Differences in severity grading of lung hyperinflation using GLI versus ECSC reference values.

Area of Science:

• Pulmonary Function Testing
• Respiratory Medicine
• Clinical Diagnostics

Background:

• The Global Lung Initiative (GLI) network updated lung function reference equations in 2021.
• These new equations established revised normal ranges for lung hyperinflation indices.
• This impacts the classification and severity grading of lung hyperinflation.

Purpose of the Study:

• To evaluate the impact of GLI 2021 reference equations on lung hyperinflation detection.
• To assess changes in the distribution of lung hyperinflation severity grading.
• To compare GLI 2021 findings with previous European Coal and Steel Community (ECSC) equations.

Main Methods:

• Analysis of 12,535 body plethysmography recordings (2013-2023).
• Calculation of z-scores for residual volume (RV), total lung capacity (TLC), and RV/TLC using GLI 2021 and ECSC equations.
• Assessment of lung hyperinflation severity distribution based on % predicted RV/TLC and z-scores.

Main Results:

• Severe lung hyperinflation was detected more frequently with GLI 2021 equations (27%) compared to ECSC (8.8%).
• Mild lung hyperinflation was less frequent with GLI 2021 (7%) versus ECSC (21%).
• Grading using GLI 2021 z-scores showed similar distribution to ECSC % predicted cut-offs.

Conclusions:

• GLI 2021 reference equations significantly alter lung hyperinflation grading, particularly when using % predicted cut-offs.
• A review of the lung hyperinflation severity scale is necessary for accurate classification with GLI 2021.
• Clinical practice should consider these changes for consistent and reliable diagnosis.