Individual responses to topical ibuprofen gel or capsaicin cream for painful knee osteoarthritis: a series of n-of-1 trials

Persson, Monica S.M.; Stocks, Joanne; Sarmanova, Aliya; Fernandes, Gwen; Walsh, David A.; Doherty, Michael; Zhang, Weiya

Abstract

OBJECTIVES: To determine individual responses to ibuprofen gel or capsaicin cream for painful, radiographic knee OA using a series of n-of-1 trials. METHODS: Twenty-two participants were allocated 5% ibuprofen gel (A) and 0.025% capsaicin cream (B) in random sequence (AB or BA). Patients underwent up to 3 treatment cycles, each comprising one treatment for 4 weeks, an individualized washout period (maximum 4 weeks), then the other treatment for 4 weeks. Differential (ibuprofen or capsaicin) response was defined when change-from-baseline pain intensity scores (0-10 NRS) differed by ≥1 between treatments in ≥2 cycles within a participant. RESULTS: A total of 104 treatment periods were aggregated. Mean pain reduction was 1.2 (95% CI: 0.5, 1.8) on ibuprofen and 1.6 (95% CI: 0.9, 2.4) on capsaicin (P = 0.221). Of 22 participants, 4 (18%) had a greater response to ibuprofen, 9 (41%) to capsaicin, 4 (18%) had similar responses, and 5 (23%) were undetermined. CONCLUSION: Irrespective of equal efficacy overall, 59% of people displayed a greater response to one treatment over the other. Patients who do not benefit from one type of topical treatment should be offered to try another, which may be more effective. N-of-1 trials are useful to identify individual response to treatment. CLINICAL TRIAL REGISTRATION: https://clinicaltrials.gov, NCT03146689.

Citation

Persson, M. S., Stocks, J., Sarmanova, A., Fernandes, G., Walsh, D. A., Doherty, M., & Zhang, W. (2021). Individual responses to topical ibuprofen gel or capsaicin cream for painful knee osteoarthritis: a series of n-of-1 trials. Rheumatology, 60(5), 2231-2237. https://doi.org/10.1093/rheumatology/keaa561

• Journal Article Type: Article
• Acceptance Date: Jul 31, 2020
• Online Publication Date: Nov 16, 2020
• Publication Date: May 14, 2021
• Deposit Date: Aug 4, 2020
• Publicly Available Date: Nov 17, 2021
• Journal: Rheumatology
• Electronic ISSN: 1462-0324
• Publisher: Oxford University Press
• Peer Reviewed: Peer Reviewed
• Volume: 60
• Issue: 5
• Pages: 2231-2237
• DOI: https://doi.org/10.1093/rheumatology/keaa561
• Keywords: topical NSAID, capsaicin, osteoarthritis, n-of-1, response
• Public URL: https://nottingham-repository.worktribe.com/output/4811271
• Publisher URL: https://academic.oup.com/rheumatology/article-abstract/60/5/2231/5983716
• Additional Information: This is a pre-copyedited, author-produced version of an article accepted for publication in Rheumatology following peer review. The version of record Monica S M Persson, Joanne Stocks, Aliya Sarmanova, Gwen Fernandes, David A Walsh, Michael Doherty, Weiya Zhang, Individual responses to topical ibuprofen gel or capsaicin cream for painful knee osteoarthritis: a series of n-of-1 trials, Rheumatology, , keaa561 is available online at: https://doi.org/10.1093/rheumatology/keaa561.