Statistical analysis
Categorical variables are expressed as number (percentage), and
continuous variables are expressed as either mean (standard deviation)
or median (range) when appropriate. Univariate and multivariate analyses
were used to identify independent associations between demographics and
clinical characteristics with AAI prescription. The chi-squared
statistic and independent samples t-test were used to compare
categorical and continuous variables between groups in univariate
analysis, respectively. Variables with a P value of 0.1 or less
from univariate analysis were included in multivariate logistic
regression to determine which variables were independently associated. AP value of less than 0.05 was considered statistically
significant for the multivariate analysis. SPSS Statistics version 20
(IBM, Armonk, NY, USA) was used for all analyses. The incidence rates
were calculated by the number of patients divided by the number of total
estimated population of Hong Kong between 2009 and 2019. The AAI
prescription rates were calculated by dividing the number of AAI
prescriptions by the number of patients with anaphylaxis. Population
statistics from the Census & Statistics Department (Hong Kong
Government) were extracted for calculations11. Our
Census used 19 years old as the cut-off age for pediatric population,
thus estimates for the breakdown of pediatric and adult anaphylaxis
incidence rates were calculated using population data for <20
and ≥20 years, respectively. This study was reviewed and approved by the
Institutional Review Board of the Joint Chinese University of Hong Kong
– NTEC Clinical Research Ethics Committee.