A CROSS-SECTIONAL COMPARISON BETWEEN TWO TYPES OF FORCED EXPIRATORY MANEUVERS DURING PULMONARY FUNCTION SURVEILLANCE OF US COAL WORKERS, 2016-2019

Abstract

SESSION TITLE: Education, Research, and Quality Improvement Posters SESSION TYPE: Original Investigation Posters PRESENTED ON: October 18-21, 2020 PURPOSE: Recent spirometry standardization guidelines focus on the flow-volume loop maneuver [FVL] to measure both inspiratory and expiratory airflow during spirometry testing. However, many occupational health surveillance programs routinely perform ‘exhalation only’ maneuvers [EO]. Our aim was to determine spirometry quality differences based on the type of forced vital capacity (FVC) maneuver performed. METHODS: Between 2016–2019, the National Institute for Occupational Safety and Health (NIOSH) conducted health surveillance inclusive of spirometry testing for U.S. coal miners. Tests were conducted in a NIOSH mobile examination unit, by the same technicians using the same flow-type spirometer model. From 2016 to 2018, the EO-FVC maneuver was performed by miners. In 2018, NIOSH spirometry protocols were updated, and subsequent miners were tested using the FVL-FVC maneuver. We compared spirometry test quality differences between EO-FVC and FVL-FVC testing techniques. Quality metric variables of interest were number of acceptable maneuvers, repeatability of maneuvers, maximal expiration to zero flow, excessive hesitation, and overall test quality. Fisher’s exact tests identified univariate quality variable differences. Poisson regression models using SAS Proc GENMOD determined associations between the type of FVC maneuver and test-quality metrics with adjustment for sex, race, BMI, age, and test technician. RESULTS: We compared 2,010 EO-FVC and 3,340 FVL-FVC spirometry tests. Univariate analyses revealed that tests from FVL-FVC maneuvers were more likely to contain three acceptable maneuvers, be repeatable, and have quality grades ‘C ‘or better (p<0.0001, p=0.035, and p<0.0001, respectively). Exhalation to zero flow was more often achieved in EO-FVC maneuvers (p<0.0001). Poisson models indicated that FVL-FVC maneuvers produced significantly more tests with three acceptable maneuvers (PRR=1.07, 95% CI: 1.01, 1.15), and repeatable maneuvers (PRR=1.06, 95% CI: 1.01, 1.13). No significant associations were seen for excessive hesitation and maximal expiration to zero flow parameters. CONCLUSIONS: The type of FVC maneuver performed can influence spirometry test quality. FVL-FVC maneuvers were more likely to produce spirometry tests meeting criteria for acceptability and repeatability when compared to EO-FVC type maneuvers. CLINICAL IMPLICATIONS: Our findings will help inform occupational health surveillance programs as to which type of FVC maneuver they may choose to implement during worker spirometry testing. A change from the EO-FVC to FVL-FVC maneuver would also make occupational health surveillance spirometry records more comparable to spirometry testing being performed in acute care pulmonary function laboratories. DISCLOSURES: No relevant relationships by Kathleen Clark, source=Web Response No relevant relationships by scott hendricks, source=Web Response