P8 Simplifying spirometry: is one effort enough to rule out obstructive impairment?

Technically acceptable and repeatable spirometric measures are crucial for accurate pulmonary function test (PFT) interpretation. Artificial intelligence (AI) enables automated quality assessment, indicating reliable measurements in real-time. This study investigated whether the first AI-acceptable spirometry trial can rule out obstructive impairment.Spirometry data (ndd Easy-on PC) from the Canadian Longitudinal Study of Aging (CLSA), a national prospective cohort of adults aged 45–85, were analysed using ArtiQ. QC software. All trials were assessed using 2019 American Thoracic Society/European Respiratory Society standards.The first acceptable trial (where both forced expiratory volume in one second – FEV1, and Forced Vital Capacity – FVC, were acceptable) and the best acceptable trial (FEV1 and FVC acceptable with the highest values) after at least two acceptable and repeatable trials were compared for the FEV1, FVC, and FEV1/FVC ratio using Bland-Altman plots. Race-neutral Global Lung Function Initiative (GLI) lower limits of normal (LLN) were used to classify impairment (i.e., 5th centile).Of 21,795 participants, 6,722 were excluded due to unacceptable data, leaving 15,073 for analysis. Small differences were observed between the first and best trials (mean difference in FEV1: 0.049 L [95% CI: 0.049, 0.051]; FVC: 0.053 L [95% CI: 0.052, 0.054]; FEV1/FVC: 0.0024 [95% CI: 0.002, 0.003]). Strong agreement was found between the first and best trials in ruling out obstructive impairments (99.7% sensitivity). However, the first trial falsely classified 16.6% as obstructed, highlighting potential challenges in diagnostic accuracy when relying solely on the first trial. A simplified protocol to rule out obstructive impairment could reduce testing time from 15 to 5 minutes, reducing testing time by 30% and saving an estimated 40 hours monthly.The first acceptable spirometry trial offers potential as a screening tool to rule out obstructive impairment, whereas full spirometry assessment is necessary to confirm obstructive impairment. To minimize error, a higher LLN (e.g. 10th centile) could be used to prevent false negatives.