Data Extraction and Quality Assessment
Two investigators (J.X. and W.L.) extracted the following data from the
identified studies: full title, first author, publication year, study
design, follow-up period, sources of patient and participant, the number
of asthma patients, T1DM patients, and OR/RR/HR with 95%CI. The quality
of eligible literature was assessed using the Newcastle-Ottawa Scale
(NOS), a tool recommended by the Cochrane Collaboration for the quality
assessment of observational studies.12 Eligible
studies with scores of 0-3, 4-6, and 7-9 were considered as low,
moderate, and high quality, respectively. Disagreements between the
investigators in data extraction and quality assessment were resolved by
consensus, and if consensus could not be reached, a third investigator
(X.Z.) was consulted for a final decision.