LAUSR

Background: The effects of high-risk environment on young adults with mild asthma were never fully tested in practice, as most high-risk occupations do not welcome them. This study examines the effect of combat training on asthma worsening in the Israeli Defense Forces. Methods: Persons with asthma in remission and mild intermittent asthma who underwent combat training between 2014 and 2017 were compared in terms of disease worsening to their counterparts performing clerical duties during a follow-up of 8 months. Among combat trainees, exposure to known triggers for asthma exacerbation and health status on enlistment were assessed as risk factors for asthma exacerbation. Results: Asthma worsening among persons with asthma in remission was twice as common among those who are undergoing training compared to persons performing clerical duties. This difference was smaller among mild intermittent asthmatics. For both asthma severities, rates of asthma exacerbation requiring emergency room treatment were several times higher among the training group. Among individuals undergoing training, mild intermittent asthma was a significant risk factor for asthma worsening compared to asthma in remission (OR 1.99 [1.44–2.75]) while age (OR 0.67 [0.53–0.85]) and immigration to Israel (OR 0.55 [0.31–0.95]) were significant protective factors. Interpretation: Young adults with mild asthma are at significant risk for severe exacerbations when exposed to high-risk environment even among individuals who have long been symptom free. No single risk factor was found to have an independent effect suggesting a synergistic mechanism that is harder to mitigate.