Background: The origin of the hesitating start criterion was not established from a peer reviewed scientific study, but was based upon clinical opinion from expert users. The primary purpose of the current study is to investigate alternative hesitating start criteria for shorter forced expiratory times with a high degree of correlation to the currently accepted method.
Methods: A total of 1,719 workers met eligibility criteria for this study and contributed 24,945 trials. The primary purpose was to find the slope of the regression of EV/FVC on EV/FEV1, EV/FEV3, and EV/FEV6.
Results: From regression analyses, the values for EV/FEV1, EV/FEV3, and EV/FEV6 corresponding to the five percent EV/FVC value were determined to be 6.62%, 5.59%, and 5.25%, respectively. Application of the newly developed EV/FEV6 hesitating start criteria to trials truncated at six seconds resulted in 125 (0.96%) fewer trials being rejected when compared to the conventional hesitating start criteria of EV/FVC of 5%.
Conclusions: A newly derived hesitating start criterion using EV/FEV6 of 5.25% was determined. This new criterion is recommended for tracings that do not achieve a plateau, such as when a six second expiration (FEV6) is performed. Application of this new hesitating start criterion was shown to reduce the number of maneuvers falsely rejected when a plateau is not achieved.