Table 2.
Assessment of risk of bias of the randomised trials using the cochrane collaboration’s tool
| First author | Bias | Authors’ judgement | Support for judgement |
|---|---|---|---|
| Sterodimas et al. (2011) | Random sequence generation (selection bias) | Unclear risk | No information regarding the randomisation technique is mentioned |
| Allocation concealment (selection bias) | High risk | No allocation concealment is done. | |
| Blinding of participants and personnel (performance bias) | Unclear risk | No blinding of participants mentioned | |
| Blinding of outcome assessment (detection bias) | Unclear risk | No information given | |
| Incomplete outcome data (attrition bias) | Low risk | All outcome data reported | |
| Selective reporting (reporting bias) | Low risk | The study protocol is available and all data is reported in the pre-specified way. | |
| Other bias | Unclear risk | Similar baseline characteristics not mentioned | |
| Koh et al. (2012) | Random sequence generation (selection bias) | Unclear risk | No information regarding randomisation technique is mentioned |
| Allocation concealment (selection bias) | Unclear risk | No information regarding allocation concealment is mentioned. | |
| Blinding of participants and personnel (performance bias) | Unclear risk | No information given | |
| Blinding of outcome assessment (detection bias) | Unclear risk | No information given | |
| Incomplete outcome data (attrition bias) | High risk | Standard deviation for volume differences is missing | |
| Selective reporting (reporting bias) | Low risk | Study protocol available with no missing outcomes. | |
| Other bias | Low risk | Similar baseline characteristics | |
| Kølle et al. (2013) | Random sequence generation (selection bias) | Low risk | allocation sequence was generated using an online randomisation generator |
| Allocation concealment (selection bias) | Low risk | Allocation was concealed by a person unrelated to the trial management group and monitored by the Good Clinical Practice unit | |
| Blinding of participants and personnel (performance bias) | Low risk | “The participants, study personnel, and outcome assessors were all blinded to treatment allocation, and blinding was maintained until all data had been analysed”. | |
| Blinding of outcome assessment (detection bias) | Low risk | “The participants, study personnel, and outcome assessors were all blinded to treatment allocation, and blinding was maintained until all data had been analysed”. | |
| Incomplete outcome data (attrition bias) | Low risk | All outcome data is reported | |
| Selective reporting (reporting bias) | Low risk | Study protocol is available in the appendix | |
| Other bias | Low risk | No further biases detected | |
| Tanikawa et al. (2013) | Random sequence generation (selection bias) | Low risk | Random number generator used |
| Allocation concealment (selection bias) | Unclear risk | No information given | |
| Blinding of participants and personnel (performance bias) | Low risk | Double blinded | |
| Blinding of outcome assessment (detection bias) | Unclear Risk | No information given | |
| Incomplete outcome data (attrition bias) | Low risk | No outcome data was missing | |
| Selective reporting (reporting bias) | Low risk | Study protocol available with no missing outcomes | |
| Other bias | Low risk | No further biases detected | |
| Malik et al. (2019) | Random sequence generation (selection bias) | Low risk | Patients were selected using envelope method |
| Allocation concealment (selection bias) | Unclear risk | No information given regarding concealement | |
| Blinding of participants and personnel (performance bias) | Low risk | Patients were divided randomly using computerized methods | |
| Blinding of outcome assessment (detection bias) | Unclear risk | No mention of how outcomes were assessed | |
| Incomplete outcome data (attrition bias) | Low risk | All outcome data was reported and no patients lost to follow up | |
| Selective reporting (reporting bias) | Low risk | Study protocol available with no missing outcomes | |
| Other bias | Unclear risk | No mention of baseline characteristics between the patients |