Tests can predict those most at-risk from thunderstorm asthma

Professor Jo Douglass

Melbourne researchers have identified the tests that can best predict who is at highest risk from thunderstorm asthma.

The findings provide some granularity given the near-universal prevalence of seasonal allergic rhinitis among patients with thunderstorm asthma and the fact that all 10 deaths in the disastrous November 2016 event in Melbourne occurred in people with known asthma.

The research, led by Professor Jo Douglass from the University of Melbourne and Royal Melbourne Hospital, comprised 228 adults with seasonal allergic rhinitis (SRA 35%), people with a past history of thunderstorm asthma symptoms (O-TA 37%), and those with thunderstorm asthma requiring presentation to hospital (H-TA 28%).

The study found blood eosinophils >0.3 x109 was significantly associated with thunderstorm asthma (OR 3.7; p <0.001)

“Similarly, a moderate or higher level of ryegrass pollen specific IgE (RGP-spIgE) was associated with a 5-fold increase in the risk of previous thunderstorm asthma.”

“A pre-bronchodilator FEV1 below the lower limit of normal (LLN) was associated with a 7·5-fold increase in the odds of H-TA (95% CI 3·1 to 18) and each 1% increase in the pre-bronchodilator FEV1 percent predicted was associated with a 5% reduction in the odds of H-TA (95% CI 0·93 to 0·97)., and scored over a certain high threshold of blood specific immunoglobulin E (lgE) to rye-grass pollen.”

Rhinitis severity, as measured by SNOT-22, was not associated with a history of thunderstorm asthma.

The study, published in the Journal of Allergy and Clinical Immunology, said RGP-spIgE was readily available from community pathology services.

“It is notable that, of those who died due to thunderstorm asthma during the November 2016 event, RGP-spIgE results were universally greater than 10·1 kU/L, adding support to the use of this threshold as a marker of increased H-TA risk.”

“Risk assessments based on our findings may be performed on easily accessible clinical tools.”

“Informed thunderstorm asthma risk amongst people with seasonal allergic rhinitis will enable targeted public health direction on appropriate risk avoidance behaviour and prescription of asthma treatments for those most at risk, including inhaled corticosteroids or combination preventive inhalers and immunotherapy that might otherwise be perceived as unwarranted.”

Most thunderstorm asthma events have occurred in November after a thunderstorm preceded by three days of high pollen counts and warm days.

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