Flowchart

Last update : 2020-08-06

Electronic databases
(n=36783, from PubMed)
Archives and curated websites
(n = 5870 from MedRxiv, ChinaXiv)
Other sources
(n = 29)

Records after duplicates removed
(n=28535)



Records screened
(n = 34434)


Records excluded
(n = 33881)

Full-text articles assessed for eligibility
(n = 553)


Full-text articles excluded:
(n = 293)

Randomized Controlled Trials
(n=33)

Eligible non-randomized studies
(n=17)

Other observational studies
(n=227)