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. 2020 Oct 2;1486(1):90–111. doi: 10.1111/nyas.14506

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© 2020 New York Academy of Sciences.

This article is being made freely available through PubMed Central as part of the COVID-19 public health emergency response. It can be used for unrestricted research re-use and analysis in any form or by any means with acknowledgement of the original source, for the duration of the public health emergency.

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PRISMA flowchart for the identification and selection of observational trials. CINAHL, Cumulative Index to Nursing and Allied Health Literature; CNKI, Chinese National Knowledge Infrastructure; CQVIP, Chongqing VIP Information.