ANTIBIOTIC DISPENSING PATTERNS IN INFLAMMATORY ARTHRITIS WITHIN ONE YEAR BEFORE AND AFTER DIAGNOSIS: A NATIONWIDE MATCHED-COHORT STUDY

Background: Systemic antibiotic exposure and subsequent changes in the composition of the human microbiota have been suggested to be a potential risk factor contributing to development of inflammatory arthritis (IA) including rheumatoid arthritis (RA), psoriatic arthritis (PsA), and ankylosing spondylitis/spondyloarthritis (AS/SpA). However, large-scale, nationwide studies on antibiotic use in the at-risk-period of IA are lacking. Objectives: To assess antibiotic dispensing patterns in IA within one year before and after diagnosis. Methods: Using prospectively collected data from Danish nationwide registries, we identified all individuals aged ≥18 years with a first-time diagnosis of IA from 2010 through 2018. For each IA patient, we randomly sampled ten persons from the background population (BP) matched on sex and birthdate (±6 months). We calculated the prevalence rate (n [%]) of any antibiotic (the number of individuals who had redeemed at least one prescription for any antibiotics divided by the total number of individuals still at risk at the beginning of the follow-up period) and the prevalence rate of the total antibiotic dispensing (the total number of redeemed prescriptions divided by the person time in the relevant period). Results: We identified 28,504 new-onset IA patients (RA, n=16,130; PsA, n=5,988; AS/SpA, n=6,386) and 285,040 age- and sex-matched individuals from the BP. The median age at diagnosis was 54 years (IQR 41-67), with RA patients being older (61 (IQR 41-67)), then PsA and AS/SpA patients (50 (IQR 40-60) and 41 (IQR 31-52), respectively). Both the prevalence rates of any antibiotic (Table 1) and the total antibiotic dispensing were higher during the one-year pre-diagnosis period of RA, PsA, and AS/SpA patients compared to BP individuals (prevalence rate ratios [PRR], 1.48 [1.46;1.51]; 1.67 [1.62;1.72]; 1.52 [1.47;1.56], respectively). For all IA subtypes, the total number of antibiotic dispensing increased markedly within 3 months before diagnosis followed by a decrease in individuals with RA and PsA, but not in AS/SpA, in the first 3 months after diagnosis (Figure 1). Although the prevalence rate of any antibiotic dispensing decreased for all IA subtypes in the year following the diagnosis (Table 1), total antibiotic dispensing remained constant in RA (PRR 0.99 [0.97;1.01]), decreased in PsA (0.91 [0.87;0.94]), and increased in AS/SpA (1.08 [1.04;1.12]) after diagnosis compared to before. Table 1. Prevalence of individuals redeeming one or more antibiotic prescriptions (%) within one year before and after diagnosis of RA, PsA, or AS/SpA, and BP stratified by sex, age, comorbidities, and treatment with biologics. RA PsA AS/SpA Age- and sex matched BP n = 16,130 n = 5,988 n = 6,386 n = 285,040 Before After Before After Before After Before After All, % 43.6 42.3 42.7 39.7 38.0 37.2 30.7 30.5 Sex, %  Male 38.8 37.3 35.8 31.9 32.6 31.1 24.5 24.4  Female 45.9 44.7 48.0 45.7 43.4 43.3 34.7 34.3 Age at diagnosis, %  18-40 44.0 39.6 43.5 40.0 36.0 35.4 29.8 28.8  41-60 39.7 38.1 40.5 38.0 37.1 35.8 28.2 27.7  61+ 46.2 46.0 46.3 43.0 47.8 47.8 34.0 34.5 Charlson Comorbidity Index at time of diagnosis, %  0 38.4 37.7 40.1 37.0 35.3 34.6 27.8 27.6  1-2 52.3 49.7 48.7 47.0 47.0 46.1 40.2 40.0  3+ 61.1 58.7 66.2 59.0 62.6 61.6 51.9 50.8 bDMARDs/tsDMARDs treatment after diagnosis, %  No treatment 43.4 42.0 42.1 39.5 38.2 37.0 30.8 30.6  Within ½ year 46.3 54.5 51.4 47.1 40.0 48.0 50.5 41.9  Between ½-1 year after 47.9 48.5 47.2 42.6 38.5 40.3 49.7 46.3 Figure 1. Temporal variations in total antibiotic dispensing per 1000 individuals, taking into account the amount of person time after index date, within one year before and after diagnosis of IA, RA, PsA, or AS/SpA, and BP. The dashed line designates time of diagnosis. Conclusion: Antibiotics are more frequently prescribed to individuals developing IA compared to the BP with a prominent increase in total antibiotic use in the last three months leading up to diagnosis. Incident IA diagnosis is associated with altered antibiotic dispensing patterns with marked differences among IA subgroups. These findings motivate more research into the underlying causes and potential consequences of antibiotic use in the year preceding an IA diagnosis. REFERENCES: NIL. Acknowledgements: NIL. Disclosure of Interests: None declared. DOI: 10.1136/annrheumdis-2024-eular.1283 Keywords: Epidemiology, Microbiome, Registries Citation: , volume 83, supplement 1, year 2024, page 422Session: Clinical Poster Tours: Immune checkpoint inhibitors and infection related arthritis (Poster Tours)

Epidemiology, Microbiome, Registries