The risk of methodological bias was evaluated using quantitative appraisal forms from the Johanna Briggs Institute (JBI). Studies scoring lower than six on the MAStARI instrument were excluded from the review.
Aðferðafræðileg gæði rannsókna voru metin samkvæmt MAStARI viðmiðum Johanna Briggs Institute (JBI) um tilraunarannsóknir og voru greinar sem skoruðu minna en sex stig útilokaðar.