Is obesity a risk factor for Crohn's disease?

BACKGROUND

Obesity is associated with a proinflammatory state.

AIM

To determine whether obesity at diagnosis is a risk factor for Crohn's disease vs. ulcerative colitis and also vs. community controls and whether there is a U-shaped relationship between body mass index at diagnosis and risk of Crohn's disease versus ulcerative colitis.

METHODS

A total of 524 consecutive inflammatory bowel disease patients attending gastroenterology clinics were administered a questionnaire inquiring about weight at diagnosis and height as well as other risk factors for inflammatory bowel disease. An opportunistic control group of 480 community controls aged 50-70 were randomly selected from the registers of four local general practices as part of another study.

RESULTS

Obesity at diagnosis was more common in subjects with Crohn's disease versus ulcerative colitis odds ratio 2.02 (1.18-3.43) p = 0.0096 and also Crohn's disease versus community controls in the 50-70 year age group (odds ratio 3.22 (1.59-6.52) p = 0.001). There was evidence of a 'dose response' with increasing degrees of obesity associated with increased risk. Low BMI at diagnosis was also associated with risk of Crohn's disease versus ulcerative colitis. A U-shaped relationship between BMI and risk of Crohn's was supported by the strong inverse association of BMI at diagnosis (p = 0.0001) and positive association of BMI at diagnosis squared (p = 0.0002) when they were fitted together into the model.

CONCLUSIONS

Obesity may play a role in the pathogenesis of Crohn's disease and it may be that obesity-related enteropathy is a distinct entity or a sub-type of Crohn's disease.