Overweight and obesity in chronic spontaneous urticaria – A retrospective cohort study

Objectives: This study aims to assess the prevalence of excess weight in chronic spontaneous urticaria (CSU) patients and its associations with treatment response and disease course. CSU affects 0.5-1.5% of the population and many patients remain uncontrolled despite the available treatments. Patient-reported outcomes (PROs) are used to monitor disease activity and treatment response. Obesity is a highly prevalent condition that shares inflammatory pathways with CSU; however, links between them remain poorly understood. Methods: This retrospective cohort study was conducted at the Dermatology Department of the Coimbra University Hospital and included adults (≥ 18 years) with CSU diagnosis. Collected data included demographics, body mass index (BMI) at CSU onset and at first urticaria consultation, age at onset, disease duration, type of treatment, treatment duration, and response. Variables were compared across BMI categories (normal weight, overweight, and obese), with p < 0.05 considered significant. Treatment response, the primary outcome, was defined as an ordinal variable using validated PROs cut-offs (Urticaria Activity Score over 7 days, Urticaria Control Test, and Dermatology Life Quality Index). Ordinal logistic regression analyses were performed. Results: The study included 90 patients (83.3% female), with a median age of 48 years. Mean BMI at onset was 27.80 ± 5.24 kg/m2 (72.2% of patients with excess weight) and 28.10 ± 5.41 kg/m2 at first consultation (68.9% excess weight). Treatment response differed significantly across BMI categories (p = 0.007), with complete response (CR) decreasing from 46.4% (normal weight group) to 6.5% (obese group). In ordinal logistic regression models, obesity was associated with worse treatment outcomes (p < 0.001, odds ratio = 7.63). In adjusted models, other variables showed no association. Age at CSU onset differed between normal weight and overweight patients (Bonferroni p = 0.025), with overweight patients presenting later disease onset. Disease duration, type of treatment, and duration did not differ across BMI. Conclusion: The patients’ profile was consistent with previous CSU literature, reinforcing the high BMI prevalence. This study suggests that obesity is associated with a lower probability of achieving CR, emerging as an independent predictor of worse treatment outcomes. The findings support considering weight management as part of the CSU approach, warranting prospective studies.