Assessing pulmonary function in 3-year-old children using respiratory oscillometry: a validation study in rural Guatemala

Background Respiratory oscillometry may be important for understanding early-Iife lung function, but evidence supporting its use in Guatemala is limited. We assessed the validity and reliability of respiratory oscillometry in three-year-old Guatemalan children and whether these improve with quality control (QC). Methods We measured respiratory oscillometry resistance and reactance at 7 Hertz (R7 and X7), the frequency dependence of resistance (R7-R19), and the area of reactance (AX) in 666 Household Air Pollution Intervention Network trial children during home visits. Standard measurement QC removed artifacts using commercial software and selected the first three measurements with an R7 coefficient of variation ≤15%. Alternative investigators’ methods varied in QC procedures. We evaluated validity as the proportion of variability in tests predicted by the child's height (R 2 ) and, in a subset of 50 children, as agreement with test results after manual QC by a pediatric pulmonologist. Reliability was assessed by the intraclass correlation (ICC) of repeated tests. Results We collected oscillometry in 542 children. Height explained 5–15% of the variability in R7, X7, and AX, but none in R7-R19. The correlation between standard and manually cleaned tests ranged from 0.66 to 0.97, depending on the parameter. Among first-tests, between-day ICCs using the standard method for R7, R7-R19, X7, and AX were 0.68, 0.45, 0.60, and 0.71, respectively, and the best between-day ICCs using an alternative method were 0.75, 0.57, 0.69, and 0.74, respectively. Discussion We demonstrated good validity and reliability of respiratory oscillometry measurements collected at home from pre-school-aged Guatemalan children. Investigators’ automated QC methodology performed equally or better than standard methodology.