1. The impact of switching to the new global lung function initiative equations on spirometry results in the UK CF Registry 
Sanja Stanojevic, Janet Stocks, Vassiliki Bountziouka, Paul Aurora, Jane Kirkby, Stephen Bourke, Siobhán B. Carr, Elaine Gunn, Ammani Prasad, Margaret Rosenfeld, Diana Bilton 
Journal of Cystic Fibrosis 
Volume 13, Issue 3, Pages (May 2014)
DOI: /j.jcf
Copyright © 2013 European Cystic Fibrosis Society. Terms and Conditions

2. Fig. 1
Predicted FEV1 and FVC for age using Knudson (dashed line) and GLI-2012 (solid line) equations. The age range was limited to <50years, due to the limited number of survivors beyond this age. Predicted values were calculated for the median height (50th centile) at each age. On average the predicted values for FEV1 and FVC were higher using GLI compared with Knudson, but this was not consistent across the age-range.
Journal of Cystic Fibrosis  , DOI: ( /j.jcf )
Copyright © 2013 European Cystic Fibrosis Society. Terms and Conditions

3. Fig. 2
Box whisker plots of Knudson–GLI differences by age in years. Whiskers (light grey) represent interquartile range, boxes (black) represent 95% CI, and outliers are shown individually. There is a clear age related bias between the equations, with the discrepancy between equations being most striking in adolescence. Note that since the predicted values for FEV1 and FVC tended to be lower using Knudson equations compared to GLI (Fig. 1), the %predicted values (calculated as [measured/predicted]∗100) tend to be overestimated.
Journal of Cystic Fibrosis  , DOI: ( /j.jcf )
Copyright © 2013 European Cystic Fibrosis Society. Terms and Conditions

4. Fig. 3
Predicted FEV1 and FVC for age using Wang–Hankinson (dashed line) and GLI (solid line) equations. The age range was limited to <50years, due to the limited number of survivors beyond this age. Predicted values were calculated for the median height (50th centile) at each age. On average the predicted values for FEV1 and FVC were higher using GLI in children compared with Wang, but similar compared with Hankinson. There was poor overlap in predicted values for the FEV1/FVC, predicted values tending to be under-estimated by Wang–Hankinson, except in males >30years of age where they were over-estimated.
Journal of Cystic Fibrosis  , DOI: ( /j.jcf )
Copyright © 2013 European Cystic Fibrosis Society. Terms and Conditions

5. Fig. 4
Box whisker plots of Wang–Hankinson–GLI differences by age in years. Whiskers (light grey) represent interquartile range, boxes (black) represent 95% CI, and outliers are shown individually. There is a clear age related bias between the equations, particularly in paediatric patients where Wang equations are applied. The %predicted FEV1/FVC was consistently over-estimated using Wang–Hankinson in males, whereas the differences were age dependent for females.
Journal of Cystic Fibrosis  , DOI: ( /j.jcf )
Copyright © 2013 European Cystic Fibrosis Society. Terms and Conditions

6. Fig. 5
Four patient examples that illustrate within-subject differences in the impact of choice of reference equation on FEV1 %predicted during serial measurements. GLI (● solid line), Knudson (■ dashed line), Wang–Hankinson (▲ dotted line).
Journal of Cystic Fibrosis  , DOI: ( /j.jcf )
Copyright © 2013 European Cystic Fibrosis Society. Terms and Conditions