Table 2.
The NOS quality of included studies.
| Study | Selection | Comparability | Outcome | Total | Quality | ||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| REC | SNEC | AE | DO | SC | AF | AO | FU | AFU | |||
| Alharthy et al. 11 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 1 | 8 | High |
| Alkouh et al. 12 | 1 | 1 | 1 | 1 | 0 | 0 | 0 | 1 | 1 | 6 | Moderate |
| Costa et al. 9 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 1 | 1 | 8 | High |
| COVID-ICU group 13 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 9 | High |
| Duan et al. 14 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 9 | High |
| Fernández et al. 15 | 1 | 1 | 1 | 1 | 0 | 0 | 1 | 1 | 1 | 5 | Moderate |
| Franco et al. 16 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 8 | High |
| Gaulton et al. 17 | 1 | 1 | 1 | 1 | 1 | 0 | 1 | 0 | 1 | 7 | Moderate |
| Ghani et al. 18 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 1 | 1 | 8 | High |
| Gough et al. 19 | 1 | 1 | 1 | 1 | 0 | 0 | 1 | 0 | 1 | 6 | Moderate |
| Mahroof et al. 21 | 1 | 1 | 1 | 1 | 0 | 0 | 1 | 0 | 1 | 5 | Moderate |
| Menga et al. 22 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 0 | 0 | 6 | Moderate |
| Nadeem et al. 23 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 0 | 1 | 7 | Moderate |
| Pearson et al. 25 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 1 | 7 | Moderate |
| Ranieri et al. 27 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 9 | High |
| Rodrigues Santos et al. 28 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 1 | 8 | High |
| Shoukri 29 | 1 | 1 | 1 | 1 | 1 | 0 | 1 | 0 | 1 | 7 | Moderate |
| Sykes et al. 30 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 1 | 8 | High |
| Wendel Garcia et al. 31 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 1 | 0 | 7 | Moderate |
| Wendel Garcia et al. 32 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 1 | 8 | High |
AE, ascertainment of exposure; AF, study controls for any additional factors; AFU, adequacy of follow-up of cohorts (⩾90%); AO, assessment of outcome; DO, demonstration that outcome of interest was not present at start of study; FU, follow-up long enough for outcomes to occur; REC, representativeness of the exposed cohort; SC, study controls for age, sex; SNEC, selection of the non-exposed cohort.
‘1’ means that the study is satisfied with the item and ‘0’ means the opposite situation.