Abstract
Over the past 20 years, replacement of “in-house” infant lung function test (ILFT) equipment by commercial devices has resulted in equipment-specific differences in outcomes and a proposed interim correction factor was based on only 66 infants (Lum PP 2010).
Aims: To investigate differences in RVRTC data between the “in-house” RASP system and the Jaeger BabyBody device and develop prediction equations applicable to both systems.
Method: RVRTC data from healthy subjects collected using the RASP and Jaeger systems were collated from 4 centres(London, Australia, Spain and Portugal). Data were excluded if gestational age<37w; birthweight<2.5kg or FEV0.5 not achieved. Multilevel (ie. subjects nested within centres) linear regression models vs age, height, sex and equipment using suitable transformation were performed.
Results: Technically acceptable results were available from 367 healthy infants(59%boys; 92%White) on 607 tests(age range:2.7-117w; 54%Jaeger:46%RASP). When plotted according to equipment, there was good overlay for FVC and FEV0.5 but RASP FEF25-75 data were significantly higher than Jaeger data(Figs A-C). After adjusting for sex, age, height and equipment as appropriate, 95% of RASP and Jaeger data were within ±1.96z-scores(Figs D-F).
Conclusion: These new RVRTC prediction equations based on modern equipment and much larger subject numbers will facilitate improved interpretation of ILFT (Lum et al ERS 2015).
- Copyright ©ERS 2015
