Asthma control in severe asthma and occupational exposures to inhalable asthmagens.

Introduction: Work-related asthma accounts for ≥25% of asthma in working-age populations, though the relationship between work exposures and symptoms is frequently missed, leading to poor health and employment outcomes. We hypothesised that inhalable exposures at work are associated with poor asthma control in severe asthma (SA).

Methods: We searched the Birmingham (UK) Regional NHS SA Service clinical database (n=1453 records; 1 March 2004 to 1 March 2021) and undertook a cross-sectional study using baseline data collected at diagnosis. We included all employed patients aged 16-64 with documented current occupation (n=504), and collected socio-demographic, general health and asthma-specific data, including Asthma Control Questionnaire 7 (ACQ7) score. The Occupational Asthma Specific Job-Exposure Matrix (OAsJEM) was employed to determine the likelihood of exposure to respiratory sensitisers, irritants, cleaning agents and detergents; associations between exposures and ACQ7 were investigated using binary and multinomial regression.

Results: Frequently reported occupations were care assistants (7%) and nurses (6%); 197/504 (39%) patients were exposed to an asthmagen, including respiratory sensitisers (30%), airway irritants (38%) and cleaning products/disinfectants (29%). ACQ7 score was available for 372/504 (74%) patients, of whom 14% had adequate control (ACQ7=0-1.5). After adjustment for major confounders there were no significant associations between inhaled asthmagens and ACQ7 score (either as binary or multinomial outcomes).

Conclusion: JEM-determined workplace exposures to inhaled asthmagens are not associated with asthma control in SA; 29-39% of patients may have current exposure to workplace asthmagens. Routine collection of lifetime occupational data including current job role and level of exposure, in the national asthma registry, would give further insights into this relationship.