Table 4.

Risk of bias in non-randomized studies (ROBINS-I).

Risk of Bias Domain	Creevy, 1932	Christensen, 1987
Bias due to confounding	Serious	Moderate
Bias in selection of participants into the study	Moderate	Low
Bias in classification of interventions	Serious	Low
Bias due to deviations from intended interventions	Serious	Moderate
Bias due to missing data	Serious	Low
Bias in measurement of outcomes	Moderate	Moderate
Bias in selection of the reported result	Moderate	Low
Overall bias	Serious	Moderate