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 suggest rates of obesity in IBD parallel to 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 over 1970-2010. Data were collected on demographics, body mass index [BMI], disease characteristics, IBD-specific hospitalisations, 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: A total of 417 adults were diagnosed with UC over 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 hospitalisation (hazard ratio [HR],1.72; 95% confidence interval [CI], 1.10-2.71; p = 0.018) when compared with normal weight patients. Additionally, with each incremental increase in BMI by 1 kg/m2, the risk of hospitalisation 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 hospitalisation and corticosteroid use. Additional prospective studies are necessary to more clearly define these associations.