P450 Influence of radon levels at home in the clinical course of inflammatory bowel disease incident patients

Abstract

Abstract Background Inflammatory Bowel Diseases (IBD) are a group of pathologies of unknown etiology associated with some environmental factors, only partially identified. The role of indoor radon, a radioactive gas, has not been formally studied and it might play a role on the evolution of the disease. The aim of this study is to analyze if residential radon exposure is associated with the evolution and development of flares or hospitalizations of IBD new diagnosed patients in a radon-prone area. Methods An observational prospective study was developed between June 2020 and September 2023, including incident cases with IBD that had been living at least 5 years in the same dwelling, those with a change of address in the last 5 years prior to diagnosis were excluded. All patients were followed-up through one year to assess the evolution of the disease. Hospitalizations related with the disease during the period, and number and severity of flares (measured by Partial Mayo Score and Harvey- Bradshaw) were collected. Radon levels were measured over three months in the participants’ home. Each individual was provided with a residential radon meter (a RSKS trace detector), given and read by the Galician Radon Laboratory, a certified radon laboratory. Radon concentrations were categorized into three groups, 0-99 Bq/m3, 100-299 Bq/m3 and >299 Bq/m3. Results are expressed as Odds Ratios with their 95%CI obtained through logistic regression. Results 136 patients with IBD (78 ulcerative colitis, 52 Crohn’s disease and 6 unclassified colitis) were included and prospectively followed, with a median age of 52 years old (IQR 40 – 59). 50% were females. There were no statistically significant differences in radon levels, taking levels of 0-99 Bq/m3 as reference, between patients hospitalized compared with non-hospitalized (OR 0.8 95%CI 0.3-2.1 for 100-299 Bq/m3, OR 1.7 95%CI 0.6-5.0 for >299 Bq/m3) nor in patients with a flare compared with patients without flares during the follow-up year (OR 0.4 95%CI 0.0-4.5 for 100-299 Bq/m3, OR 5.4 95%CI 0.8-34.3 for >299 Bq/m3). Radon levels were not associated with the number of flares either (OR 0.6 95%CI 0.3-1.7 for 100-299 Bq/m3, OR 1.5 95%CI 0.5-4.5 for >299 Bq/m3). Results are shown in table 1. Stratifying by type of IBD, results do not vary. For Crohn’s disease, OR for flare are 2.5 (95%CI 0.4-16.1) and 4.1 (95%CI 0.6-27.9), and for hospitalization 1 and 6.5 (OR95% (0.2-205-2). For ulcerative colitis, OR for flare are 0.6 (95%CI 0.2-1.8) and 1.8 (95%CI 0.4-7.8) and for hospitalization 0.9 (95%CI 0.1-17.1) and 9.3 (95%CI 0.6-134.0). Conclusion Indoor radon concentration seems to be not associated with an initial worst evolution of IBD patients in terms of hospitalizations or flares.