Irritable Bowel Syndrome and Allergic Diseases: A Nationwide Study of 1.5 Million Adolescents

BACKGROUND: Recent evidence suggests an increased prevalence of irritable bowel syndrome (IBS) among individuals with allergic diseases, and several biological mechanisms have been proposed. This study aims to investigate the association between IBS and allergic diseases in a large nationwide cohort of adolescents. METHODS: This cross-sectional nationwide study included Israeli adolescents aged 16-20 years who underwent medical assessment before military service. The military database was used to identify individuals with allergic diseases (asthma, allergic rhinitis, atopic dermatitis, or ocular atopic disease) and IBS between 1998 and 2018. Logistic regression models adjusted for sociodemographic factors were applied. RESULTS: Of the 1,538,864 adolescents (42% women; mean age, 17.2 ± 0.5 years) included in the study, 189,806 (12.3%) were diagnosed with allergic diseases and 8,134 (0.5%) with IBS. Overall, 25.4% of adolescents with IBS had at least one concurrent allergic disease. The prevalence of IBS among adolescents with allergic diseases was 1.1%, corresponding to an adjusted OR of 2.2 (95% CI 2.1-2.4). This association remained consistent across socioeconomic groups and across all allergic diseases examined. CONCLUSION: Allergic diseases in adolescents are associated with higher rates of concurrent IBS. These findings strengthen existing epidemiological evidence linking IBS and allergic diseases in adolescents and warrant further mechanistic and longitudinal studies.