Abstract
BackgroundIsocyanates are among the most common causes of occupational asthma (OA) in Switzerland. Patients with OA have been shown to have unfavourable medical, socioeconomic and psychological outcomes. We investigated long-term asthma and the socio-economic outcomes of diisocyanate-induced asthma (DIA) in Switzerland.Patients and methodsWe conducted an observational study on 49 patients with DIA and followed 35 of these patients over a mean exposure-free interval of 12 ± 0.5 (range 11.0-13.0) years. At the initial and follow-up examinations, we recorded data on respiratory symptoms and asthma medication; measured the lung function; and tested for bronchial hyperreactivity. We allowed the patients to assess their state of health and overall satisfaction using a visual analogue scale (VAS) at these visits.ResultsThe 35 patients whom we could follow had a median symptomatic exposure time of 12 months, interquartile range (IQR) 26 months and a median overall exposure time of 51 (IQR 104) months. Their subjective symptoms (p < 0.001) and the use of asthma medication (p = 0.002), particularly the use of inhaled corticosteroids (p < 0.001), decreased by nearly 50%. At the same time, the self-assessment of the patients’ state of health and overall satisfaction increased considerably according to both symptomatology and income. In contrast, slight reductions in terms of FVC% predicted from 102% to 96% (p = 0.04), of FEV1% predicted from 91% to 87% (p = 0.06) and of the FEV1/FVC ratio of 3%; (p = 0.01) were observed while NSBHR positivity did not change significantly. In univariate as well as multivariate logistic analyses we showed significant associations between age, duration of exposure and FEV1/FVC ratio with persistent asthma symptoms and NSBHR.ConclusionsWe found that the patients’ symptoms, the extent of their therapy and the decrease in their lung volumes during the follow-up period were similar to the findings in the literature. The same hold true for some prognostic factors, whereas the patients’ self-assessment of their state of health and overall satisfaction improved considerably.
Highlights
Isocyanates are among the most common causes of occupational asthma (OA) in Switzerland
Slight reductions in terms of forced vital capacity (FVC)% predicted from 102% to 96% (p = 0.04), of forced expiratory volume in 1 second (FEV1)% predicted from 91% to 87% (p = 0.06) and of the FEV1/FVC ratio of 3%; (p = 0.01) were observed while nonspecific bronchial hyperreactivity (NSBHR) positivity did not change significantly
In univariate as well as multivariate logistic analyses we showed significant associations between age, duration of exposure and FEV1/FVC ratio with persistent asthma symptoms and NSBHR
Summary
Isocyanates are among the most common causes of occupational asthma (OA) in Switzerland. We investigated long-term asthma and the socio-economic outcomes of diisocyanate-induced asthma (DIA) in Switzerland. For more than two decades diisocyanates, a group of highly reactive and widely used chemicals, were one of the most common causes of occupational asthma in industrialised countries [1] though the incidence of diisocyanate induced occupational asthma (DIA) seems to have decreased over recent years [2,3,4]. Follow-up studies published during the last 20 years have shown a poor outcome for DIA even in the absence of additional exposure to the offending agent. We decided to do a long-term study with our own DIA patients beginning in 1993 and covering a time period of at least 10 years. In 2000 and in 2003, two carefully conducted studies on the outcome of patients with DIA over a 12-year follow-up were published [19,20]
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