Increasing Incidence of Crohn's Disease with Familial Clustering in the Kingdom of Bahrain: A 25-Year Population-based Study.

BACKGROUND: The incidence of Crohn's disease has been increasing in developed countries; whether this trend has extended to countries in Middle East, especially in the Arab world, remains unclear. Our aim was to study the epidemiology, incidence, time trends and clustering of Crohn's disease within the population of the Kingdom of Bahrain.

METHODS: A retrospective case-cohort study was conducted on patients diagnosed with Crohn's disease at Bahrain Specialist Hospital between 1990 and 2015. The diagnosis was based on clinical, radiological, endoscopic, and histological examinations.

RESULTS: Five hundred twenty-two cases were eligible for analysis; 14.5% were below the age of 19 with a male-to-female ratio of 1.1:1. The overall incidence was 4.8/100,000 person-years and significantly increased from 5.5/100,000 person-years during the 1990's to 8.0/100,000 person-years during the last study period [incidence rate ratio (IRR) 0.32, 95% CI = 0.26-0.42]. This trend was persistent for adults, children, men and women. There were 129 patients with at least one family member diagnosed with Crohn's disease consisting of 40 families. Three clusters were identified based on first or second degree relationship of the family member. The mean interval for diagnosis between family members was significantly shorter between siblings than second degree relatives; (2.0 ± 1.2 years) versus (5.0 ± 2.8 years), respectively; (P = 0.04).

CONCLUSIONS: The incidence rate of Crohn's disease in Bahrain is comparable to the U.S.A and has increased for men and women in all age groups. Crohn's disease clusters were common among families and included up to 3 generations consistent with presence of a common source or common genetic factors.