INVESTIGATING SEVERE AND FATAL ASTHMA

Background: Severe asthma continues to present a major therapeutic pro blem despite advances in our understanding of the disease. Innovative ideas for investigating the underlying causes and treatment of severe asthma are few, and many patients still become dependent on oral stero ids. We describe two separate studies: first, a prospective investigat ion measuring the responses of persons with severe asthma to an allerg en-free environment; second, a retrospective analysis of factors assoc iated with eight fatalities and one near fatality caused by asthma exa cerbations. Methods: In the prospective study 17 persons with severe a sthma were admitted to a hospital clinical research unit containing an allergen-free room for steroid dose reduction. Peak flow measurements treatment requirements, and evidence of infection were followed up. I n the retrospective study, the cases of nine patients who had been eva luated for asthma and who subsequently died during an asthma attack we re reviewed; where possible allergen levels in their house dust and sp ecific IgE antibodies to common indoor allergens were measured. Result s: Analysis of the patients in the prospective study revealed two cate gories of responses to steroid dose reduction: (1) asthmatic persons w ho either maintained or improved peak flow values on steroid reduction ; these patients were predominantly allergic to indoor allergens; (2) asthmatic persons whose condition deteriorated; these patients were un able to tolerate reduction in steroid dose. The second group included persons with sensitization to fungal antigens who had asthmatic exacer bations in association with culture-documented fungal colonization. Th e retrospective study revealed that in five of the eight fatalities ca used by asthma, exposure to a relevant allergen had occurred at home b efore death. Conclusion: Some steroid-dependent persons with severe as thma are allergic to inhalant allergens and may benefit from avoiding allergens. In some cases there is no evidence that antigen exposure fr om diet, inhalants fungal infections, or sinusitis is relevant to thei r disease. However, persons with severe asthma include individuals inf ected with and sensitized to fungal antigens. The results suggest that cases of severe asthma should be investigated to identify treatable c auses.