Zureik M, Neukirch C, Leynaert B, et al. BMJ. 2003;325:411–417
Purpose of the Study.
To assess whether the severity of asthma is associated with sensitization to airborne molds rather than to other seasonal or perennial allergens.
One thousand one hundred thirty-two adults 20 to 44 years old with current asthma and with skin prick test results.
Participating centers of the European Community Respiratory Health Survey of over 30 centers (13 countries) randomly selected samples of 20- to 44-year-olds. They completed a short postal questionnaire about asthma symptoms. Twenty percent of random subsamples from this group were invited to come to a test center for skin prick and blood tests, spirometry, and methacholine challenge. Severity of asthma was determined according to score based on forced expiratory volume in 1 second, number of asthma attacks, hospital admission for breathing problems, and use of corticosteroids in the past 12 months.
The frequency of sensitization to molds (Alternaria alternata or Cladosporium berbarum, or both) increased significantly with increasing asthma severity (odds ratio: 2.34; 95% confidence interval: 1.56–3.52) for either severe or mild asthma). This association existed in all of the study areas (gathered into regions), although there were differences in the frequency of sensitization. There was no association between asthma severity and sensitization to pollens or cats. Sensitization to Dermatophagoides pteronyssinus was also positively associated with severity. In multivariable logistic regressions including sensitization to molds, pollens, D pteronyssinus, and cats simultaneously, the odds ratios for sensitization to molds were 1.48 (0.97 or 2.25) for moderate mild asthma and 2.16 (1.37–3.35 for severe mild asthma (P < .001).
Sensitization to molds is a powerful risk factor for severe asthma in adults. This should be taken into account in primary prevention, management, and patients’ education.
This is an interesting study of adults living in multiple countries and environments showing that sensitization to Alternaria and Cladosporium were actually associated with more severe asthma while sensitization to pollens and pets were not. Dust mite sensitization was also associated with more severe asthma as has been observed in previous studies. Previous studies have shown that exposure and sensitization to molds is associated with death from asthma and life-threatening exacerbations. However, this is the first population-based study that used criteria other than just health care attendance alone, and included spirometry, steroid use, and frequency of asthma attacks. It is also interesting to see that mold was important in various areas of the world and different environments.