Lung function decline before and after treatment of World Trade Center associated obstructive airways disease with inhaled corticosteroids and long‐acting beta agonists

Abstract

Background Greater than average loss of one‐second forced expiratory volume (FEV1) is a risk factor for asthma, chronic obstructive pulmonary disease (COPD), and asthma/COPD overlap syndrome in World Trade Center (WTC)‐exposed firefighters. Inhaled corticosteroids and long‐acting beta agonists (ICS/LABA) are used to treat obstructive airways disease but their impact on FEV1‐trajectory in this population is unknown. Methods The study population included WTC‐exposed male firefighters who were treated with ICS/LABA for 2 years or longer (with initiation before 2015), had at least two FEV1 measurements before ICS/LABA initiation and two FEV1 measurements posttreatment between September 11, 2001 and September 10, 2019. Linear mixed‐effects models were used to estimate FEV1‐slope pre‐ and post‐treatment. Results During follow‐up, 1023 WTC‐exposed firefighters were treated with ICS/LABA for 2 years or longer. When comparing intervals 6 years before and 6 years after treatment, participants had an 18.7 ml/year (95% confidence interval [CI]: 11.3–26.1) improvement in FEV1‐slope after adjustment for baseline FEV1, race, height, WTC exposure, weight change, blood eosinophil concentration, and smoking status. After stratification by median date of ICS/LABA initiation (January 14, 2010), earlier ICS/LABA‐initiators had a 32.5 ml/year (95% CI: 19.5–45.5) improvement in slope but later ICS/LABA‐initiators had a nonsignificant FEV1‐slope improvement (7.9 ml/year, 95% CI: −0.5 to 17.2). Conclusions WTC‐exposed firefighters treated with ICS/LABA had improved FEV1 slope after initiation, particularly among those who started earlier. Treatment was, however, not associated with FEV1‐slope improvement if started after the median initiation date (1/14/2010), likely because onset of disease began before treatment initiation. Research on alternative treatments is needed for patients with greater than average FEV1‐decline who have not responded to ICS/LABA.