Standardization of spirometry in assessment of responders following man-made disasters: World Trade Center worker and volunteer medical screening program

Background: Spirometry is the most commonly used pulmonary function test to screen individuals for suspected lung disease. It is also used for screening workers with exposures to agents associated with pulmonary diseases. Although the American Thoracic Society (ATS) provides guidelines for spirometers and spirometry techniques, many factors are not standardized, so that results from individual pulmonary function laboratories vary substantially. These differences can create substantial difficulties in using data pooled from multiple sites to understand health consequences of disasters that involve exposures to pulmonary toxins. This article describes the approach used to minimize these differences for a consortium of institutions who are providing medical monitoring examinations to World Trade Center (WTC) responders. The protocol improved upon the minimal ATS guidelines.

Methods: Spirometric measurements were obtained before and after use of a bronchodilator. A fourth-generation spirometer was chosen that exceeded ATS spirometer accuracy standards. The accuracy was verified at the beginning of each day of testing. Technologists who performed the spirometry tests were centrally trained and certified and received regular reports on their performance. Reference values and normal ranges were obtained from the National Health and Nutrition Examination Survey (NHANES III) data set. A standardized interpretation flowchart was followed to reduce misclassification rates for airway obstruction and restriction. Patients with spirometric abnormalities were referred for more extensive diagnostic testing.

Results: More than 12,000 spirometry tests were performed during the first examination. The 20 spirometers used at the 6 participating institutions maintained accuracy within 3% for more than 4 years. Overall, more than 80% of the test sessions met ATS quality goals. Spirometry abnormality rates exceeded those obtained for adults who participated in the NHANES III survey.

Conclusions: The program allowed standardization of the performance and interpretation of spirometry results across multiple institutions. This facilitated reliable and rapid diagnosis of lung disease in the large number of WTC responders screened. We recommend this approach for postdisaster pulmonary evaluations in other settings.