Obesity is not associated with an increased risk of serious infections in biologic-treated patients with inflammatory bowel diseases

INTRODUCTION: Obesity has been associated with adverse disease-related outcomes and inferior treatment response to biologic agents in patients with inflammatory bowel diseases (IBDs), but its impact on the risk of treatment-related complications is unknown. We performed a cohort study examining the association between obesity and risk of serious infections in biologic-treated patients with IBD. METHODS: Using an administrative claims database, in a cohort of biologic-treated patients with IBD between 2014 and 2018 with follow-up 1 year before and after treatment initiation, we compared the risk of serious infections (infections requiring hospitalization) between obese vs nonobese patients (based on validated administrative claims) using Cox proportional hazard analysis. RESULTS: We included 5,987 biologic-treated patients with IBD (4,881 on tumor necrosis factor-a antagonists and 1,106 on vedolizumab), of whom 524 (8.8%) were classified as obese. Of the 7,115 person-year follow-up, 520 patients developed serious infection. Risk of serious infection was comparable in obese vs nonobese patients (8.8% vs 8.5%; unadjusted hazard ratio, 1.15; 95% confidence interval, 0.86-1.54). After adjusting for age, comorbidities, disease characteristics, health care utilization, use of corticosteroids, immunomodulators, and opiates, obesity was not associated with an increased risk of serious infection (adjusted hazard ratio, 0.74 [95% confidence interval, 0.55-1.01]). Similar results were seen on stratified analysis by disease phenotype (Crohn's disease and ulcerative colitis) and index biologic therapy (tumor necrosis factor-a antagonists and vedolizumab). DISCUSSION: After adjusting for comorbid conditions and disease characteristics, obesity is not independently associated with an increased risk of serious infections in biologic-treated patients with IBD.