Impact of adding opioids to paravertebral blocks in breast cancer surgery patients: A systematic review and meta-analysis

Table 3 Risk of bias in included studies

Ref.	Random sequence generation	Allocation concealment	Blinding of participants and personnel	Blinding of outcome assessment	Incomplete outcome data	Selective reporting	Other bias
Mostafa et al[21]	Low risk	Low risk	Low risk	Low risk	Low risk	High risk	Low risk
Pushparajan et al[22]	Low risk	Unclear risk	Low risk	Low risk	Low risk	Low risk	Low risk
Morsy et al[23]	Unclear risk	Unclear risk	Unclear risk	Unclear risk	Low risk	Low risk	Low risk
Bhuvaneshwari et al[24]	Low risk	Unclear risk	Low risk	Low risk	Low risk	Low risk	Low risk
Omar et al[25]	Low risk	Unclear risk	Low risk	Low risk	Low risk	Low risk	Low risk
Burlacu et al[26]	Low risk	Low risk	Low risk	Low risk	Low risk	Low risk	Low risk