Influence of urban/rural and coastal/inland environment on the phenotype and clinical course of inflammatory bowel disease patients from Sri Lanka: a cross-sectional study

Abstract

INTRODUCTION & OBJECTIVES: Rural/urban and coastal/inland environmental influences on inflammatory bowel disease (IBD) is poorly studied. We investigated such environmental influences on IBD. METHODS: Patients with histologically proven IBD [ulcerative colitis (UC), Crohn disease (CD)] with a permanent residence and regular follow up, were included. Urban areas (UA) were defined as those administered by Municipal and Urban councils. Coastal areas (CA) were defined as areas with elevation <30 meters above sea level. Patients in different groups were compared with regard to phenotype of IBD [sex, age at diagnosis, Montreal subgroups, severity, extraintestinal manifestation (EIM) at diagnosis, and highest therapy during follow-up]. Fisher’s exact test was used to compare categorical variables. RESULTS: A total of 387 patients were included [UC-251 (64.8%), males-122 (48.6%), median followup (IQR)-22.5 (2-59) months; CD-136 (35.2%), males-65 (47.8%), median follow-up (IQR)- 63.0 (23-115) months; urban/rural distribution: UC-1.7:1, CD-1.5:1; coastal/inland distribution: both UC and CD-0.7:1]. Urban/rural or coastal/inland location did not affect the distribution of type of IBD, gender, age at diagnosis or presence of EIM. UC patients from rural areas had extensive disease (E3) (42.4% vs 24.5%, p=0.029) and used long term immunomodulator drugs more frequently (60.2% vs 47.3%; P=0.006) than UA patients. CD patients living in CA had more frequent ileo-colonic disease (L3) compared to inland patients (53.2% vs 38.0%, p=0.016). Patients with both UC and CD from inland areas needed immunomodulators or anti-TNF more frequently than coastal patients (56.7% vs 44.9%, p=0.026 and 82.1% vs 69.9%, p=0.023). CONCLUSION: IBD was more common among patients from inland, UA. Urban/rural or coastal/inland location did not affect gender, age at diagnosis or presence of EIM. However, UC patients from rural areas and CD patients from inland areas had more severe disease.