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. 2020 Aug 25;21:172. doi: 10.1186/s12881-020-01101-2

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© The Author(s) 2020

Open AccessThis article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated in a credit line to the data.

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Fig. 1 — Flow diagram reflecting selection process of eligible studies included in meta-analysis. Initial literature search identified a total of 217 records from different online databases including Google Scholar, PubMed, ScienceDirect, Cochrane library and Embase. Of these, 155 overlapping studies (same studies that were indexed in two or more of these databases and resulted in redundant entries) were excluded, retaining 62 unique studies for further screening. Subsequent screening according to defined eligibility criteria yielded a total of 04 final studies including in this meta-analysis