The Advantages of FEV₁ Percent Predicted Change During Bronchial Challenge Testing.

Area of Science:

• Pulmonary Medicine
• Respiratory Physiology
• Clinical Diagnostics

Background:

• Methacholine challenge testing traditionally uses a 20% fall in forced expiratory volume in one second (FEV1) from baseline.
• A higher baseline FEV1 necessitates a greater absolute volume change to reach the 20% fall threshold.
• This can introduce variability and dependence on pre-test lung function measurements.

Purpose of the Study:

• To evaluate the utility of using a percentage predicted fall in FEV1 for bronchial challenge testing.
• To determine if a 15% predicted fall (PD15%) is a more reliable and efficient alternative to the standard 20% absolute fall (PD20).

Main Methods:

• Re-analysis of methacholine challenge data from 114 asthma patients.
• Comparison of the standard PD20 criteria with a novel PD15% criteria for classifying bronchial hyperresponsiveness.

Main Results:

• Strong agreement was found between PD20 and PD15% (r=0.95, ICC=0.97).
• PD20 values were significantly higher than PD15% values, with greater FEV1 decreases observed for PD20 (21.4% vs 19.1%).
• The PD15% method showed less dependence on baseline FEV1 and was less affected by FEV1 variability between visits compared to PD20.

Conclusions:

• A PD criteria based on a 15% predicted change in FEV1 is recommended for bronchial challenge testing.
• This method offers improved efficiency and safety by reducing influence from baseline airflow obstruction.
• The PD15% approach provides a more standardized measure of airway hyperresponsiveness.