Assessing bronchodilator response by changes in per cent predicted forced expiratory volume in one second

Area of Science:

• Pulmonary Medicine
• Respiratory Physiology
• Diagnostic Testing

Background:

• Bronchodilator responsiveness (BDR) assessment in spirometry traditionally uses a binary classification (present/absent).
• This binary approach has limitations and pitfalls in accurately characterizing airflow improvement after bronchodilator (BD) administration.
• A novel five-category system for BDR has been developed to provide a more detailed evaluation.

Purpose of the Study:

• To redefine and validate a novel, five-category classification for bronchodilator responsiveness (BDR) in spirometry.
• To establish new BDR categories based on delta post-BD-pre-BD FEV1 % predicted values using Global Lung Initiative (GLI) equations.
• To assess the performance and generalizability of the proposed BDR partition across large spirometry cohorts.

Main Methods:

• Analysis of a large dataset (n=31,598 tests) from spirometry cohorts across two institutions.
• Redefinition of BDR categories using intervals of delta post-BD-pre-BD % predicted FEV1.
• Testing, training, and validation of the proposed BDR partition model on these cohorts, including a subset with normal baseline spirometries.

Main Results:

• The novel BDR partition model demonstrated good performance across all five categories in testing, training, and validation cohorts.
• A higher misclassification rate was observed in a validation set with normal baseline spirometries, potentially due to prior bronchodilator use.
• The proposed thresholds (≤0%, 0%-2%, 2%-4%, 4%-8%, >8% delta % predicted FEV1) showed low variance and were largely independent of gender and race.

Conclusions:

• A refined five-category BDR classification using delta % predicted FEV1 intervals is a potentially valid and user-friendly tool for spirometry.
• This novel partition offers a more granular assessment of bronchodilator response compared to traditional binary methods.
• Further validation in diverse cohorts and populations is recommended to confirm the utility of this enhanced BDR assessment.