Pulmonary function predicting confirmed recovery from lower-respiratory symptoms in world trade center-exposed firefighters, 2001 to 2010

Background: We examined the relationship between pulmonary function (FEV₁) and confirmed recovery from three lower-respiratory symptoms (LRSs) (cough, dyspnea, and wheeze) up to 9 years after symptom onset. Methods: The study included white and black male World Trade Center (WTC)-exposed firefighters who reported at least one LRS on a medical monitoring examination during the first year after September 11, 2001. Confirmed recovery was defined as reporting no LRSs on two consecutive and all subsequent examinations. FEV₁ was assessed at the first post-September 11, 2001, examination and at each examination where symptom information was ascertained. We used stratified Cox regression models to analyze FEV₁, WTC exposure, and other variables in relation to confi rmed symptom recovery. Results: A total of 4,368 firefighters met inclusion criteria and were symptomatic at year 1, of whom 1,592 (36.4%) experienced confirmed recovery. In univariable models, first post-September 11, 2001, concurrent, and difference between first post-September 11, 2001, and concurrent FEV₁ values were all significantly associated with confirmed recovery. In adjusted analyses, both first post- September 11, 2001, FEV₁ (hazard ratio [HR], 1.07 per 355-mL difference; 95% CI, 1.04-1.10) and FEV₁ % predicted (HR, 1.08 per 10% predicted difference; 95% CI, 1.04-1.12) predicted confirmed recovery. WTC exposure had an inverse association with confirmed recovery in the model with FEV₁, with the earliest arrival group less likely to recover than the latest arrival group (HR, 0.73; 95% CI, 0.58-0.92). Conclusions: Higher FEV₁ and improvement in FEV₁ after September 11, 2001, predicted confi rmed LRS recovery, supporting a physiologic basis for recovery and highlighting consideration of spirometry as part of any postexposure respiratory health assessment.