When defining new onset of a particular symptom, the reference
group was those children who did not have the particular symptom in
the first 2 years of life (at baseline).When defining ‘any onset’ of symptoms,
the reference group was the children who did not have any of the
three symptoms (wheeze, rhinitis, eczema) in the first 2 years of life.
When defining remission of a particular symptom, the reference
group was the children who had the particular symptom in the first
2 years of life. When defining ‘complete remission’ of symptoms, the
reference group was the children who had at least one of the three
symptoms in the first 2 years of life