| Study |
Bias |
| Randomisation process |
Deviations from intended interventions |
Missing outcome data |
Measurement of the outcome |
Selection of the reported results |
Overall |
| Authors' judgement |
Support for judgement |
Authors' judgement |
Support for judgement |
Authors' judgement |
Support for judgement |
Authors' judgement |
Support for judgement |
Authors' judgement |
Support for judgement |
Authors' judgement |
Support for judgement |
| Agarwal 2020 |
Low risk of bias |
The allocation sequence was random and concealed and there were no differences between intervention groups suggesting a problem with the randomization process. |
Some concerns |
Five participants in convalescent plasma arm and four in control arm did not receive the allocated intervention and this is probably a deviation from the intended intervention that arose because of the trial context. According to the study, a per protocol analysis was performed for this secondary outcome, but there was no potential for a substantial impact (on the result) of the failure to analyse randomized participants. |
Low risk of bias |
Data for this outcome was available for 451 out of 451 participants included in the per protocol analysis. Data of eight participants in the convalescent plasma arm and of five participants in the control arm were missing. |
Low risk of bias |
The measurement of the outcome was appropriate and it is unlikely that it differed between intervention groups. The outcome assessors were aware of the intervention received, but it is unlikely that knowledge of intervention received could have affected outcome measurement. |
Some concerns |
There was a trial register entry, which provided details of the pre‐specified outcomes, but "need for invasive ventilation" was not pre‐specified at trial registration. |
Some concerns |
For this outcome "Clinical worsening: Need for invasive mechanical ventilation", there is a low risk of bias from the randomization process, missing outcome data and measurement of the outcome. However, there are some concerns for bias due to deviations from intended interventions and for bias in selection of the reported result. |
| AlQahtani 2020 |
Low risk of bias |
Participants were block randomized by computer‐generated random numbering in a 1:1 ratio to receive either convalescent plasma in addition to the standard therapy or standard of care alone and the allocation sequence was concealed. There are no baseline differences that would suggest a problem with randomisation. |
Low risk of bias |
Both participants and those delivering the intervention were aware of intervention received, but there were no deviations from intended interventions and the analysis was appropriate. |
Low risk of bias |
Data for this outcome was available for all 40 participants randomized. |
Low risk of bias |
The measurement of the outcome was appropriate and it is unlikely that it differed between intervention groups. The outcome assessors were aware of the intervention received, but it is unlikely that knowledge of intervention received could have affected outcome measurement. |
Low risk of bias |
The data that produced this result was analysed in accordance with the pre‐specified analysis plan and the outcome was reported as planned in the protocol. |
Low risk of bias |
For the outcome "Need for invasive mechanical ventilation", there was a low risk of bias for all the domains. |
| Horby 2021 |
Low risk of bias |
Participants were randomized through web‐based simple randomization with allocation concealment in a 1:1:1 ratio to a platform trial in a factorial design, receiving either convalescent plasma in addition to the standard therapy or standard of care alone. There are no baseline differences that would suggest a problem with randomisation. |
Low risk of bias |
Both participants and those delivering the intervention were aware of intervention received, but there were no deviations from intended interventions and the analysis was appropriate. |
Low risk of bias |
Data for this outcome was available for all participants not on invasive mechanical ventilation at baseline, a total of 10,901 out of 11,558 participants randomized. |
Low risk of bias |
The measurement of the outcome was appropriate and it is unlikely that it differed between intervention groups. The outcome assessors were probably not aware of the intervention received. |
Low risk of bias |
The data that produced this result was analysed in accordance with the pre‐specified analysis plan and the outcome was reported as planned in the protocol. |
Low risk of bias |
For the outcome "Need for invasive mechanical ventilation", there was a low risk of bias for all the domains. |
| Simonovich 2020 |
Low risk of bias |
Participants were randomized through a randomization program (REDCap) in a 2:1 ratio to receive either convalescent plasma or a placebo. The allocation sequence was random and concealed. There are no baseline differences that would suggest a problem with randomisation. |
Low risk of bias |
Both participants and carers and people delivering the intervention were unaware of the assigned intervention received and the analysis was appropriate. |
Low risk of bias |
From the 334 participants randomized, data was available for 228 participants in the convalescent plasma group and 105 participants in the placebo group. The data of one participant in control group was missing, due to withdrawal of consent after randomisation and therefore the participant was excluded from the analysis. |
Low risk of bias |
The outcome measurement is an appropriate measure and it is unlikely that the measurement differed between intervention groups. The outcome assessors were not aware of the intervention received. |
Low risk of bias |
The data that produced this result was analysed in accordance with the pre‐specified analysis plan and the outcome was reported as planned in the protocol. |
Low risk of bias |
For the outcome "Clinical worsening: Need for invasive mechanical ventilation", all the domains have a low risk of bias. |
