Background/Purpose: Reactive arthritis (ReA) is a sterile arthritis occurring in a genetically predisposed individual, secondary to an extra-articular infection, usually of the gastrointestinal or genitourinary tract. Intravesical instillation of Bacillus Calmette-Guerin (iBCG) is used as an effective immunotherapy of bladder cancer. Despite of the clinical efficacy, ReA could develop as adverse event and the frequencies are known as about 0.5 to 1 % in Western countries.To assess the trend of frequency, HLA phenotype and outcome of iBCG-induced ReA in Japanese patients with bladder cancer following iBCG therapy.

Methods: The clinical findings of Japanese patients who received iBCG (n = 555) for bladder cancer from March 1997 to February 2017 were retrospectively assessed, with specific attention to frequency and HLA phenotype of ReA. Because of the change of using iBCG dosage, iBCG-induced ReA patients diagnosed from 1997 to 2007 were also compared with ReA from 2007 to 2017 and the trend of frequency was examined. Furthermore, we assessed outcomes of iBCG-induced ReA patients over the 20 years.

Results: Patients’ mean age was 72 ± 10 years and male/female ratio was 438/117. Of the 555 cases, ReA was revealed in 11 (2.0%). 9.1% of 11 ReA patients had HLA-B27. Although the protocol of iBCG therapy was not statistically different over the 20 years, but a half dose of iBCG was used in 2007 to 2017 more than in 1997 to 2007. Despite the increase of half dose using of iBCG in 2007 to 2017, the overall frequency of iBCG-induced ReA was not significantly different between from 1997 to 2007 and from 2007 to 2017 (2.1% and 1.9%, respectively). Finally, as outcomes, all iBCG-induced ReA patientsdid not progress to chronic peripheral arthritis type and axial SpA, even if with sacroiliitis.

Conclusion: The 2.0% iBCG-induced ReA frequency in Japanese patients exceeds that in Western countries. Despite iBCG dosage was different, the trend of frequency has been stable, which suggested possible dose-independent development. Furthermore, all iBCG-induced ReA, even if revealing sacroiliitis, did not progress to chronic peripheral arthritis type and SpA over the last 20 years.

ACR Meeting Abstracts - https://acrabstracts.org/abstract/trend-of-frequency-and-outcome-of-reactive-arthritis-in-japanese-patients-with-bladder-cancer-following-intravesical-bcg-therapy-over-the-last-20-years/