Nonsteroidal antiinflammatory drugs or acetaminophen for osteoarthritis of the hip or knee? A systematic review of evidence and guidelines.

OBJECTIVE: The interpretation of available evidence on the relative efficacy of nonsteroidal antiinflammatory drugs (NSAID) and acetaminophen in osteoarthritis (OA) has recently been debated. This systematic review summarizes the available evidence on the efficacy of NSAID compared to acetaminophen, and compares the quality and content of clinical guidelines regarding the pharmacological treatment of OA.
METHODS: Published reports of randomized controlled trials (RCT) and clinical guidelines were identified by a systematic search of bibliographic databases and relevant websites. The quality of RCT was assessed by 2 reviewers independently using a standardized checklist. Data from these RCT were used to calculate pooled differences between groups for pain and disability. The methodology of identified guidelines was appraised using the AGREE (Appraisal of Guidelines for Research and Evaluation) instrument.
RESULTS: The search strategy resulted in the identification of 5 RCT. Statistical pooling of data from 3 trials with adequate methods and sufficient data presentation resulted in a pooled standardized mean difference for general pain of 0.33 (95% CI 0.15 to 0.51), indicating a small effect in favor of NSAID. Pooled estimates for other outcome measures were smaller. Three of the 9 identified guidelines satisfied more AGREE criteria than others, particularly regarding rigor of development. Stakeholder involvement, applicability, and editorial independence were poorly described in most guidelines. The content of recommendations regarding the use of NSAID or acetaminophen was fairly consistent.
CONCLUSION: Acetaminophen is often effective in OA and is associated with fewer adverse reactions than NSAID. Available evidence supports the recommendations of recent guidelines to use acetaminophen as initial therapy for OA in addition to nonpharmacological interventions. Further research is needed to establish the efficacy of NSAID or acetaminophen in relevant subgroups of patients. We agree with guidelines that it is important that treatment is tailored to individual patients taking into account the severity of symptoms, previous use of acetaminophen, and the patient's knowledge, expectations, and preferences.