Methods
In the present study we enrolled children with persistent moderate to severe asthma who attended at Clínica Las Condes, Santiago and had pulmonary function tests: oscillometry followed by spirometry performed with a Vyaire Vyntus model v‐176430 spirometer-oscillometer and according to ATS/ERS guidelines (3, 4). A systematic medical history on birth weight, gestational age, history of of maternal asthma, and pre and post-natal maternal smoking was obtained. The differences between groups were calculated with the ANOVA test and the post hoc analysis with the Tukey test. The study was approved by the Ethics Committee of the institution; and informed consent was applied to the parents/guardians, and assent to the patients.