Search Method
This meta-analysis was conducted in term of the Preferred Reporting
Items for Systematic Review and Meta-Analysis (PRISMA) Updating
guidance(16). This research was registered in PROSPERO and ID was
CRD42021281619. Two researchers (xing cao and yafei wang) searched in
PubMed, EMBASE, and Cochrane Library independently for related
electronic literatures without language restrictions (updated in
September 2021). The comprehensive search strategy combined Medical
Subject Headings (MeSH) terms with Entry Terms. Take PubMed for example,
Proton Pump Inhibitors is MeSH, the Entry Terms in PubMed included the
following: “Inhibitors, Proton Pump,” “Proton Pump Inhibitor,”
“Inhibitor, Proton Pump,” and “Pump Inhibitor, Proton.” The same
search strategy was applied in immune checkpoint inhibitors and merged
two results by “AND”. The detailed
search formula was presented in supplementary due to its prolixity.