Table 2.

Risk of bias assessment for randomized trials.

Study	D1a	D2b	D3c	D4d	D5e	Overall
Basha et al [40]	Low	Some concerns	Low	Low	Low	Low
Benzing et al [33]	Low	Some concerns	Low	Low	Low	Some concerns
Feyzioğlu et al [38]	Low	Some concerns	Low	Low	Low	Some concerns
Hamari et al [34]	Low	High	Low	Low	Low	High
Sajid et al [50]	Some concerns	Some concerns	Low	Low	Low	Some concerns
Schumacher et al [46]	Low	Some concerns	Some concerns	Low	Low	Some concerns
Villumsen et al [51]	Low	Some concerns	Some concerns	Low	Low	Some concerns
Czech et al [39]	Low	Some concerns	Low	Low	Low	Some concerns

^aD1: bias due to the randomization process.

^bD2: bias due to deviations from intended interventions.

^cD3: bias due to missing data.

^dD4: bias in measurement of outcomes.

^eD5: bias in selection of the reported results.