Abstract Rationale The 2019 ATS-ERS Spirometry technical standard defines an acceptable End of Forced Exhalation (EOFE) by one of the following criteria: volume change over the last second ≤ 0.025 L; or forced expiratory time (FET) 15 seconds; or repeatability of FVC, the latter citing pediatric patients and those with restrictive lung disease who might struggle meeting the volume change over the last second criteria secondary to high elastic recoil. However, there is no discussion on patients with obstructive diseases that surpass a time limit, appear to be empty, yet fail to meet the other two criteria. We evaluated a model using a greater EOFE flowrate and varying expiratory times to reduce the number of clinically relevant false positives identified by a computer algorithm during testing and define more practical “useable” EOFE criteria. We hypothesize that using such a model to assess EOFE in subjects with obstructive lung disease would improve the usability of data in clinical trials. Methods We reviewed 1469 subject’s anonymized data from four asthma and COPD clinical trials. 111 maneuvers from 62 subjects were marked as failed to meet the EOFE criteria by strict adherence to the ATS-ERS criteria using a computer algorithm and later changed to “acceptable” based on visual review of the flow-volume (FV) and volume-time (VT) curves by human overreading experts. We evaluated the application of varied Forced Expiratory Times (FET) against a single EOFE flow criterion to assess the impact on performance identifying clinically relevant EOFE determinations. Results Using the flow criterion of 0.100 L volume change over the last second and various expiratory times we were able to demonstrate an increase in maneuvers deemed “useable”, which more closely aligned with the overreaders’. Figure 1 shows the scatter plot of data below 0.100L with varying time cut points (left) and the percentage of tests (right) that would better align with the overreaders’ assessment. Figure 1 Conclusion In this limited feasibility study, it appears that applying a 6 second minimum expiratory time (2005 ATS-ERS Spirometry Standard) and 0.100L in the last second EOFE flowrate yields increased computer algorithm generated “usable” FVC data by 72.1%, aligning human overreaders’ visual inspection of spirometry curves. Application of this model in a larger cohort should be pursued to support the conclusion. This abstract is funded by: None
Mottram et al. (Fri,) studied this question.
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