Mild Improvement in Symptoms and Pulmonary Function in a Long-Term Follow-Up of Patients with Toluene Diisocyanate-Induced Asthma

Abstract

Background: Long-term follow-up of diisocyanate-induced occupational asthma has been occasionally reported. Methods: We studied the outcome of toluene diisocyanate (TDI)-induced asthma in 46 patients at diagnosis and after a follow-up of 11 ± 3.6 years. Symptoms, anti-asthma therapy, forced expiratory volume in 1 s (FEV₁) and bronchial hyperresponsiveness to methacholine were assessed. Results: A significant improvement in FEV₁ (% predicted) and PD20FEV₁ methacholine was observed at follow-up in comparison with diagnosis. Anti-asthma treatment was performed by 42% of patients at diagnosis and by 70% at follow-up. At the time of follow-up, 32 subjects had been removed from exposure for 6.0 ± 6.9 years, whereas 14 subjects continued to work with reduced exposure to TDI. There was a significant reduction in the prevalence of attacks of shortness of breath and dyspnoea at follow-up, but only in unexposed patients. PD20FEV₁ was significantly improved only in patients with a lower FEV₁ at diagnosis and in those who have ceased work. Logistic regression analysis, using different models with some independent variables, showed that there were no significant determinants of improvement in FEV₁ at follow-up, while a shorter duration of symptoms before diagnosis was a significant predictor of improvement in PD20FEV₁ at follow-up. Conclusions: Asthma-like symptoms, bronchial hyperresponsiveness and airway obstruction improved, but did not normalize, after a long-term follow-up with cessation or reduction in TDI exposure, mainly in subjects with an early diagnosis of occupational asthma and in patients with a lower baseline FEV₁ no longer exposed to TDI.

1,25-Dihydroxyvitamin D3 prevents toluene diisocyanate-induced airway epithelial barrier disruption

“…TDI-induced asthma is characterized by AHR, Th2-dominated airway inflammation and granulocytic infiltration (15,16) and is often associated with a poor prognosis. Airway inflammation tends to persist despite inhaled steroid medication even after the cessation of the exposure (17,18). Although there is debate concerning its etiopathogenesis, in our study, mice with TDI-induced asthma displayed similar characteristics as those of affected patients: AHR and inflammatory cell infiltration, higher levels of serum IgE, as well as an imbalanced Th1/Th2 response.…”

The effectiveness of removal from exposure and reduction of exposure for managing occupational asthma: Summary of an updated Cochrane systematic review

“…Several studies of workplace interventions for OA were published after the 2011 review. With a comprehensive approach of including recently published studies, [9][10][11][12] along with those studies already identified in the 2011 Cochrane review, we produced an updated systematic review of evidence on the effectiveness of workplace interventions for the treatment of OA. 13…”