P1106 Is indoor radon associated with new diagnosis of inflammatory bowel disease 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 onset of the disease. The aim of this study is to analyze the role of individual residential radon exposure on the incidence of IBD in a radon-prone area also characterized as a high incidence IBD region. Methods A case-control study was developed in the health area of Santiago de Compostela (Galicia, Spain) between June 2020 and September 2023, including incident cases with IBD. Controls were selected trough a frequency matching based on sex and age and without IBD. All participants had to be 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. Endoscopic index, imaging techniques and analytic parameters were collected. Radon levels measured over three months in the participants’ home were compared between cases and controls, and between the different types of IBD. 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. Procedure is summarized in Figure 1. 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 178 incident cases and 178 controls (102 ulcerative colitis, 70 Crohn’s disease and 6 unclassified colitis) were included, with a median age of 51 years old (IQR 40 – 59.5). 51.7% were females. Median radon levels of IBD patients´ homes were 144.5 (IQR 83 – 260) and median radon levels of controls´ homes were 189.5 (IQR 112 – 292.5) (figure 1). Adjusting by age and sex, high radon levels showed a negative association for the development of IBD (taking levels of 0-99 Bq/m3 as reference, OR 100-299 Bq/m3 is 0.5 (95%CI 0.3-0.8), and OR >299 Bq/m3 is 0.5 (95%CI 0.3-0.9). Results are shown in table 1. Analyzing women and men separately, there are no statistically significant differences (p>0.05 in each group). Taking into account the different types of IBD, radon levels show the same negative association but without statistical association. Conclusion High radon levels might be a protective factor for developing IBD overall and its most common types, Crohn’s disease and ulcerative colitis. Further studies in other areas with lower radon concentrations will be necessary to corroborate whether it influences the incidence of IBD.