Eczema presence and eczema phenotypes
AD was operationalized as self-/guardian-reported eczema. Within each
age bracket, eczema presence was determined using three parameters:
presence, medication and treatment by a doctor. Eczema presence was
confirmed if presence was reported or if presence was denied, but either
medication or treatment were reported. Eczema was not confirmed if all
three parameters were reported negatively. Ever eczema was defined as
eczema presence in at least one of the age brackets.
Eight longitudinal phenotypes were defined, based on presence, age of
onset and persistence of eczema (Table 1) . This
stratification of eczema subclasses had been first described by
Paternoster et al. , who identified them from two longitudinal
birth cohorts using a latent-class analysis.7 Age of
eczema onset was defined as “Very early” if the first presence was
reported before the age of 6 months, “Early” between 6 months and 4
years and “Late” after the age of 4 years (Supplementary
Figure 1) . Persistence/remission of eczema was defined by assessing
eczema presence in the most recent age bracket available. When
persistence/remission could not be determined due to incomplete data,
subjects were classified into phenotypes with “no info on
persistence”. Very young children (age < 4 years at baseline)
provided no information about persistence/remission and were excluded.