An epidemic of thunderstorm asthma in Melbourne 2016: asthma, rhinitis, and other previous allergies

Abstract

Background: On 21st November 2016, Melbourne experienced an epidemic of 'thunderstorm asthma.' Although previously described in the literature, risk factors and natural history remain incompletely understood.

Objective: Our aim was to follow up those presenting to the 3 Emergency Departments (EDs) in our health service during the epidemic, and assess their history for previous asthma, rhinitis, and allergies.

Methods: ED notes of all respiratory presentations within 48 hours of the thunderstorm event were reviewed and patients with acute asthma included. A standardised questionnaire was devised encompassing asthma diagnosis, undiagnosed asthma symptoms and rhinitis severity. Patients were contacted by phone within 30 days of the event.

Results: Three hundred forty-four patients were identified overall; 263 patients were contactable and completed a phone or mail questionnaire. The mean age was 32.7 ± 19.2 years (range, 6 months-87 years; 25% < 18 years) with 58% male sex. A previous diagnosis of asthma was present in 42% (n = 111), and there was no previous asthma diagnosis in 58% (n = 152). Of those who had no asthma diagnosis 53% had probable undiagnosed asthma. Overall, rhinitis prevalence was 88%, of which 72% were moderate or severe (Allergic Rhinitis and its Impact on Asthma guidelines) and 51% (n = 133) reported a history of grass pollen allergy.

Conclusion: Our data highlights the importance of atopy and rhinitis as risk factors for epidemic thunderstorm asthma. Better identification of undiagnosed asthma, and implementing treatment of asthma and rhinitis may be important.

Keywords: Asthma; Rhinitis, allergic, seasonal; Thunderstorm.

Fig. 1. Consort diagram of epidemic thunderstorm asthma patients. ED, Emergency Department.

Fig. 2. Prevalence of asthma and probable undiagnosed asthma. Current asthma: previous diagnosis of asthma with symptoms in the last 12 months; Past asthma: previous diagnosis of asthma with no symptoms in the last 12 months; Probable undiagnosed asthma: no diagnosis of asthma, but symptoms to suggest asthma; No asthma: no diagnosis of asthma and no symptoms to suggest asthma.