[The new reference equations of the Global Lung function Initiative (GLI) for pulmonary function tests]

Area of Science:

• Pulmonary Medicine
• Respiratory Physiology
• Medical Statistics

Background:

• Previous pulmonary function test (PFT) reference equations had significant limitations.
• Weak subject sampling, inefficient age-based models, and age-group specific equations hindered accuracy.
• Expressing results as a percentage of predicted value lacked statistical significance indication.

Purpose of the Study:

• To establish new, improved reference equations for PFTs.
• To address the shortcomings of existing PFT reference equations.
• To develop equations applicable across wide age ranges and diverse ethnic groups.

Main Methods:

• Utilized large, representative reference populations for equation development.
• Employed a flexible statistical model without a priori age-evolution assumptions.
• Developed a single equation for each PFT applicable across all ages.

Main Results:

• The Global Lung Initiative (GLI) established new PFT reference equations in 2012 (spirometry) and 2017 (TLCO).
• GLI equations provide a reference value, lower limit of normal, and z-score.
• These incorporate age, sex, size, and ethnicity for individualized assessments.

Conclusions:

• GLI reference equations offer a more precise and statistically robust method for PFT interpretation.
• The new equations ensure continuity across pediatric and adult age groups.
• Ongoing work addresses representation for underrepresented ethnic groups and extreme age/size values.