GLI Spirometry Normal Values

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These Global Lungs Quanjer GLI-2012 regressions, based on NHANES, are produced using an extension of the lambda-mu-sigma (LMS) method, widely used to construct growth reference charts.

The method calculates the lower limit of normal for spirometry values as the 5th percentile of the distribution of the standard deviation score (or Z-score). LMS-derived Z-scores account for normal age-related changes in pulmonary function, including variability and skewness in reference data. The advantage of this is smoothing, partly for cosmetic reasons but also because changes of anthropometric variables over age are expected to be continuous. The modelling technique published by Stanojevic in 2008 was recognized by the European Respiratory Society (ERS) via “Task Force” status in 2010. The tables below are for mean normal value (Predicted) and the Lower Limit of Normality (LLN).