Effects of Obesity on Response to Asthma Biologic Treatment: Longitudinal Data From the United Kingdom Severe Asthma Registry

Abstract

Background: Obesity is a common comorbidity associated with poor outcomes in severe asthma. Objective(s): We aimed to determine whether obesity is associated with an altered response to severe asthma biologic agents. Method(s): We analyzed data from the UK Severe Asthma Registry, a large UK-wide cohort of patients attending regional severe asthma services. We analyzed the change in clinical outcomes between baseline and first annual review visit by body mass index (BMI) category (healthy range 18.50-24.99], overweight 25.00-29.99], obese 30.00-39.99], and severely obese >=40]) and biologic treatment status. Result(s): The study cohort comprised 1956 patients, of whom 1477 (75.5%) commenced a biologic agent during the follow-up. Baseline Asthma Control Questionnaire-6 (ACQ-6) scores and rates of exacerbations, emergency department attendances, and hospital admissions were higher with increasing BMI category. Biologic treatment was associated with significant additional improvement in ACQ-6, compared with patients not receiving biologics, in overweight, obese, and severely obese patients. However, the ACQ-6 score after biologic treatment remained significantly different across BMI categories, with the mean score being 1.3 in the healthy weight group and 2.8 in the severely obese group (P < .001). Biologic treatment was associated with significant additional reductions in exacerbation rates in all BMI groups except for the severely obese group. Conclusion(s): Asthma biologic agents appear to have important clinical benefits across the spectrum of BMI. However, because patients with obesity start at a worse baseline with respect to symptoms and exacerbations, they are still more likely to remain uncontrolled after treatment. Copyright © 2025 The Authors