Celecoxib compared with sustained-release paracetamol for osteoarthritis: a series of n-of-1 trials

Objective. To assess the use of n-of-1 trials for short-term choice of drugs for osteoarthritis, with particular reference to comparing the efficacy of sustained-release [SR] paracetamol with celecoxib in individual patients. Methods. Evaluation of community-based patients undergoing n-of-1 trials which consisted of double-blind, crossover comparisons of celecoxib 200 or 400 mg/day with sustained-release paracetamol 1330 mg three times a day in three pairs of 2 week treatment periods per drug with random order of the drugs within pairs. Outcomes evaluated were pain and stiffness in sites nominated by the patient, functional limitation scores, preferred medication, side effects and changes in drug use after an n-of-1 trial. Participants were 59 patients with osteoarthritis in multiple sites (hip 6, knee 24, hand 6, shoulder/neck 8, back 14, foot 5), with pain for ≥1 month severe enough to warrant consideration of long-term use of celecoxib but for whom there was doubt about its efficacy. Forty-one n-of-1 trials were completed. Results. Although on average, celecoxib showed better scores than SR paracetamol [0.2 (0.1) for pain, 0.3 (0.1) for stiffness and 0.3 (0.1) for functional limitation], 33 of the 41 individual patients (80%) failed to identify the differences between SR paracetamol and celecoxib in terms of overall symptom relief. Of the eight patients who were able to identify the differences, seven had better relief with celecoxib and one with SR paracetamol. In 25 out of 41 [61%] patients, subsequent management was consistent with their trial results. Conclusions. N-of-1 trials may provide a rational and effective method to best choose drugs for individuals with osteoarthritis. SR paracetamol is more useful than celecoxib for most patients of whom management is uncertain.