Background: Wheezing in early life is a common disorder, with approximately 50% of children having an episode of wheezing in the first year of life. A recurrent wheeze is estimated to occur in one-third of children of preschool age and can cause significant morbidity, decrease quality of life, and increase the frequency of the use of health care services and economic costs. In young children, wheezing, either transient or persistent, can be severe and cause a poor quality of life with frequent use of health care system and economic costs.