Prevalence and Impact of Obesity on Disease-Specific Outcomes in a Population-Based Cohort of Patients with Ulcerative Colitis.

Background and aims There remains a historical misconception that inflammatory bowel disease (IBD) patients are underweight. However, recent data suggests rates of obesity in IBD parallel those of the general population. The impact obesity has on the natural history of IBD is unclear. We aimed to determine obesity rates at the time of IBD diagnosis in a population-based cohort of ulcerative colitis (UC) patients. Methods Chart review was performed on patients diagnosed with UC from 1970-2010. Data were collected on demographics, body mass index (BMI), disease characteristics, plus IBD-specific hospitalizations, intestinal resection, and corticosteroid use. The proportion of patients who were obese at the time of their diagnosis was evaluated over time, and survival free of IBD-related complications was assessed using Kaplan-Meier survival analysis. Results 417 adults were diagnosed with UC from 1970-2010, 55.4% of whom were classified as either overweight (34.8%) or obese (20.6%). The prevalence of obesity increased 2-3 fold over the 40-year study period. Obese patients had a 72% increased risk of hospitalization (HR,1.72; 95% CI, 1.10 - 2.71; p=0.018) when compared to normal weight patients. Additionally, with each incremental increase in BMI by 1 kg/m2 , the risk of hospitalization increased by 5% (HR,1.05; 95% CI 1.01-1.08; p=0.008) and risk of corticosteroid use increased by 2.6% (HR,1.026; 95% CI 1.00-1.05; p=0.05). Conclusions The prevalence of obesity in the UC population is increasing, and may have negative prognostic implications, specifically regarding risk of future hospitalization and corticosteroid use. Additional prospective studies are necessary to more clearly define these associations.