| Popis: |
The interpretation of spirometric results depends, among others, on the reference equations used and the choice of metrics. Aim: To evaluate the impact on severity classification from spirometry results using the % predicted (%p) and z-score (Zsc), both derived from the Global Lungs Initiative (GLI) 2012 equation. Methods:1,869 baseline spirometries performed at a pediatric lung function laboratory in 2018, by children 3-18 years [median12; IQR (9-15)], were reviewed. The results for defining normality were analyzed by: %p (FEV1; FEV1/FVC≥80), LLN (FEV1; FEV1/ FVC≥LLN), Zsc (FEV1; FEV1/FVC≥-1.64). Severity was classified by the FEV1%p (ATS/ERS) and by Zsc, respectively: mild (M)(≥70%; ≥-2.0), moderate (Mo)(60–69%; -2.5to−2.0), moderate to severe (MoS)(50–59%; -3to−2.5), severe(S) (35–49% −3.0to−4.0) and very severe (VS)( Results: Spirometry results were interpreted as normal by %p in 65% and by Zsc and LLN in 71% cases. Changes in severity degree between %p and Zsc occurred in 19% cases; in class M 27% (120/440) changed to normal, while 15% (68/440) worsened severity. In all other groups a change to more severe class was verified: in Mo 92% (77/84), in MoS 100% (44/44) and in S 95% (39/41). VS cases increased from 42 (%p) to 85 (Zsc). Significant differences were found in the normal, M and VS categories (p Conclusion: GLI2012 equations were intended to reduce bias associated with age, sex and race. This study showed that mild cases improved from %p to Zsc by GLI and all other classes worsened severity. %p underestimates the severity of the ventilatory disturbance when compared to Zsc. |
