Table 4.

Risk of bias of included studies (Semiexperimental study)

Author	Firouzbakht et al. (2015)	Gurkan & Ekşi (2017)	Isbir et al. (2017)	Karabulut et al. (2016)	Serçekuş & Başkale. (2015)	Taheri et al. (2014)
Bias due to confounding	Moderate	Moderate	Serious	Serious	Moderate	Moderate
Bias in the selection of participants	Serious	Serious	Serious	Serious	Serious	Low
Bias in the classification of interventions	Low	Low	Low	Low	Low	Low
Bias due to deviations from intended interventions	Low	Low	Low	Low	Low	Low
Bias due to missing data	Serious	Moderate	Low	Serious	Moderate	Moderate
Bias in the measurement of outcomes	Serious	Serious	Serious	Serious	Serious	Serious
Bias in the selection of reported result	Serious	Low	Moderate	Low	Moderate	Moderate
Overall	Serious	Serious	Serious	Serious	Serious	Serious

Low: Low risk of bias (the study is comparable to a well-performed randomized trial concerning this domain); Moderate: Moderate risk of bias (the study is sound for a non-randomized study concerning this domain but cannot be considered comparable to a well-performed randomized trial); Serious: Serious risk of bias (the study has some important problems)