Table 1. Comparison of study characteristics.

	Development cohort	External validation cohort
Location	Leicester (United Kingdom)	Berlin, Düsseldorf, Freiburg, Mainz, Munich (Germany)
Climate	humid temperate maritime	humid temperate maritime/continental
Year of birth	1995–97	1990
Male sex	52%	52%
Study design	prospective cohort (birth and later)	prospective birth cohort
Recruitment	general population random sample	population-based (partly risk-enriched regarding parental allergy)
Ethnicity (mother)	81% Caucasian 19% south Asian	ethnicity unknown, predominantly Caucasian
Age at scoring (median)	2 years	3 years