Temporal trends in obesity and its prognostic impact in Korean patients with inflammatory bowel disease.

Background: To assess the changes in body mass index (BMI) among Korean patients with inflammatory bowel disease (IBD) over a 14-year period and to explore how BMI at diagnosis impacts prognosis.

Methods: We retrospectively collected BMI and laboratory data from patients with IBD who visited the Asan Medical Center between 2008 and 2021 (Cohort 1). Clinical outcomes, including intestinal resection and medication use, were analyzed in patients with a recorded BMI at diagnosis who were followed up in a prospectively maintained cohort (Cohort 2).

Results: Among 11,216 IBD patients (Cohort 1), the median BMI increased over the study period, and the disparity in the prevalence of obese individuals (BMI ≥ 25 kg/m²) between those with IBD and the general population narrowed. Serum glucose and lipid profiles showed an upward trend during the study period. In patients with recorded BMI at the time of diagnosis (Cohort 2), the odds of intestinal resection and the use of biologics/small molecules were comparable or even lower in Crohn's disease (CD) and ulcerative colitis patients who were obese compared to patients with a normal BMI. Obesity (≥ 25 kg/m²) was inversely associated with the risk of thiopurine use in CD patients (adjusted hazard ratio: 0.61, 95% confidence interval: 0.48-0.78, p < 0.001).

Conclusions: During a 14-year period, Korean IBD patients showed increasing trends in the prevalence of obese individuals and metabolic syndrome-associated laboratory results. CD patients with high BMI at diagnosis exhibited a similar or lower likelihood of undergoing intestinal resection and medication use compared to those with a normal BMI.