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 |
Some concerns |
Quote: “Following signing an informed consent, patients were randomized to either HBOT or control arms in a 2:1 ratio according to a randomization table, supervised by a blinded researcher.” Comment: Allocation sequence probably random. Unclear allocation concealment. |
| Deviations from intervention |
Some concerns |
Pre-print: “All laboratory personnel were blinded to participant characteristics and clinical information.”
Comment: Unclear blinding (participants and personnel/carers) Deviations from intended intervention arising because of the study context: 1 participant in the control group received intervention treatment. There was administration of co-interventions of interest but the proportion between arms wasn't clear. This deviation could affect the outcome. Nevertheless, this domain was rated as some concern as it is impossible to distinguish deviation because of trial context and deviation because of intervention effect. Data for the outcome were analyzed using intention-to-treat analysis. This method was considered appropriate to estimate the effect of assignment to intervention. Risk assessed to be some concerns for the outcomes: Mortality (D28). Clinical improvement (D28). Adverse events. Serious adverse events. |
| Missing outcome data |
High |
Comment: 29 participants randomized; 25 participants analyzed.
Data not available for all or nearly all participants randomized. No evidence that the result is not biased. Reasons: 1 participant did not complete post HBOT tests and 3 discontinued intervention. All in the intervention arm. Missingness could depend on the true value of the outcome Likely that missingness depended on the true value of the outcome (imbalance between arms) Risk assessed to be high for the outcomes: Mortality (D28). Clinical improvement (D28). Adverse events. 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. Unclear blinding (outcome assessor). MORTALITY Mortality is observer-reported outcome not involving judgement. Risk assessed to be low for the outcomes: Mortality (D28) CLINICAL IMPROVEMENT Clinical improvement (defined as discharge) requires clinical judgement and could be affected by knowledge of intervention receipt, but it not considered likely to in the context of a pandemic. Risk assessed to be some concerns for the outcomes: Clinical improvement (D28). ADVERSE EVENTS and 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 outcomes: Adverse events. Serious adverse events. |
| Selection of the reported results |
Some concerns |
Comment: The prospective registry was available (dated April 24th, 2020)
MORTALITY, ADVERSE EVENTS. Outcome 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 outcome: Mortality (D28). Adverse events. CLINICAL IMPROVEMENT, SERIOUS ADVERSE EVENTS Outcome not pre-specified No information on whether the result was selected from multiple outcome measurements or analyses of the data. Trial probably not analyzed as pre-specified. Risk assessed to be some concerns for the outcome: Clinical improvement (D28). Serious adverse events. |
| Overall risk of bias |
High |