Background:Recently, vital prognosis has been improved in patients with rheumatoid arthritis (RA)1. In elderly patients, it is difficult to establish a treatment strategy due to multi-morbidities and treatment-related risks. Since older age is a significant risk factor of serious infections, one of the primary concerns during treatment of RA, rheumatologists should always strike a balance between efficacy and safety of the immunosuppressive treatment. However, infection data under the targeted therapy (TT) in elderly patients is still limited to date.Objectives:To compare the risk of hospitalized infection (HI) under the TT among young, elderly, and older elderly patients with RA using the Japanese health insurance database.Methods:This retrospective longitudinal population-based study was conducted using claims data in Japan provided by Medical Data Vision Co., Ltd. We defined individuals as RA cases if they met all of the following: 1) having at least one ICD10 code (M05x, M06x except for M061, or M08x except for M081 and M082); 2) having at least one prescription of disease-modifying antirheumatic drugs (DMARDs) including methotrexate (MTX) and TT (biological DMARDs and Janus kinase inhibitors) between April 2008 and September 2018; and 3) 16 years old or older. We define the month patients met the above all criteria for the first time in this database as the index month. We excluded patients who were prescribed any DMARDs during the first 12 months from MTX users and those with prescription of any TT during the first 12 months from TT users (i.e., prevalent users). Among the study population, we divided patients into 3 groups according to their age at the index month; young group (16-64), elderly group (65-74), and older elderly group (>=75). The observation started from the index month and ended at 36 months later, the last month of the exposure of DMARDs, the month of loss of follow-up, or September 2019, whichever came first. HI was defined by ICD10 code with one prescription of predefined drugs for each infection during hospitalizations. Some of HIs were defined by ICD10 code alone.Results:In this study, 8269, 6454, 5745 patients with RA were included in the young, elderly, and older elderly groups, respectively. The incidence rate (IR) of HI (/100 patient-years [PY]) [95%CI] was 3.4 [3.1-3.7] in the young group, 5.8 [5.3-6.3] in the elderly group, and 12.0 [11.2-12.8] in the older elderly group. IR rate (IRR) of HI (reference: the young group) was 1.7 [1.5-1.9] in the elderly group and 3.6 [3.2-4.0] in the older elderly group. In the young group, the IRR of HI in TT users vs MTX users was significantly elevated (1.8 [1.5-2.1]), whereas, those of the elderly and the older elderly groups were significantly decreased (IRR 0.8 [0.7-0.9] for elderly; 0.6 [0.5-0.7] for older elderly). Concomitant use of immunosuppressive DMARDs or prednisolone >=10mg/day with TT became less frequent with aging.Conclusion:The elderly and older elderly patients had significantly higher risks of HI compared to the young. The risk of HI under the TT compared to MTX was decreased in the elderly patients, probably due to adjusting for treatment by attending physicians.References:[1]Arthritis Rheum 2014;66:786-93Acknowledgments:This work was supported by JSPS KAKENHI Grant Number 17K08963.Disclosure of Interests:Ryoko Sakai Grant/research support from: Tokyo Women’s Medical University (TWMU) has received unrestricted research grants forDivision of Epidemiology and Pharmacoepidemiology of Rheumatic Diseases from Ayumi Pharmaceutical Co. Ltd., Bristol Meyers Squib, Chugai Pharmaceutical Co. Ltd., Nippon Kayaku Co. Ltd., Taisho Toyama Pharmaceutical Co. Ltd., Mitsubishi Tanabe Pharma Corp., and with which TWMU paid the salary of R.S., Eiichi Tanaka Consultant of: ET has received lecture fees or consulting fees from Abbvie, Asahi Kasei pharma co., Bristol Myers Squibb, Chugai Pharmaceutical, Daiichi Sankyo Co., Eisai Pharmaceutical, Janssen Pharmaceutical K.K., Nippon Kayaku, Pfizer, Takeda Pharmaceutical, Taisho Toyama Pharmaceutical Co., and UCB Pharma., Speakers bureau: ET has received lecture fees or consulting fees from Abbvie, Asahi Kasei pharma co., Bristol Myers Squibb, Chugai Pharmaceutical, Daiichi Sankyo Co., Eisai Pharmaceutical, Janssen Pharmaceutical K.K., Nippon Kayaku, Pfizer, Takeda Pharmaceutical, Taisho Toyama Pharmaceutical Co., and UCB Pharma., masako majima: None declared, masayoshi harigai Grant/research support from: AbbVie Japan GK, Ayumi Pharmaceutical Co., Bristol Myers Squibb Co., Ltd., Eisai Co., Ltd., Mitsubishi Tanabe Pharma Co., Nippon Kayaku Co., Ltd., and Teijin Pharma Ltd. MH has received speaker’s fee from AbbVie Japan GK, Ayumi Pharmaceutical Co., Boehringer Ingelheim Japan, Inc., Bristol Myers Squibb Co., Ltd., Chugai Pharmaceutical Co., Ltd., Eisai Co., Ltd., Eli Lilly Japan K.K., GlaxoSmithKline K.K., Kissei Pharmaceutical Co., Ltd., Oxford Immuotec, Pfizer Japan Inc., and Teijin Pharma Ltd. MH is a consultant for AbbVie, Boehringer-ingelheim, Kissei Pharmaceutical Co., Ltd. and Teijin Pharma.
ICD10 Code Modification Corresponding to DPC System in Japan