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. 2019 Feb 21;21(2):e12997. doi: 10.2196/12997

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©Zhilian Huang, Monika Semwal, Shuen Yee Lee, Mervin Tee, William Ong, Woan Shin Tan, Ram Bajpai, Lorainne Tudor Car. Originally published in the Journal of Medical Internet Research (http://www.jmir.org), 21.02.2019.

This is an open-access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work, first published in the Journal of Medical Internet Research, is properly cited. The complete bibliographic information, a link to the original publication on http://www.jmir.org/, as well as this copyright and license information must be included.

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Risk of bias summary: review authors' judgement about each risk of bias item for each included study. The symbol "+" indicates a low risk of bias, "?" indicates unclear risk of bias and "-" indicates a high risk of bias. The methodology of 2 studies (Crenshaw 2010 and Billue 2012) are duplicated with (Estrada 2011) and not presented in this figure.