Spirometry and respiratory oscillometry: Feasibility and concordance in schoolchildren with asthma.

OBJECTIVE: The purpose of this study was to describe the feasibility of respiratory oscillometry (RO) in schoolchildren with asthma, and the concordance of its results with those of spirometry, to determine its clinical usefulness. METHODS: RO and spirometry were performed in 154 children (6 to 14-year-old) with asthma, following strict quality criteria for the tests. Their feasibility (probability of valid test, time of execution, number of maneuvers needed to achieve a valid test, and perceived difficulty) was compared. The factors that influence feasibility were analyzed with multivariate methods. FEV1, FEV1/FVC, FVC and FEF25-75 for spirometry, and R5, AX and R5-19 for RO, were converted into z-scores and their concordance was investigated through intraclass correlation coefficients (ICC) and kappa indices for normal/abnormal values. RESULTS: There were no differences in the probability of obtaining a valid RO or spirometry (83.1% vs. 81.8%, p = 0.868). RO required a lower number of maneuvers [mean (SD) 4.2 (1.8) versus 6.0 (1.6), p < 0.001] and less execution time [5.1 (2.7) versus 7.6 (2.4) minutes, p < 0.001], and patients considered it less difficult. Age increased the probability of obtaining valid RO and spirometry. The concordance of results between RO and spirometry was low, and only between zFEV1 and zAX could it be considered moderate (ICC = 0.412, kappa = 0.427). CONCLUSION: RO and spirometry are feasible in children with asthma. RO has some practical advantages, but the concordance of its results with spirometry is low.