The Global Lung Function Initiative (GLI) Network: bringing the world's respiratory reference values together

Abstract

The Global Lung Function Initiative (GLI) Network has become the largest resource for reference values for routine lung function testing ever assembled. This article addresses how the GLI Network came about, why it is important, and its current challenges and future directions. It is an extension of an article published in Breathe in 2013 [1], and summarises recent developments and the future of the GLI Network.

Key points: The Global Lung Function Initiative (GLI) Network was established as a result of international collaboration, and altruism between researchers, clinicians and industry partners. The ongoing success of the GLI relies on network members continuing to work together to further improve how lung function is reported and interpreted across all age groups around the world.The GLI Network has produced standardised lung function reference values for spirometry and gas transfer tests.GLI reference equations should be adopted immediately for spirometry and gas transfer by clinicians and physiologists worldwide.The recently established GLI data repository will allow ongoing development and evaluation of reference values, and will offer opportunities for novel research.

Educational aims: To highlight the advances made by the GLI Network during the past 5 years.To highlight the importance of using GLI reference values for routine lung function testing (e.g. spirometry and gas transfer tests).To discuss the challenges that remain for developing and improving reference values for lung function tests.

Figure 1

Predicted values for a, b) FEV₁, c, d) FVC and e, f) FEV₁/FVC by sex and ethnic group. a, c, e) Males and b, d, f) females. Graphs were generated using mean height for age in Caucasians to illustrate proportional differences between ethnic groups of the same height and age; in practice, differences in height for age further affect predicted values. The rise and fall in FEV₁/FVC around adolescence is due to differential changes in FEV₁ and FVC. Reproduced from [15].

Figure 2

a) Predicted T_LCO in i) 4859 males and ii) 4851 females), b) alveolar volume (V_A) (standard temperature and pressure, dry) in i) 4793 males and ii) 4837 females) and c) carbon monoxide transfer coefficient (K_CO) in i) 4793 males and ii) 4837 females. The solid line represents the predicted values for age (assuming an average height at each) and the dashed lines represent 95% confidence limits. Prediction equations are overlaid on observed values. The average height used in children was the 50th height-for-age centile from the US Centers for Disease Control and Prevention growth charts [16] whereas in adults, the average height observed in the study population was used (172 cm in males and 162 cm in females). Reproduced from [17].