Background: We examined the relationship between pulmonary function (FEV 1 ) 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 fi rst year after September 11, 2001. Confirmed recovery was defined as reporting no LRSs on two consecutive and all subsequent examinations. FEV 1 was assessed at the fi rst post-September 11, 2001, examination and at each examination where symptom information was ascertained. We used stratified Cox regression models to analyze FEV 1 , WTC exposure, and other variables in relation to confirmed symptom recovery.
Results: A total of 4,368 fi refighters met inclusion criteria and were symptomatic at year 1, of whom1,592 (36.4%) experienced confirmed recovery. In univariable models, fi rst post-September 11,2001, concurrent, and difference between fi rst post-September 11, 2001, and concurrent FEV 1 values were all significantly associated with confirmed recovery. In adjusted analyses, both fi rst post-September 11, 2001, FEV 1 (hazard ratio [HR], 1.07 per 355-mL difference; 95% CI, 1.04-1.10) and FEV 1 % 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 FEV 1 , 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 FEV 1 and improvement in FEV 1 after September 11, 2001, predicted confirmed LRS recovery, supporting a physiologic basis for recovery and highlighting consideration of spirometry as part of any postexposure respiratory health assessment.