed.

"Until we know for sure about the safety of COX-2 selective inhibitors and traditional NSAIDs on cardiovascular risk, it may be prudent to consider acetaminophen for first-line therapy in those who may be susceptible to GI complications or CV [cardiovascular] adverse events," he says.

Reference

1. Towheed TE, Maxwell L, Judd MG, et al. Acetaminophen for osteoarthritis (Review). Cochrane Database Syst Rev. 2006;(1):CD004257.