Adopting universal lung function reference equations
Authors: Maureen P. Swanney, Martin R. Miller
Journal: European Respiratory Journal (2013)

Adopting the GLI 2012 lung function reference equations is an essential and urgent task for laboratories worldwide http://ow.ly/nIoykSince the dawn of spirometry and testing lung function [1,2], clinicians have been aware that the values obtained from testing an individual's lung function can reflect the effects of lung diseases, and that this can be helpful with regard to all aspects of disease prevention and management.It was also recognised that the values obtained were also a reflection of the subject's sex, age and height; so to maximise the clinically relevant signal from the tests these aspects first needed to be taken into account.Studies were then undertaken to record lung function in subjects free from disease and free from the effects of tobacco smoke in order to have reference ranges of lung function.Clinicians have had to decide which of the many available prediction equations to use for their patients, realising that the different equations might lead to different judgements about the results obtained, because predicted values might vary by as much as 1 L for forced expiratory volume in 1 s (FEV1) [3].Guidance in this choice has been based on the reference population being appropriate for the patients and the equipment used for recording the lung function being equivalent.Other considerations include the age span of the reference population and the statistical approach used to derive the various predicted equations.Many European centres used the equations derived for the European Community for Steel and Coal (ECSC) [4].However, it was still evident that different hospitals in a given locality might use very different prediction equations [5], meaning a patient's outcome might vary depending on which hospital they were tested at.The Global Lung Initiative (GLI) was set up by the European Respiratory Society in 2010 with the remit to produce spirometry prediction equations that spanned all ages and could be used globally.These equations (GLI 2012) have been successfully produced [6] to the benefit of patients worldwide.Great credit should be given to the team that worked diligently to deliver these on time.Since the publication of the GLI 2012 prediction equations there have been validation studies undertaken in a wide range of ethnicities in British children [7] and in an Australasian population between 4-80 years [8], and these have shown that the GLI 2012 equations were appropriate.In this issue of the European Respiratory Journal, QUANJER et al. [9] outline the possible effect that changing to the GLI 2012 equations might have in clinical practice.In this study, the authors compared hospital spirometry data in adults from Australia and Poland using the GLI 2012, ECSC and National Health and Nutrition Examination study (NHANES III) [10] prediction equations.The authors found that the GLI 2012 equations gave predictions similar to NHANES III values but were higher than ECSC.While there was little difference in identifying an obstructive spirometric pattern, the frequency of a restrictive pattern was higher when using GLI 2012 compared to ECSC and lower when using NHANES III.