FPIN's Help Desk Answers
Acetaminophen for Pain Relief in Osteoarthritis
Am Fam Physician. 2020 Jul 15;102(2):113-114.
Is acetaminophen effective for relief of hip or knee pain due to osteoarthritis?
Acetaminophen is no better than placebo for relief of hip or knee pain due to osteoarthritis. Although acetaminophen does provide some pain relief, the effect is small and not clinically significant. (Strength of Recommendation [SOR]: A, based on systematic reviews and meta-analyses.) Higher daily dosages or extended-release formulations also are not effective for relieving hip or knee pain due to osteoarthritis. (SOR: A, based on a meta-analysis and a large randomized controlled trial [RCT].)
A 2019 systematic review analyzed available literature published through October 2017 to assess the benefits and harms of acetaminophen in the treatment of pain related to hip or knee osteoarthritis.1 The review included 10 RCTs with a total of 3,541 patients (mean age range = 55.3 to 70 years) who had hip or knee osteoarthritis diagnosed by imaging or clinical criteria. The acetaminophen dosage was 3,000 to 4,000 mg per day, given as three or four doses, except for one arm of one RCT that used a daily dosage of 1,950 mg. Primary outcomes included functional scores on the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC; seven RCTs; n = 3,153) and pain scores on the WOMAC (four RCTs; n = 1,294) or visual analog scale (VAS; four RCTs; n = 1,919). WOMAC pain and function scores were converted to a 0 to 100–point scale to correlate with VAS scores; a difference of 9 points or more was considered clinically significant. All of the RCTs had a low or unclear risk of bias except for two with a high risk of attrition bias. Pooled results after two to 12 weeks of follow-up showed a non–clinically significant reduction in pain scores (−26.2 points with acetaminophen vs. −23 points with placebo; seven RCTs; n = 2,355; mean difference [MD] = −3.2 points; 95% CI, −1 to −5.4). Improvement in functional scores was also not clinically significant (−14.9
1. Leopoldino AO, Machado GC, Ferreira PH, et al. Paracetamol versus placebo for knee and hip osteoarthritis. Cochrane Database Syst Rev. 2019;(2):CD013273.
2. da Costa BR, Reichenbach S, Keller N, et al. Effectiveness of nonsteroidal anti-inflammatory drugs for the treatment of pain in knee and hip osteoarthritis: a network meta-analysis. Lancet. 2017;390(10090):e21–e33.
3. Reed K, Collaku A, Moreira S. Efficacy and safety of twice daily sustained-release paracetamol formulation for osteoarthritis pain of the knee or hip: a randomized, double-blind, placebo-controlled, twelve-week study. Curr Med Res Opin. 2018;34(4):689–699.
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