The prevalence of allergy to pollen is increasing. Alyatec is a clinical trial center running an environmental exposure chamber and collects medical information on allergic patients.

The purpose of this study was to assess the frequency of allergic respiratory diseases and their comorbidities, and to identify pollen-related asthma in allergic patients, using the Alyatec database.

Alyatec database counts 2079 allergic patients included with skin prick testing for common aeroallergens, medical and allergy history. Patients gave their consent to be included in this General Data Protection Regulation (GDPR)-compliant database.

The mean age was 35.3 years, with 60 % women. The majority lived in the Strasbourg area. Asthma was found in 71 %, 99 % had rhinitis, 90 % had conjunctivitis, and 71 % had both, asthma and rhinitis. They were polysensitized: 64 % to house dust mites, 66 % to cats, 57 % to birch pollen, and 69 % to grass pollen; 77 % had mild asthma with 71 % controlled asthma. Among patients sensitized to pollen, 46 % of those with a birch pollen allergy and 43 % of those with a grass pollen allergy were asthmatic. Similar results were obtained in patients with allergic rhinitis without asthma caused by birch and grass pollen during airborne allergen exposures in Alyatec environmental exposure chamber: early asthma responses were observed in 53 % of birch pollen-allergic patients and 50 % of grass pollen-allergic patients.

Asthma to birch and grass pollen appears to be more common than previously described and should be better considered in future allergen immunotherapy trials.