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Acetaminophen no better than placebo for osteoarthritis pain

Acetaminophen should play no role in the treatment of pain related to osteoarthritis, no matter the dose, according to data published in The Lancet.

According to the researchers, diclofenac, at 150 mg, is the most effective nonsteroidal anti-inflammatory drug (NSAID) available. However, when considering the known safety profile of diclofenac and other NSAIDs, physicians need to use caution when selecting treatments for each individual patient.

“Osteoarthritis is the most common form of joint disease and the leading cause of pain in elderly people,” Bruno R. da Costa, PhD, of the University of Bern, in Switzerland, and colleagues wrote. “… Management of osteoarthritis pain is based on a sequential hierarchical approach, with NSAIDs being the main form of treatment. … When prescribing NSAIDs, clinicians are faced with a myriad of different preparations and dosages, which poses a challenge to clinical decision making.”

To determine the effectiveness of various NSAID preparations and doses for osteoarthritis pain, the researchers conducted a network meta-analysis, examining randomized trials comparing NSAIDs, acetaminophen or placebo. They used the Cochrane Central Register of Controlled Trials (CENTRAL) to search for relevant articles published between Jan. 1, 1980, and Feb. 24, 2015, with at least 100 participants per group.

The researchers identified 74 randomized trials, including 58,556 participants, for their analysis. There were 23 nodes concerning seven unique NSAIDs, acetaminophen or placebo.

According to the researchers, all interventions, no matter the dose, improved osteoarthritis pain when compared with a placebo. For five interventions, including acetaminophen, there was not enough statistical evidence available to support superiority when compared with placebo. In six preparations — diclofenac 150 mg per day, etoricoxib 30 mg per day, 60 mg per day and 90 mg per day, and rofecoxib 25 mg per day and 50 mg per day — the probability the difference to placebo is at or below a minimum clinically important effect for pain reduction was 95%. Diclofenac at 150 mg per day and etoricoxib at 60 mg per day had the highest probability of effectiveness, with 100%.

“Our analysis suggests that [acetaminophen] is clinically ineffective and should not be recommended for the symptomatic treatment of osteoarthritis, irrespective of the dose,” da Costa and colleagues wrote. “Conversely, diclofenac at the maximum daily dose of 150 mg/day is most effective for the treatment of pain and physical disability in osteoarthritis, and superior to the maximum doses of frequently used NSAIDs, including ibuprofen, naproxen and celecoxib. … Since all NSAIDs with available safety data were associated with clinically relevant gastrointestinal and cardiovascular harms, type and dose of NSAID should be chosen on the basis of the analgesic effectiveness reported in this analysis.”

Disclosure: da Costa reports no relevant financial disclosures. See the full study to for the full list of relevant financial disclosures.