Data extraction
Initially, at least two authors (XSY, NSM, and ZCL) independently
screened the records on titles and abstracts. Any relevant studies were
included for full-text assessment. Duplicates were removed if the same
study population was presented in different publications, and the
publication with the most comprehensive dataset was included. If there
are overlaps of study population in different publications and different
parts could fit into various analyses, both publications were included.
The following data were collected: author, publication year, age, sex,
study design, assessment of rhinitis and urticaria, number of patients
in total, number of rhinitis patients, number of rhinitis patients with
urticaria, number of controls, number of controls with urticaria, number
of urticaria patients, number of urticaria patients with rhinitis, and
number of controls with rhinitis. Detailed extracted data of all
included studies are presented in Supplementary Table 2. All steps of
data extraction were performed by at least two authors, and any
potential disagreements were resolved by a reviewer (PYJ).