The effect of body weight on the severity and clinical course of ulcerative colitis

Obesity is a risk factor for inflammatory diseases such as nonalcoholic steatohepatitis, pancreatitis, and Crohn's disease. The effect of being overweight or obese on the severity and clinical course of ulcerative colitis (UC) was assessed in a retrospective analysis of data from 2000-2006.

Two hundred and two consecutive UC patients were categorized according to body mass index (BMI). Patient and disease characteristics were compared between BMI categories using chi-square or Kruskal-Wallis tests. The percentage of patients with active UC, complications, steroid therapy, or immunosuppressive therapy was calculated for each group, and matched pair analyses were performed.

Ten patients (5%) were underweight, 111 (55%) were normal weight, 54 (26.7%) were overweight, and 27 (13.4%) were obese. Pancolitis was inversely related to weight. BMI was also inversely correlated to disease severity, with a significantly smaller proportion of years with chronic active disease among overweight subjects versus normal-weight subjects (17.6 versus 23.9%, p = 0.05). More overweight than normal-weight patients had no chronic active disease in any year (66 versus 49%, p = 0.06), and the proportion of years with disease complications was higher in normal weight than in overweight subjects (1.8 versus 0.4%, p = 0.08). Disease activity during 2000-2006 was higher for underweight versus normal-weight patients, and only 20% of underweight subjects had no hospital admission compared to 80% of normal-weight patients (p = 0.07).

This first study to explore the influence of obesity on UC showed that high BMI had rather a favorable effect on the prognosis, whereas low BMI pointed to a more severe course of the disease.