Elevated levels of blood ryegrass pollen–specific IgE (RGP-sp IgE) antibodies, eosinophils and fractional exhaled nitric oxide (FeNO) are risk factors for thunderstorm asthma in individuals with seasonal allergic rhinitis, says a study from Australia reported in the Journal of Allergy and Clinical Immunology.¹

In the multicenter Thunderstorm Asthma in Seasonal Allergic Rhinitis (TAISAR) study, Douglass et al set out to examine the risk factors for a history of thunderstorm asthma in persons with seasonal allergic rhinitis. They included 228 individuals with a past diagnosis of thunderstorm asthma and/or self-reported seasonal allergic rhinitis. Clinical features and biomarkers such as spirometry (FEV1), WBC count, ryegrass pollen-specific (RGP-sp) IgE level and fractional exhaled nitric oxide were used to identify risk factors.

Thirty-five percent of the participants reported only seasonal allergic rhinitis without a history of thunderstorm asthma (isolated seasonal allergic rhinitis; I-SAR group) and 37% had a history of thunderstorm asthma but did not need hospitalization for treatment (outpatient thunderstorm asthma; O-TA group). Twenty-eight percent were hospitalized for treatment (hospitalized with thunderstorm asthma; H-TA group) and all of them had co-existent asthma. RGP-sp IgE level >10.1 kU/L and a prebronchodilator FEV1 value ≤ 90% were indicators of risk for hospitalization for thunderstorm asthma. Asthma Control Questionnaire score >1.5, high eosinophil counts and fractional exhaled nitric oxide were also associated with both O-TA and H-TA.

Simply put, acute bronchospasm that occurs right after a thunderstorm, particularly during pollen season is referred to as thunderstorm asthma; the most common pollen being grass pollen. During a thunderstorm, the pollen particles “aeroallergens” get fragmented into minuscule particles, which are easily inhalable and act as triggers for asthma in sensitized individuals. Most people who experience thunderstorm asthma have seasonal allergic rhinitis or allergy to the grass pollen. Less than half have a history of asthma. Persons who stay at home during thunderstorms and keep doors and windows closed are generally not affected.²

This study has identified risk factors, namely high pollen-specific IgE levels, eosinophil counts and FeNO for thunderstorm asthma. Poorly-controlled asthma also enhances the risk. It can occur even in persons who do not have a history of asthma. Assessment for these factors can identify at-risk individuals and facilitates timely adoption of preventive measures. Thunderstorm asthma, therefore, is a condition that clinicians should be aware of and they should also educate their patients with seasonal allergic rhinitis and/or asthma about avoiding thunderstorms occurring during pollen seasons to reduce risk of asthma exacerbations.

References

1. Jo A Douglass, et al. Thunderstorm asthma in seasonal allergic rhinitis: The TAISAR study. J Allergy Clin Immunol. 2022 May;149(5):1607-1616. doi: 10.1016/j.jaci.2021.10.028.
2. Ajay Kevat.  Thunderstorm asthma: looking back and looking forward. J Asthma Allergy. 2020 Sep 8;13:293-299.