[Is the severity of occupational asthma related to the molecular weight of the allergen?].

INTRODUCTION

The aim of the study was to compare the characteristics of occupational asthma (OA) resulting from sensitisation to allergens of high (HMW) or low (LMW) molecular weight.

METHODS

All new cases of allergic OA seen in an occupational health department between January 2001 and March 2004 were included. The patients underwent a standardised assessment including a questionnaire, skin tests, spirometry and measurement of non-specific bronchial reactivity. They were divided into 2 groups depending on the molecular weight of the causal agent (groups HMW and LMW).

RESULTS

77 patients were included, 30 in the HMW group and 47 in the LMW group. No significant difference in severity at the time of diagnosis was found between the two groups (symptoms, spirometry, PD20 methacholine) but the time between the first symptoms and diagnosis was longer in the HMW group (7.1 +/- 7.8 years against 3.2 +/- 4.1 years, p = 0.01). Atopy was more common in the HMW group (57% vs. 27%, p = 0.01).

CONCLUSION

The severity of OA at the time of diagnosis does not appear to be influenced by the molecular weight of the causal agent.