Introduction: Over the past decade, the number of recognized cases of Inflammatory Bowel Disease (IBD) in non-Caucasians has significantly increased in the United States. However, the differences in IBD prevalence among patients of different races/ethnicities have not been well characterized. Our study examined the prevalence and demographic characteristics of IBD patients within a Northern California integrated healthcare delivery system.
Methods: We identified 8,064 adults age 18 years and older diagnosed with IBD between January 1 - December 31, 2014 in Kaiser Permanente Northern California (KPNC) with ICD-9 codes for ulcerative colitis (UC) and Crohn's disease (CD). The overall prevalence of IBD, UC, and CD by age, gender, and race ethnicity were calculated. We also calculated the prevalence of IBD, UC, and CD by gender and race/ethnicity in the elderly (65+) and younger adult (18-64) population. Patient self-reported race/ethnicity was obtained from the health plan administrative records.
Results: In 2014, the KPNC overall prevalence of IBD was higher in the elderly (65+) compared to younger adult (18-64) population (426 vs 230 per 100,000, p<0.01). IBD prevalence in females compared to males was 276 vs 255 per 100,000, p<0.01. Stratified by ethnicity, individuals of white race had the highest IBD prevalence compared to individuals of Asian, black, Hispanic, and other/multiple/unknown race/ethnicity (388 vs 131, 271, 182, 128 respectively per 100,000, p<0.01).
Conclusion: Our data demonstrate wide variation in the prevalence of IBD across ethnic groups within KPNC. IBD was most prevalent among individuals of white race, followed by black and then Hispanic race/ethnicity, and least prevalent among individuals of Asian race. There was a three-fold lower prevalence among Asians compared to those of white race. Further research is needed to better understand the etiology of this large variation.