Acetaminophen for osteoarthritis

  • Review
  • Intervention

Authors

  • TE Towheed,

  • MC Hochberg,

  • MG Judd,

  • G Wells


Dr Tanveer Towheed, Assistant Professor, Medicine, Community Health and Epidemiology, Queen's University, Room 2066 Etherington Hall, Queen's University, Kingston, Ontario, K7L 3N6, CANADA. tt5@post.queensu.ca.

Abstract

Background

Osteoarthritis (OA) is the most common form of arthritis. Published guidelines and expert opinion are divided over the relative role of acetaminophen (also called paracetamol or Tylenol) and non-steroidal anti-inflammatory drugs (NSAIDs) as first-line pharmacologic therapy. The comparative safety of acetaminophen and NSAIDs is important to consider as NSAIDs have the potential for serious gastrointestinal, renal, and cardiovascular toxicities, and acetaminophen in high dosages (greater than or equal to 2 grams per day), may also have the potential for serious upper gastrointestinal toxicity.

Objectives

To assess the efficacy and safety of acetaminophen versus placebo and versus NSAIDs (ibuprofen, arthrotec, celecoxib,naproxen, rofecoxib) for treating OA.

Search strategy

We searched the Cochrane Controlled Trials Register (Issue 3, 2002), MEDLINE (up to July 2002), and Current Contents (up to March 2002). Reference lists of identified RCTs and pertinent review articles were also hand searched.

Selection criteria

Published randomized controlled trials (RCTs) evaluating the efficacy and safety of acetaminophen alone in OA were considered for inclusion.

Data collection and analysis

Pain, physical function and global assessment outcomes were reported. Results for continuous outcome measures were expressed as standardized mean differences. Dichotomous outcome measures were pooled using relative risk and the number needed to treat was calculated.

Main results

Six RCTs and 1689 participants were included in the review. One study compared acetaminophen to placebo, and five compared acetaminophen to NSAIDs. In the placebo-controlled RCT, acetaminophen was shown to be clearly superior to placebo with a similar safety profile. The number needed to treat to achieve an improvement in pain was two. In the comparator-controlled RCTs, acetaminophen was less effective overall than NSAIDs in terms of pain reduction and global assessments but both drugs had similar efficacy in terms of improvements in functional status. No significant difference was found between the safety of acetaminophen and NSAIDs, although patients taking NSAIDS were more likely to withdraw due to GI events.

Authors' conclusions

The evidence to date suggests that NSAIDs are superior to acetaminophen for improving knee and hip pain in people with OA but have not been shown to be superior in improving function. The size of the treatment effect was modest, and the mean trial duration was only six weeks, therefore, additional considerations need to be factored in when making the decision between using acetaminophen or NSAIDs. In OA subjects with moderate-to-severe levels of pain, NSAIDs appear to be more effective than acetaminophen.

Plain language summary

Synopsis

Acetaminophen (Tylenol) and NSAIDS are both effective for treating osteoarthritis hip and knee pain

This Cochrane review summarizes evidence from six randomized controlled studies evaluating the effectiveness and safety of acetaminophen (also called paracetamol or Tylenol) in the treatment of osteoarthritis. The results show that acetaminophen was superior to placebo, and that NSAIDs were superior to acetaminophen in reducing pain and overall disease activity. However, NSAIDs were not shown to be superior to acetaminophen for improving functional status. Before making the decision to use acetaminophen and/or NSAIDs in osteoarthritis, it is important to consider patient preferences, the comparative risks of toxicity from acetaminophen and NSAIDs, prescriber's clinical judgement, cost considerations and accessibility.

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