Statistical analysis
The data were analyzed using IBM SPSS Statistics for Windows, version
25.0 software (IBM Corp., NY, U.S.A.). Descriptive statistics are
presented as numbers and proportions or medians, with 25–75%
interquartile ranges (IQRs). The Mann–Whitney U -test was used
for comparisons of continuous variables. Logistic regression was used
for both univariate and multivariate analyses of categorical variables,
and the results were presented as odds ratios (ORs), with their 95%
confidence intervals (95% CIs). Multivariate models for the risk of
current asthma were adjusted for current and early-life confounding
factors, when appropriate. The current confounders were sex and current
daily smoking. The early confounders were age at the time of index
hospital admission (< 12 or ≥ 12 months), presence of
household pets, or presence of pets in day care and passive smoke
exposure during infancy.