The identification of the factors associated with severe asthma may shed some light on its etiology and mechanisms.
A cross-sectional, population-based sample in Europe (1999-2002) included 1,241 adults with asthma.
About 30% of asthmatic subjects were affected by moderate-to-severe asthma.
Sensitization to Cladosporium was associated with a more than 5-fold greater risk of having persistent asthma.
Cladosporium. Image source: Wikipedia, GNU Free Documentation License.
Persistent asthma was associated with sensitization to:
- house dust mite
- nonseasonal asthma
- an older age at asthma onset
- chronic cough and phlegm
Sensitization to cat increased the risk of severe asthma.
Smoking was associated with asthma severity in men, while rhinitis was associated with asthma severity in women.
The authors concluded that one third of the asthmatic population have moderate-to-severe asthma. Sensitization to perennial indoor allergens, particularly Cladosporium, is associated with asthma severity.
Cladosporium is a genus of fungi including some of the most common indoor and outdoor molds. It produces olive-green to brown or black colonies, and its dark-pigmented conidia are formed in simple or branching chains.
Cladosporium species may grow indoors on surfaces when moisture is present. Cladosporium produces volatile organic compounds (VOCs) associated with odors.
Asthma Severity According to Global Initiative for Asthma and Its Determinants: An International Study. Cazzoletti L, Marcon A, Corsico A, Janson C, Jarvis D, Pin I, Accordini S, Bugiani M, Cerveri I, Gislason D, Gulsvik A, de Marco R. Int Arch Allergy Immunol. 2009 Aug 7;151(1):70-79.