Background Currently available studies show that removal of subjects affected by occupational asthma from exposure does not always lead to an improvement in respiratory function. The cause of this is still unclear. The aim of our study was to evaluate in 2017 lung function and severity of asthma in subjects who underwent specific inhalation challenge (SIC) between 2006 and 2015 for work-related asthma.

Methods Clinical charts of 35 workers who underwent SIC have been evaluated. They were interviewed by telephone using a questionnaire to asses demographic data, respiratory symptoms and work disability. The severity of asthma was evaluated according to the GINA guidelines and asthma control was assessed by Asthma Control Questionnaire (ACQ). 18 workers agreed also to perform also spirometry.

Results 10 subjects had a positive SIC and 25 a negative SIC. Subjects with positive SIC had more frequently moderate persistent asthma treated with a combination of inhaler steroids and a bronchodilator (67%) and those with negative SIC had more frequently intermittent asthma (65%) treated with salbutamol as needed (p<0.05). The score of ACQ was greater among subjects with positive SIC than with negative SIC (11 vs 4, p<0.05). Spirometry on 18 subjects showed among those with positive SIC a FEV1 lower (- 6% in mean) and a RV greater (+15%) compared to those with negative SIC. Subjects with positive SIC had more economic loss than subjects with negative SIC (p<0.05).

Conclusions Subjects who have had a positive SIC showed more severe asthmatic symptoms with lower asthma control despite current pharmacological therapy. They also had a higher RV than subjects with negative SIC. This could be a relevant parameter to evaluate in subjects with occupational asthma to improve asthma control.