| Bias | Author's judgement | Support for judgement |
| Confounding |
Moderate |
Comment: Some baseline imbalances for comorbidities. In the propensity score matched sample, all confounders of interest are balanced (see Table 1) Ethnicity is not controlled for and not reported. |
| Selection of participants into the study |
NI |
Comment: It is unclear when patients were included in the study (according to Table 1, study inclusion does not coincide with hospital admission). The delay between admission and study inclusion is mean 3 days (SD 11). |
| Intervention classification |
Low |
Quote: Patients were compared between two group: those who received 84 tocilizumab (a single intravenous injection, 400 mg) and those who did not (control group). Comment: data were collected from clinic records. Treatment groups were classified using clearly defined criteria (receipt vs non receipt of a single tocilizumab dose). |
| Deviation from intended intervention |
Low |
Comment: Use of concomittant medication post-admission is presented in Table 1. Corticosteroids, antivirals, antibiotics, and ICU care are balanced between-arms in the propensity score matched sample. Risk assessed to be low for the outcomes: time to death. Time to WHO clinical progression scale score 7 and above. |
| Missing data |
Low |
Comment: No participants were excluded due to missing outcome data or missing data on other variables needed for the analysis. One patient was not included in the study due to missing data on intervention status. Risk assessed to be low for the outcomes: time to death. Time to WHO clinical progression scale score 7 and above. |
| Measurements of outcomes |
Low |
Comment: Observer-reported outcome (death). Risk assessed to be low for the outcomes: time to death. Time to WHO clinical progression scale score 7 and above. |
| Selection of the reported results |
Moderate |
Comment: Observer-reported outcome (death). Risk assessed to be low for the outcomes: time to death. Time to WHO clinical progression scale score 7 and above. |