"Anyone would think your critics have a language bias!" wrote jargoyle.
In conducting systematic reviews, international collaboration in the area where language bias might occur could be a practical and feasible solution for minimizing language bias.
The search and collection of non-English language papers is important to minimize language bias [29].
In addition, excluding Japanese studies may introduce a language bias and lead to erroneous conclusions.
Finally, as we only include studies written in English, there may be some language bias in our study.
Articles not written in English were excluded, rather than not included, to ensure that the risk of language bias could be assessed [35,36].
For discrepancies found in the coverage of disease areas, Japanese studies could serve as supplementary information for the conclusions or recommendations of international assessments to prevent language bias, since international assessments do not include most Japanese studies.
It should be noted that although we tried to include local journals as well (if found by searching), there might be still many studies ruled out in this meta-sample due to the language bias.
One could argue that language bias prevents publication by researchers from these countries in major international journals [24].
