Hypersensitivity Reactions with Allopurinol and Febuxostat in Adults 65 Years or Older: A Study Using the Medicare Claims Data

Jasvinder A. Singh¹ and John Cleveland², ¹Rheumatology, University of Alabama at Birmingham, Birmingham, AL, ²Rheumatology, University of Alabama at Birmingham (UAB), Birmingham, AL

Meeting: 2017 ACR/ARHP Annual Meeting

Date of first publication: September 18, 2017

Keywords: Adverse events, gout, hyperuricemia and uric acid

Session Information

Date: Tuesday, November 7, 2017

Session Title: Metabolic and Crystal Arthropathies Poster II

Session Type: ACR Poster Session C

Session Time: 9:00AM-11:00AM

Background/Purpose: Clinicians using allopurinol are always concerned about the risk of rare hypersensitivity reaction. Allopurinol and febuxostat are the two most common urate-lowering agents used for the treatment of hyperuricemia in gout. Population-based studies to estimate the risk of hypersensitivity reactions with allopurinol and febuxostat have not been done. Our objective was to describe the risk of hypersensitivity reactions with allopurinol and febuxostat.
Methods: We used the 5% Medicare Beneficiary sample (³65 years) from 2006-2012 to identify people with a new filled prescription for allopurinol or febuxostat or colchicine, with a baseline period of 365 days without either medication. We used Cox regression analyses to compare the hazard ratio (HR) of incident hypersensitivity reactions with allopurinol or febuxostat vs. colchicine use.

Results: Of the 68,230 new medication exposure episodes, 363 ended in a hypersensitivity reaction. Crude incidence rates of hypersensitivity reactions were as follows: allopurinol, 23.7; febuxostat, 30.7; and colchicine, 25.6 per 1,000 person-years. Incidence of hypersensitivity reactions was highest in the first 30 days of exposure to allopurinol or febuxostat, with a progressive reduction later. In multivariable-adjusted analyses, compared to colchicine, allopurinol, febuxostat and febuxostat + colchicine combination were associated with significantly higher hazard ratios of hypersensitivity reactions, 1.32 (95% CI, 1.10, 1.60) and 1.54 (95% CI, 1.12, 2.12) and 2.17 (95% CI, 1.18, 3.99), respectively. In multivariable-adjusted analyses limited to allopurinol users, compared to allopurinol start dose of <200 mg/day, allopurinol start dose of ³300 mg/day and diabetes were associated with significantly higher hazard of hypersensitivity reactions, 1.27 (95% CI, 1.12, 1.44), and 1.21 (95% CI, 1.00, 1.45).

Conclusion: In people 65 years or older, allopurinol and febuxostat increased the risk of hypersensitivity reactions. In allopurinol users, allopurinol start dose and diabetes increased this risk. Future studies need to examine as to why a higher start dose increases hypersensitivity risk.

Disclosure: J. A. Singh, Takeda and Savient, 2,Savient, Takeda, Regeneron, Merz, Iroko, Bioiberica, Crealta/Horizon and Allergan pharmaceuticals, WebMD, UBM LLC and the American College of Rheumatology., 5,JAS serves as the principal investigator for an investigator-initiated study funded by Horizon pharmaceuticals through a grant to DINORA, Inc., a 501 (c)(3) entity., 9,JAS is a member of the executive of OMERACT, an organization that develops outcome measures in rheumatology and receives arms-length funding from 36 companies., 9,JAS is the editor and the Director of the UAB Cochrane Musculoskeletal Group Satellite Center on Network Meta-analysis., 9,Jas is a member of the American College of Rheumatology's (ACR) Annual Meeting Planning Committee (AMPC); Chair of the ACR Meet-the-Professor, Workshop and Study Group Subcommittee., 9,a member of the Veterans Affairs Rheumatology Field Advisory Committee, 9; J. Cleveland, None.

To cite this abstract in AMA style:

Singh JA, Cleveland J. Hypersensitivity Reactions with Allopurinol and Febuxostat in Adults 65 Years or Older: A Study Using the Medicare Claims Data [abstract]. Arthritis Rheumatol. 2017; 69 (suppl 10). https://acrabstracts.org/abstract/hypersensitivity-reactions-with-allopurinol-and-febuxostat-in-adults-65-years-or-older-a-study-using-the-medicare-claims-data/. Accessed January 19, 2021.

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