Epidemiology of inflammatory bowel disease among an indigent multi-ethnic population in the United States

Background: Environmental factors, including socioeconomic status, may affect inflammatory bowel disease (IBD). There is a paucity of data on the epidemiology of IBD among patients of low socioeconomic status. Aim: To examine the epidemiologic features of IBD among African-American, Hispanic, and Caucasian patients from a county hospital, where the majority of the patients are socioeconomically disadvantaged. Methods: A retrospective study was conducted on a cohort of patients diagnosed with IBD based on clinical, radiologic, endoscopic, and histological data. We reviewed charts of adults aged 20-70 years diagnosed with IBD between 2000 and 2006. Demographic data, disease subtype, and phenotypic features of IBD were recorded based on the Montreal Classification. The data were analyzed using the chi-square, Fisher exact, Wilcoxon rank-sum, and Student's t-tests. Results: The study cohort included 273 patients, with 54% female, 30% Caucasian, 44% African-American, and 26% Hispanic. Over half (54%) of the patients had Crohn's disease (CD), and 46% had ulcerative colitis (UC). The mean age at diagnosis was 40 ± 14 years with no significant difference between CD and UC (age 43 ± 13 versus 44.5 ± 14, respectively; P = 0.5). Females were diagnosed at a significantly later age than males (46 ± 13 years versus 40 ± 13, respectively; P = 0.001). This trend remained significant for females with CD and UC, and across each racial/ethnic group. Hispanic patients were diagnosed with UC more often than Caucasian patients (64% versus 34%; odds ratio [OR] 3.5; 95% confidence interval [CI]: 1.8-6.5, P = 0.0003) or African-Americans (64% versus 43%; OR 2.3; 95% CI: 1.3-4.3, P = 0.005). Among the 147 patients with CD, 54% had fistulizing and/or stricturing disease. The prevalence of fistulizing, stricturing, and inflammatory CD was similar across all age, gender, and racial/ ethnic groups. Conclusions: Within an indigent population, UC was diagnosed more often in Hispanics than CD. Females were diagnosed at a significantly older age than males across all racial/ethnic groups. There was no difference in the CD phenotypes between the three ethnic groups. Understanding the epidemiology of IBD will require examination of the interactions between gender, race/ ethnicity, and environmental factors.