Obesity Associated With Later CSU Onset, Reduced Therapy Response

A new report suggests patients with obesity and chronic spontaneous urticaria (CSU) tend to be older when diagnosed with the latter condition, and are also less likely to respond to omalizumab (Xolair), though it is not clear the association is causal.

Those were among the findings of a new report appearing in the World Allergy Organization Journal that examined characteristics of patients with 3 subtypes of CSU, and also compared those subtypes with treatment response.¹

CSU itself is marked by the appearance of pruritic wheals that persist for more than 6 weeks without an identifiable trigger. Approximately 4 in 10 patients with CSU also have angioedema, and approximately 1 in 10 patients has angioedema without wheals, the authors noted.

Antihistamines are typically the first-line therapy for CSU, followed by omalizumab, and cyclosporine if antihistamines do not work. However, the investigators added that disease-modifying therapies hold the potential to further improve outcomes for people with the disease.²

“Identifying potential biomarkers that can predict disease progression at the onset is crucial, as this would allow for early determination of which patients could benefit from more advanced treatments,” the authors wrote.

The investigators decided to analyze patient characteristics through the lens of CSU subtypes. They recruited 50 patients with isolated urticaria and no angioedema, 86 patients with both urticaria and angioedema, and 43 patients with isolated angioedema. They used several tools to assess the participants: the Visual Analogue Scale for the Worst Attack (VAS-WA), the Visual Analogue Scale for Angioedema Control (VAS-AEC), the Angioedema Control Test (AECT), the Urticaria Control Test (UCT), and the Angioedema Quality of Life (AEQoL) tool.

A number of associations were seen in the study. Patients with isolated angioedema—which is also called chronic histaminergic angioedema (CHA)—tended to have a higher age of onset than patients with both urticaria and angioedema (P < .001). People with CHA also had higher rates of oropharyngeal angioedema (P = .022), though patients with both urticaria and angioedema were more likely to have eyelid angioedema (P = .001).

“Our findings indicate that CHA patients tend to be older, have more severe attacks, experience greater impairment in QoL and show a poorer response to high-dose antihistamines,” the authors said.

The investigators also examined associations between body mass index (BMI) and CSU characteristics. They said previous research into the topic has yielded conflicting results in regard to questions such as how BMI affects the age of disease onset, and whether obesity might be linked with more severe cases of CSU.

The data suggested that there is a weak correlation between CSU onset age and BMI (R = 0.295; P < .001), with obese patients tending to be older at CSU onset. The authors also found that omalizumab response was linked with BMI among patients with angioedema (regardless of subtype) with patients with obesity being less likely to respond to the therapy (P = .033).

Previous research has suggested that circulating tryptase levels are associated with BMI, the authors explained, which supports the idea that mast cells may mediate the association between obesity and CSU.

“The observed association between obesity and later-onset CSU suggests that obesity in older age may serve as a contributing factor in disease development,” they noted.

As for the lower response to omalizumab among patients with obesity, the investigators said it could be related to pharmacokinetic factors.

“Given that omalizumab is administered as a fixed dose regardless of body weight in CSU, patients with higher BMI may achieve lower serum drug concentrations, resulting in reduced pharmacodynamic effects,” they said.

Based on these results, the authors concluded clinicians may want to consider BMI when treating patients with CSU. Still, they said more research will be needed before the exact nature and contours of the relationship between BMI and CSU is fully understood.

References

1. Toprak İD, Celik Kamaci S, Hormet Igde M, et al. Heterogeneity in clinical appearance of chronic spontaneous urticaria: A cross-sectional analysis of a retrospective cohort. World Allergy Organ J. 2026;19(3):101353. doi:10.1016/j.waojou.2026.101353

2. Maurer M, Kolkhir P, Pereira MP, et al. Disease modification in chronic spontaneous urticaria. Allergy. 2024;79(9):2396-2413. doi:10.1111/all.16243