Study Population
Asthmatic children aged three to 10 years, who presented to our clinic were enrolled consecutively. Asthma was diagnosed according to GINA guidelines with recurrent bronchial obstruction findings and clinical or lung function test reversibility with inhaled bronchodilator treatment8.
Inclusion Criteria were 1) age three to 10 years 2) diagnosed or followed up with asthma 3) no bronchodilator use during the last one week. Exclusion criteria were 1) asthma exacerbation during the last one week 2) diagnosis of CF, immunodeficiency or bronchiectasis that may change lung function tests 3) premature birth.
Sample size was calculated based on the R values of the IOS measurements; We expected to have a 1:3 ratio of overweight: normal weight ratio in the group, when we predicted a standard deviation (SD) of 0.2 and minimal effect size of 0.1, the sample size required was 168 to get a power of 80%.