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. 2019 Apr 26;12:3139–3160. doi: 10.2147/OTT.S196684

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© 2019 Sun et al.

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(A) Risk of bias summary: review of authors’ judgments about each risk of bias item for included studies. (B) Risk of bias graph: review of authors’ judgments about each risk of bias item presented as percentages across all included studies. Each color represents a different level of bias: red for high-risk, green for low-risk and yellow for unclear-risk of bias.