Occupational asthma due to isocyanates:: study of 21 patients

BACKGROUND: A descriptive-evolutive study of a series of patients diagnosed with bronchial occupational asthma due to isocyanate exposure. SUBJECTS AND METHODS: Retrospective study of 21 patients diagnosed with bronchial occupational asthma due to isocyanates. Family story, clinical data, functional respiratory study, allergic and laboratory tests were collected. Clinical and functional performance one year after diagnosis was evaluated in patients who had and who had not stopped causal exposure. RESULTS: 17 men and 4 women aged 22 to 59 years were evaluated. In 5 cases (23.8%) family story of atopia was documented and 12 (57.14%) patients were smokers. Seven out of 21 patients were expossed to paint related products at work being this the most common reason. Average time (SD) from the beginning of exposure to development of symptoms was 16.10 (22.5) months. IgE levels were high in 6 (28.57%) and specific IgE to isocyanates was high in 8 (38%), in all cases bronchial hyperreactivity was detected. In 18 patients (85.7%), the study of maxim expiratory flow (MEF) register demonstrated occupational asthma while in the remaining 3 patients a provocation test was performed with positive result. In the annual follow up visit, the 17 patients who avoided casual exposure showed clinical improvement, 7 of them also whith functional improvement while in the remaining 10 patients no significant functional change was observed. On the other hand, 3 of the 4 patients who, although protected, underwent exposure, became clinical and functionally worse (p = 0.003, Fisher test). CONCLUSIONS: The etiology of occupational asthma due to isocyanates is not often assesed and usually lately diagnosed. This aspect is worth considering as the illness prognosis seems related to casual agent avoidance.