Obesity and Inflammatory Bowel Disease: Outcomes of Patients in a Pro-inflammatory State on Biologic Therapy for Crohnʼs Disease and Ulcerative Colitis

Abstract

Introduction: The prevalence of both inflammatory bowel disease (IBD) and obesity are increasing worldwide, and it is estimated that 15-40% of patients with IBD are obese. Adipose tissue is known to cause release of cytokines and tumor necrosis factor (TNF)-alpha implicated in both luminal and systemic inflammatory responses in patients with IBD. Currently, the effect of obesity on IBD and clinical outcomes remains under-described. Our aims are to characterize a cohort of patients with IBD on biologic therapy and to examine the effect of obesity (BMI > 30) on rates of liver function test abnormalities, development of malignancy, infections, and mortality. Methods: This is a retrospective analysis conducted at a tertiary care, academic-affiliated medical center with a center for inflammatory bowel disease. Patients with Crohn's disease or ulcerative colitis and on biologic therapy were identified using ICD-9 and 10 codes. Baseline anthropologic, serologic, and clinical data was obtained. Results: In a cohort of 72 patients, the mean age was 48, and 40% were female. Mean BMI was 28kg/m2. 59 patients (82%) had Crohn's disease. The mean years of disease duration was 17, and 20 patients (53%) also carried a diagnosis of NAFLD/NASH. 52 patients in the cohort were on biologic therapy, with 24 (46%) on infliximab, 18 (35%) adalimumab, 4 (8%) ustekinumab, 4 (8%) certolizumab pegol, and 2 (4%) vedolizumab. A higher proportion of obese vs non-obese patients on biologics had liver function test (LFT) abnormalities (77% vs 38%, P=0.019). There was no difference in peak alanine aminotransferase (ALT) levels between the two groups, 78 U vs 73 U, P=0.784 (ref range ALT 0-40 U). No difference was noted in the proportion of obese vs non-obese patients in developing malignancy (3% vs 0%, P=0.505), infection (23% vs 8%, P=0.226), and there were no deaths in either group. A higher proportion of patients that were obese were on infliximab (77% vs 30%, P=0.057). All obese patients were on an anti-TNF (infliximab or adalimumab). No mortality was noted in either group. Conclusion: Obese patients have higher risk for LFT abnormalities while on biologic therapy. This may be due to pre-existing hepatic inflammation from fatty liver disease. Moreover, obese patients did not develop more complications when on biologic therapy (e.g. malignancy or infection) compared to nonobese patients. Nonetheless, lifestyle modification and weight loss should be encouraged and be a part of routine IBD care in this population.