doi:10.1136/ bmjopen-2021-055742 ►Prepublication history for this paper is available online. To view these files, please visit the journal online (http://dx.doi. org/10.1136/bmjopen-2021- 055742). LW and JT contributed equally. LW and JT are joint first authors. Received 24 July 2021 Accepted 27 May 2022 For numbered affiliations see end of article. Correspondence to Professor Weiqi Nian; nwqone@ gmail. comProtocol © Author(s) (or their employer(s)) 2022.