Table 2:

Summary of risk bias assessment and grade of evidence

Authors, Year	Random Sequence Generation	Allocation concealment	Blinding of participants and personnel	Blinding of outcome assessment	Incomplete outcome data	Selective reporting	Grade of Evidence
Meta-analysis Studies
Domenici et al, 201631	↑	↑	↑	Unclear	↓	Unclear	Poor
Kranjcec et al, 20148	↑	↑	↑	Unclear	↓	Unclear	Fair
Porru et al, 201437	↓	Unclear	↑	Unclear	↓	↓	Fair
Other studies
Genovese et al, 201738	↓	↑	↑	↑	↓	Unclear	Poor
Phe et al, 20 1 732	↑	↑	↑	↑	↓	↓	Poor
DelPopolo et al, 201816	↑	↑	↑	↑	↑	Unclear	Poor
Efros et al, 20 1 030	↑	↑	↑	↑	↑	Unclear	Poor
Marchiori et al, 201733	↑	↑	↑	↑	↑	Unclear	Poor

Risk of bias graded as either high (↑), low (↓) or unclear