Rendimiento clínico de espirometría y oscilometría respiratoria para predecir crisis graves en escolares con asma

Abstract

Objective To determine the performance of spirometry and respiratory oscillometry (RO) in the prediction of severe asthma exacerbations (SAEs) in children. Methods In a prospective study, 148 children (age 6–14 years) with asthma were assessed with RO, spirometry and a bronchodilator test. Based on the findings of spirometry and the bronchodilator test, they were classified into 3 phenotypes: air trapping (AT), airflow limitation (AL) and normal. Twelve weeks later, they were re-evaluated in relation to the occurrence of SAEs. We analysed the performance of RO, spirometry and AT/AL phenotypes for prediction of SAEs by means of positive and negative likelihood ratios (LR+/LR–), ROC curves with the corresponding areas under the curve and a multivariate analysis adjusted for potential confounders. Results During the followup, 7.4% of patients had SAEs, and there were differences between phenotypes (normal, 2.4%; AL, 17.9%; AT, 22.2%, P = .005). The best area under the curve corresponded to the forced expiratory flow between 25% and 75% of vital capacity (FEF25–75): 0.787; 95% confidence interval, 0.600-0.973. Other significant areas under the curve were those for the reactance area (AX), forced expiratory volume in the first second (FEV1), the post- bronchodilator change in forced vital capacity (FVC), and the FEV1/FVC ratio. All of the variables had a low sensitivity for prediction of SAEs. The AT phenotype had the best specificity (93.8%; 95% confidence interval, 87.9-97.0), but LR+ and LR– were both significant only for the FEF25–75. In the multivariate analysis, only some spirometry parameters were significative for prediction of SAEs (AT phenotype, FEF25–75 and FEV1/FVC). Conclusions Spirometry performed better than RO for prediction of SAEs in the medium term in schoolchildren with asthma.