Background: Though pharmacokinetic studies suggest accelerated biologic drug clearance with increasing body weight, evidence of obesity’s impact on clinical outcomes in biologic-treated patients with ulcerative colitis (UC) is inconsistent. Hence, we evaluated the impact of obesity on response to biologic therapy in UC patients.
Methods: In a single-center retrospective cohort study between 2011-16 of biologic-treated UC patients, we evaluated treatment response by baseline body mass index (BMI). Primary outcome was treatment failure (IBD-related surgery/hospitalization or treatment modification, including dose escalation, treatment discontinuation or addition of corticosteroids); secondary outcomes were IBD-related surgery/hospitalization and endoscopic remission. We conducted multivariate Cox proportional hazard analyses and logistic regression (for endoscopic remission) to evaluate the independent impact of BMI on clinical outcomes. Stratified analysis by weight-based regimens (infliximab) or fixed-dosing regimens (adalimumab, golimumab, vedolizumab, certolizumab pegol) was performed.
Results: We included 160 biologic-treated UC patients (50% males, 55% on infliximab) with median [IQR] age 36y [26-52] and BMI 24.3 [21.4-28.7] kg/m2. On multivariate analysis, each 1 kg/m2 increase in BMI was associated with 4% increase in the risk of treatment failure (adjusted hazard ratio, aHR 1.04 [95% confidence interval, CI 1.00-1.08], p=0.034), 8% increase in the risk of surgery/hospitalization (aHR 1.08 [95%CI 1.02-1.14], p=0.008), and 6% lower odds of achieving endoscopic remission (adjusted odds ratio, aOR 0.94 [95%CI 0.87-1.00], p=0.070). The effect on treatment failure was seen in patients on weight-based dosing regimens (aHR 1.05 [95%CI 1.00-1.10], p=0.05) or fixed-dose therapies (aHR 1.05 [95%CI 0.99-1.12], p=0.106).
Conclusion: BMI is independently associated with decreased response to biologic agents in UC patients, which may be independent of dosing regimen.
