D1.208 - Monocentric retrospective study of asthma prevalence among patients allergic to birch and grass pollens at Strasbourg University Hospital

Allergy to grass and birch pollens most commonly presents as rhinoconjunctivitis. However, the associated presence of asthma appears to be underestimated. The aim of this study was to assess the prevalence of asthma in patients allergic to these pollens and to describe its epidemiological, clinical, and paraclinical characteristics.

This was a monocentric, observational, retrospective study conducted between June and November 2024 in an allergy unit. Included patients had sensitization to birch and/or grass pollens confirmed by skin prick tests, with concordant respiratory symptoms during the relevant pollen season. Collected data included demographic characteristics, allergic comorbidities, allergy test results, lung function, blood eosinophil counts, severity scores (GINA, ACT), and treatments, including allergen immunotherapy.

A total of 201 patients were included, with a median age of 29 years [14–43], and 56% were female. Asthma was present in 76.8% of patients, including 37.3% with severe disease (≥ GINA 4), and was controlled in 68.4% of cases at the time of consultation. Regarding other allergic comorbidities, 48% had atopic dermatitis and 68.5% had food allergies. Sensitization patterns showed that 22.2% were monosensitized to grass pollens, 7.5% to birch pollens, and 67.3% had dual sensitization. Sensitization to other allergens was frequent, particularly to other tree pollens, house dust mites, and animal allergens, with mold sensitization being significantly higher in patients with severe asthma (56.7%). Mean FEV₁ was 92%. Blood eosinophilia >150/mm³ was observed in 59% of patients. Overall, 62.3% received maintenance inhaled therapy, 9% were treated with biologics, and 58.9% were receiving pollen allergen immunotherapy.

Among patients allergic to birch and grass pollens followed in a hospital setting, often with multiple sensitizations, asthma is frequent, with a high proportion of severe forms. Identifying this marker of respiratory allergy severity is therefore essential in order to optimize therapeutic management.