Longitudinal assessment of spirometry in the world trade center medical monitoring program

Background: Multiple studies have demonstrated an initial high prevalence of spirometric abnormalities following World Trade Center (WTC) disaster exposure. We assessed prevalence of spirometric abnormalities and changes in spirometry between baseline and first follow-up evaluation in participants in the WTC Worker and Volunteer Medical Monitoring Program. We also determined the predictors of spirometric change between the two examinations. Methods: Prebronchodilator and postbronchodilator spirometry, demographics, occupational history, smoking status, and respiratory symptoms and exposure onset were obtained at both examinations (about 3 years apart). Results: At the second examination, 24.1% of individuals had abnormal spirometry findings. The predominant defect was a low FVC without obstruction (16.1%). Between examinations, the majority of individuals did not have a greater-than-expected decline in lung function. The mean declines in prebronchodilator FEV₁ and FVC were 13 mL/yr and 2 mL/yr, respectively (postbronchodilator results were similar and not reported). Significant predictors of greater average decline between examinations were bronchodilator responsiveness at examination 1 and weight gain. Conclusions: Elevated rates of spirometric abnormalities were present at both examinations, with reduced FVC most common. Although the majority had a normal decline in lung function, initial bronchodilator response and weight gain were significantly associated with greater-than-normal lung function declines. Due to the presence of spirometric abnormalities > 5 years after the disaster in many exposed individuals, longer-term monitoring of WTC responders is essential.