The GLI team have developed educational materials to help inform health professionals and patients about the GLI equations, and what they can expect when pulmonary function laboratories switch to using the GLI.
The Quanjer GLI-2012 regression equations for spirometric indices arose from the work of a Task Force of the European Respiratory Society. Their report has been endorsed by the European Respiratory Society (ERS), American Thoracic Society (ATS), Australian and New Zealand Society of Respiratory Science (ANZSRS), Asian Pacific Society for Respirology (APSR), Thoracic Society of Australia and New Zealand (TSANZ) and the American College of Chest Physicians (ACCP).
The GLI Spirometry Task Force derived continuous prediction equations and their lower limits of normal for spirometric indices. Over 160,000 data points from 72 centres in 33 countries were shared with the GLI. Eliminating data that could not be used (mostly missing ethnic group, some outliers) left 97,759 records of healthy nonsmokers (55.3% females) aged 2.5–95 yrs.
Lung function data were collated and prediction equations derived using the LMS method, which allows simultaneous modelling of the mean (mu), the coefficient of variation (sigma) and skewness (lambda) of a distribution family.
Reference equations were derived for healthy individuals aged 3–95 yrs for Caucasians (n=57,395), African–Americans (n=3,545), and North (n=4,992) and South East Asians (n=8,255). Forced expiratory value in 1 s (FEV1) and forced vital capacity (FVC) between ethnic groups differed proportionally from that in Caucasians, such that FEV1/FVC remained virtually independent of ethnic group. For individuals not represented by these four groups, or of mixed ethnic origins, a composite equation taken as the average of the above equations is provided to facilitate interpretation until a more appropriate solution is developed.
The Task Force (Global Lung Function Initiative, GLI) summarised the regression equations and lookup tables, required for implementation into software, in an Excel file. The GLI group also produced tools for calculating predicted values, their lower limits of normal and the z-scores of measured indices, as well as facilities for analysing datasets. The tools are accessible via the menu on the left. By law the use of the GLI software packages is restricted to research, education, training and validation of implementation in software; they are not to be used in patient treatment.