Note: The risk of bias by domain corresponds to the highest risk of bias among outcomes by domain.
The overall risk of bias corresponds to the overall highest risk of bias assessed among outcomes.
| Bias | Author's judgement | Support for judgement |
| Randomization |
Low |
Quote: “Patients were randomized in a 1:1 ratio” (Report). “A web-based central randomization system will assign treatment using a fixed 1:1 allocation ratio. The randomization algorithm will prevent possible selection bias by providing random treatment assignment to each subject and prevent accidental treatment imbalances in age and site.” (Protocol)
Comment: Allocation sequence random. Allocation sequence concealed. Imbalances in baseline characteristics appear to be compatible with chance. |
| Deviations from intervention |
Low |
Quote: “Single blind”
Comment: Single-blinded study (participants blinded, personnel/carers unblinded) Deviations from intended intervention arising because of the study context: No participant cross-over. In the outpatient setting, we consider no important cointerventions of interest. Hence, no deviation arose because of the trial context. Of note, 25 patients (19 in the convalescent-plasma group and 6 in the placebo group) were ultimately admitted to the hospital during the index visit. Our analysis for the binary outcome is an intention-to-treat analysis. This method was considered appropriate to estimate the effect of assignment to intervention. Risk assessed to be low for the outcomes: Hospitalization or death. Mortality (D28). WHO score 7 and above (D28). Serious adverse events. |
| Missing outcome data |
Low |
Comment: 511 participants randomized; 498 participants analyzed.
Data available for nearly all participants randomized. Risk assessed to be low for the outcomes: Hospitalization or death. Mortality (D28). WHO score 7 and above (D28). Serious adverse events. |
| Measurement of the outcome |
Some concerns |
Comment: Method of measuring the outcome probably appropriate.
Measurement or ascertainment of outcome probably does not differ between groups. Unblinded study (outcome assessors). MORTALITY Observer-reported outcome not involving judgement. Risk assessed to be low for the outcomes: Mortality (D28). HOSPITALIZATION OR DEATH, WHO SCORE 7 AND ABOVE For these outcomes, we consider that the assessment cannot possibly be influenced by knowledge of intervention assignment. Risk assessed to be low for the outcomes: Hospitalization or death. WHO score 7 and above SERIOUS ADVERSE EVENTS The authors reported on adverse events and serious adverse events that may contain both clinically- and laboratory-detected events, which can be influenced by knowledge of the intervention assignment, but is not likely in the context of the pandemic. Risk assessed to be some concerns for the outcome: Serious adverse events. |
| Selection of the reported results |
Low |
Comment: The protocol (dated June 17th, 2020), statistical analysis plan, registry were available.
Outcomes pre-specified. Results were not selected from multiple outcome measurements or analyses of the data. Trial analyzed as pre-specified. Risk assessed to be low for the outcomes: Hospitalization or death. Mortality (D28). WHO score 7 and above (D28). Serious adverse events. |
| Overall risk of bias |
Some concerns |