Article Text

PC0001 Effectiveness of diclofenac versus acetaminophen in primary care patients with knee osteoarthritis: A randomized clinical trial
  1. S.P. Verkleij,
  2. P.A. Luisterburg,
  3. B.W. Koes,
  4. A.M. Bohnen,
  5. S.M. Bierma-Zeinstra
  1. General Practice, Erasmus MC, Rotterdam, Netherlands


Background Guidelines recommend acetaminophen as medication of first choice when pain medication is needed. In clinical practice, however, non-steroidal anti-inflammatory drugs (NSAIDs) are widely used as first prescribed medication.

Objectives We assessed the effectiveness of diclofenac versus acetaminophen in patients with mild knee osteoarthritis (OA) who consulted their GP.

Methods This pragmatic open-label randomized controlled trial, with a 12-weeks follow-up period [1], included 104 patients aged 45 years and older, and fulfilled the clinical American College of Rheumatology (ACR) criteria for knee OA. Patients were randomly allocated to diclofenac (n=52) (maximum daily dose of 150 mg.) or acetaminophen (n=52) (maximum daily dose of 3000 mg.) for max 4-weeks. Primary outcomes were daily knee pain severity measured with an 11-point numeric rating scale (NRS) and the Knee Injury and Osteoarthritis Outcome Score (KOOS) collected with questionnaires at 3, 6, 9, and 12 weeks follow-up and daily knee pain (NRS) collected with a diary (for 4 weeks). Secondary outcome was daily medication intake. Generalized estimated equations analyses were adjusted for age, gender, and baseline pain differences.

Results At 12-weeks follow-up, NRS knee pain (β: -0.1; 95% CI: -0.9 to 0.7) and KOOS knee pain (β: -0.3; 95% CI: -7.0 to 6.4) did not differ between the groups (see figure). At 4-weeks follow-up (the end of treatment period), no differences were found regarding daily NRS knee pain and medication intake.

Conclusions At 4 and 12 weeks follow-up, there were no differences between the two treatment groups, diclofenac and acetaminophen, in reducing knee pain in patients with knee OA in primary care setting. These results endorse the recommendation of acetaminophen as “first choice medication” in (inter)national guidelines regarding primary care patients with knee OA.

  1. Verkleij SPJ, Luijsterburg PAJ, Koes BW, Bohnen AM, Bierma-Zeinstra SMA. Effectiveness of diclofenac versus acetaminophen in primary care patients with knee osteoarthritis: [NTR1485], DIPA-trial: design of a randomized clinical trial. BMC Musculoskelet Disord. 2010;11:7.

Disclosure of Interest None Declared

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