Table 4.

Risk of bias in each study as assessed using the ROBINS-I risk of bias tool.

Year	Author	Bias due to confounding	Bias in selection of participants into study	Bias in classification of exposures	Bias due to deviation from exposures	Bias due to missing data	Bias in measurement of outcomes	Bias in selection of the reported result	Overall risk of bias
1989	Swachuk	Low	No information	Low	Low	Low	Low	Low	Low
1990	Ferenczy	No information	No information	Low	Low	Low	Moderate	Low	No information
1990	Ferenczy	Low	No information	Low	Low	Low	Low	Low	No information
1994	Sood	Low	No information	Low	Low	Low	Low	Low	Low
1995	Gloster	Low	No information	Low	Low	Low	Moderate	Low	No information
2011	Weyandt	Low	No information	Low	Low	Low	Low	Low	Low
2016	Kwak	Low	No information	Low	Low	Low	Low	Low	Low
2018	Neurmann	Low	No information	Low	Low	Low	Low	Low	Low
2019	Zhou	Low	No information	Low	Low	Low	Low	Low	Low