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. 2018 Oct 1;6:23–28. doi: 10.1016/j.onehlt.2018.09.002

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© 2018 Published by Elsevier B.V.

This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

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Fig. 2 — Search strategy decision tree.

A total of 7110 articles were found from PubMed (2864), MEDLINE - EMBASE (2246) and Scopus (2000) databases. See Table 2, Table 3, supporting Files 1 and 2, and Fig. 2 for detailed search histories and strategies. After removing duplicated articles, 4685 articles were found and further refinement using title and abstract skimming, a total of 185 researches have retained. Finally, a total of 19 studies which fulfil the eligibility criteria were included in the meta-analysis.