African American Ethnicity Associated with Decreased Odds of Inflammatory Bowel Disease: Results of a Nationwide Analysis

Abstract

Introduction: Inflammatory bowel disease (IBD) affects all ethnicities worldwide, with the highest prevalence in North America and Europe. While several studies have suggested a higher occurrence of IBD in Caucasians, most prior studies were performed on Caucasian-predominant populations. The aim of this study was to assess the occurrence of IBD in African American (AA) patients in the US. Methods: This was a case-control study using the National Inpatient Sample 2014, a US inpatient database. All patients with ICD-9 CM codes corresponding to IBD were included. There were no exclusion criteria. AA were identified within the database from the ethnic categories. Population estimates were obtained from the U.S. National Census Bureau. The primary outcome was the occurrence and odds of IBD in the AA population compared to other ethnicities. Secondary outcomes were inpatient mortality, morbidity, as measured by shock, ICU stay, multi-organ failure and colectomy; resource utilization, including use of abdominal CT and colonoscopy; length of hospital stay, hospitalization charges and costs. Propensity score matching was used to create a 1:1 matching population, and was regressed against gender, age and Charlson Comorbidity Index. Multivariate regression analyses were used to adjust for income in patients' zip code, hospital region, location, size and teaching status. Results: 32,665 cases of IBD were identified in the AA population and propensity-matched. The mean patient age was 44 years, 58% were female. The prevalence of IBD in admitted AA was 80/100,000 persons (330/100,000 admissions), compared to 100/100,000 persons (1,147/100,000 admissions) of other ethnicities. Adjusting for confounders, admitted AA patients displayed adjusted matched odds of 0.60 (p<0.01) of having IBD compared to other admitted ethnicities. All outcomes are in Table 1. For secondary outcomes, AA displayed higher propensity-matched odds of CT abdomen (aOR:2.20, p<0.01) and multi-organ failure (aOR:1.24, p<0.01), but lower odds of TPN (aOR:0.80, p=0.02). All ethnicities did not differ in odds of mortality, shock, ICU stay or abdominal ultrasound. Conclusion: The national prevalence of IBD is lower in the AA population, which corroborates findings of prior smaller studies. Although, the odds of AA patients having IBD are markedly decreased compared to other ethnicities, AA displayed higher odds of CT abdomen, colonoscopy and multi-organ failure, potentially reflecting a worse disease course.729 Figure 1. - Adjusted means and odds ratios for evaluated parameters in African Americans compared to other ethnicities with inflammatory bowel disease.