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).
|FEV1 (litres)||FVC (litres)||FEV1/FVC (ratio)|
|Lower Limit of Normal|
|Upper Limit of Normal|
The GLI software packages are to be used for research, education, training and validation of implementation in software, and not for use in patient treatment. For treatment/diagnostic purposes, please use the GLI reference equations as implemented by medical device companies.
Stanojevic S, Wade A, Stocks J, et al. Reference ranges for spirometry across all ages. A new approach. Am J Respir Crit Care Med 2008; 177: 253–260.
Quanjer PH, Stanojevic S, Cole TJ, et al. and the ERS Global Lung Function Initiative. Multi-ethnic reference values for spirometry for the 3-95 years age range: the Global Lung Function 2012 equations. Eur Respir J 2012; 40: 1324-1343.