Ethnicity Influences Phenotype and Outcomes in Inflammatory Bowel Disease: A Systematic Review and Meta-analysis of Population-based Studies.

BACKGROUND & AIMS: Inflammatory bowel diseases (IBDs) (Crohn's disease [CD], ulcerative colitis) are global diseases. Similarities and differences in disease presentation and outcomes across different geographic regions and ethnic groups have not been compared previously.

METHODS: We performed a systematic review and meta-analysis of population-based cohort studies examining the phenotype and outcome of IBD across ethnic groups categorized as Whites, Blacks, Hispanics, and Asians. Further stratification was performed by migration status (native or immigrant). Pooled proportions of disease location, behavior, medication, and surgery use were calculated by using a random-effects model and compared statistically.

RESULTS: Our final analysis included 198 unique studies reporting outcomes on 525,425 IBD patients (Caucasian, 65%; Asian, 30%; Hispanic, 2%; and Black, 1%). CD in Asians but not other ethnicities demonstrated a strong male predominance. Family history of IBD was infrequent in Asian patients. Both Black and Asian CD patients demonstrated perianal involvement more frequently. Surgery for both CD and UC was less common in Asians than Caucasians. Compared with native residents, a family history of IBD was reported more often among immigrant IBD patients, but no significant differences were noted in phenotype.

CONCLUSIONS: We demonstrate significant variation in the demographic distribution, familial predisposition, phenotype, and outcomes of IBD between Caucasians, Blacks, Hispanics, and Asians. There is need for further study to understand the biology behind this variation.