“DO DISEASE MODIFYING ANTIRHEUMATIC DRUGS INFLUENCE THE FRACTURE RISK IN RHEUMATOID ARTHRITIS?” THE HUNT STUDY, NORWAY

I. Tronstad, M. Hoff, J. Horn, S. A. Vikjord, V. Videm, T. Nilsen, A. LanghammerNorwegian University of Science and Technology, HUNT Research Centre, Department of Public Health and Nursing, Trondheim, Norway Levanger Hospital, Department of Medicine and Rehabilitation, Levanger, Norway Norwegian University of Science and Technology, Department of Neuromedicin and Movement Science, Trondheim, Norway St. Olav’s University Hospital, Department of Rheumatology, Trondheim, Norway Levanger Hospital, Department of Obstetrics and Gynecology, Levanger, Norway Norwegian University of Science and Technology, Department of Clinical and Molecular Medicine, Trondheim, Norway St. Olav’s University Hospital, Department of Immunology and Transfusion Medicine, Trondheim, Norway Norwegian University of Science and Technology, Department of Public Health and Nursing, Trondheim, Norway St. Olav’s University Hospital, Clinic of Anaesthesia and Intensive Care, Trondheim, Norway Levanger Hospital, Nord-Trøndelag Hospital Trust, Levanger, Norway  Background Rheumatoid arthritis (RA) is associated with reduced bone mineral density and increased fracture risk. Bone sparing properties are reported for biological (b) disease-modifying antirheumatic drugs (DMARDs) (1), but previous studies have not found bDMARDs to reduce fracture risk [2]. Knowledge is sparce regarding fracture risk in individuals with RA using different types of DMARDs compared to the general population. Objectives To investigate the effect of RA on fracture risk, and examine if bDMARD treatment influences this association. Methods The Trøndelag Health Study (HUNT) is a population-based longitudinal study in central Norway. We included all participants who had attended at least one of the latest three HUNT surveys, using the first participation as baseline. RA status was obtained by linkage to the patient records at the regional hospital using International Classification of Disease codes (ICD9 and 10) for Major Osteoporotic Fractures (MOF), as well as further validation of medical records regarding date of RA diagnosis and use of DMARDs (divided into the following groups: never DMARDs, conventional synthetic(cs) DMARDs only, or ever bDMARDs). All RA diagnoses were validated according to American College of Rheumatology/ European League Against Rheumatism criteria[3]. RA status was registered at baseline and updated if RA was diagnosed later. Participants were followed until the first MOF, death, emigration, or end of follow-up on 21.10.2021. Cox regression was used to estimate hazard ratios (HR) for MOF in RA participants in general and by treatment group, compared to the people without RA. Confounders were identified using directed acyclic graphs (DAGs) and included sex, age at inclusion and smoking status at baseline. Results In total, 96,354 participants were included, 1,033 with RA (mean age 55.5 years, 65.8% women) and 95,321without RA (mean age 46.3 years, 53.0% women). Overall, 401 participants were diagnosed with RA before inclusion in HUNT and 632 during follow-up. Table 1. RA independent of treatment was associated with almost 50% increased risk of MOF compared to non-RA (HR 1.44). By treatment group, never DMARDs had highest risk of MOF, followed by csDMARDs. Treatment with bDMARDs was not associated with MOF. Incidence rates (IR) per 1000 person-years were higher in RA overall and in all DMARD treatment groups compared to non-RA. Participants MOF Unadjusted Adjusted n n IR 95% CI HR HR 95 % CI Non-RA 95,321 10,503 7.0 6.9-7.2 RA independent of treatment 1,033 221 18.0 15.8-20.5 2.35 1.44 1.25-1.65 RA treatment group Never DMARDs 57 17 33.4 20.7-53.7 4.42 2.05 1.28-3.31 csDMARDs only 727 175 20.5 17.7-23.8 2.68 1.50 1.29-1.75 Ever bDMARDs 230 27 8.8 6.0-12.8 1.13 1.03 0.70-1.50 Adjusted for age at inclusion, sex, and smoking status at baseline. CI: confidence interval. DMARDs group missing for 19 RA participants including 2 individuals with a MOF. Conclusion RA was associated with MOF. However, in RA individuals treated with bDMARDs, an association with MOF was not seen. This is an encouraging result and might be of importance when evaluation future treatment regiments in this patient group. References Chen J-F, Hsu C-Y, Yu S-F, Ko C-H, Chiu W-C, Lai H-M, et al. The impact of long-term biologics/target therapy on bone mineral density in rheumatoid arthritis: a propensity score-matched analysis. Rheumatology. 2020;59(9):2471-80. Shao F, Li HC, Wang MJ, Cui CM. Impact of biologic disease-modifying antirheumatic drugs on fracture risk in patients with rheumatoid arthritis: a systematic review and meta-analysis. Eur Rev Med Pharmacol Sci. 2021;25(9):3416-24. Videm V, Thomas R, Brown MA, Hoff M. Self-reported diagnosis of rheumatoid arthritis or ankylosing spondylitis has low accuracy: Data from the Nord-Trøndelag Health Study. J Rheumatol. 2017;44(8):1134-41. Acknowledgements The Trøndelag Health Study (HUNT) is a collaboration between HUNT Research Centre (Faculty of Medicine and Health Sciences, NTNU - Norwegian University of Science and Technology), Trøndelag County Council, Central Norway Regional Health Authority, and the Norwegian Institute of Public Health. We want to thank clinicians and other employees at Nord-Trøndelag Hospital Trust for their support and for contributing to data collection. Disclosure of Interests Ingebjørg Tronstad: None declared, Mari Hoff: None declared, Julie Horn: None declared, Sigrid Anna Vikjord: None declared, Vibeke Videm: None declared, Tom Nilsen: None declared, Arnulf Langhammer Speakers bureau: Paid as speaker by AstraZeneca, Boehringer Ingelheim, Glaxo-Smith-Klein, Consultant of: Paid consultant for Boehringer Ingelheim and AstraZeneca. Keywords: Epidemiology, bDMARD, Rheumatoid arthritis DOI: 10.1136/annrheumdis-2023-eular.2012Citation: , volume 82, supplement 1, year 2023, page 311Session: bDMARDS in RA 2.0: about the good and the bad (Poster Tours)