RESUMEN
Eighty-seven cases of occupational asthma induced by toluene diisocyanate (TDI) were diagnosed by an inhalation challenge with TDI and methacholine. After an average follow-up interval of 11 yrs, all subjects were re-examined. Of the 87 subjects examined, 13 (15%) had remained in the same job, 44 (50.5%) had been removed from exposure for <10 yrs and 30 (34.5%) had been removed for >10 yrs. The proportion of subjects who experienced symptoms of asthma and those who were hyperresponsive to methacholine was significantly lower. Of the patients, 59% used short-acting bronchodilators, 8% long-acting bronchodilators and 18% were on regular inhaled glucocorticoids. Thus, multiple regression analysis showed a positive correlation between forced vital capacity (FVC) and forced expiratory volume in one second (FEV1) at follow-up and FVC and FEV1 at diagnosis, and a negative correlation with smoking and with therapy with bronchodilators. Stepwise logistic regression showed that the follow-up provocative dose causing a 20% fall in the FEV1 (PD20) could be predicted from baseline PD20. These results indicate that respiratory symptoms and airway hyperresponsiveness to methacholine persist in subjects removed from exposure to TDI for >10 yrs. A more favourable prognosis was associated with a better lung function and a lower degree of airway hyperresponsiveness to methacholine at diagnosis.
Asunto(s)
Asma/inducido químicamente , Enfermedades Profesionales/inducido químicamente , 2,4-Diisocianato de Tolueno/efectos adversos , Adulto , Asma/fisiopatología , Pruebas de Provocación Bronquial , Femenino , Estudios de Seguimiento , Humanos , Modelos Logísticos , Estudios Longitudinales , Masculino , Cloruro de Metacolina , Compuestos de Metacolina , Persona de Mediana Edad , Enfermedades Profesionales/fisiopatología , Exposición Profesional , Pronóstico , Pruebas de Función RespiratoriaRESUMEN
We studied 29 subjects with latex-induced occupational asthma in a follow-up of 5 +/- 3 years. Initial and follow-up visits included a questionnaire and measurement of lung volumes, bronchial responsiveness to methacholine (PD20FEV1), and latex-specific serum IgE levels. At follow-up, 17 subjects were no longer exposed to latex, whereas 12 subjects had reduced exposure. Asthma and rhinitis symptoms, use of steroids and bronchial hyperresponsiveness improved significantly at follow-up, whereas mean FEV1% and FVC% decreased (p < 0.05). Multiple regression analysis showed that the main determinant of FEV1 and PD20FEV1 at follow up were the values of these variables at diagnosis. Complete recovery of occupational asthma was observed in 7 subjects (24%), all in the non-exposed group. Latex-specific IgE did not exhibit significant changes. In conclusion latex-induced occupational asthma improves after a follow-up of 5 +/- 3 years, but a complete recovery occurs in a minority of subjects and is associated with cessation of exposure. Lung function measurements at follow up depend from their impairment at the time of diagnosis.