Choice affects evaluation of spirometric data
Predicted values for spirometric indices vary with the prediction equation used; the scatter about the predicted value also varies. On that account occasionally the assessment of a set of data will vary with the prediction equations used. This is most likely to occur if the data are at a transitional zone between for example ‘normal’ and mild obstruction, or a similar situation. Therefore the sensitivity, specificity and the predictive value of a test may be influenced by the choice of reference values.
An example
Girl with cystic fibrosis, standing height 164 cm, 15 year.
FEV1 = 2.18 L, FVC
= 2.73 L, FEV1%FVC
= 80%.
| Author | Assessment according to SpirXpert software |
| Knudson | Within normal limits. |
| Quanjer | Mild airway obstruction, FVC too low. |
| Wang | FEV1%VC within normal limits but VC too small. |
| Zapletal | FEV1%VC within normal limits but VC too small. |
The SpirXpert software allows you to quickly switch between a large number of prediction equations for adults, and similarly those for children and adolescents.
See als:
Reference values for children and adolescents
Reference values for adults
SpirXpert software