Table 1.
Characteristics of the 92 Included Studiesa
| Characteristic | No. (%) of studiesb |
|---|---|
| Journal impact factor | |
| >50 | 19 (21) |
| 20-50 | 8 (9) |
| 5-20 | 65 (71) |
| Article type | |
| Original article | 54 (59) |
| Research letter | 35 (38) |
| Other (brief report or communication) | 3 (3) |
| Study design | |
| Retrospective observational | 83 (90) |
| RCT | 5 (5) |
| Prospective observational | 4 (4) |
| Study center | |
| Single-center | 51 (55) |
| Multicenter | 39 (42) |
| Unknown | 2 (2) |
| Geographic area | |
| Asia | 61 (66) |
| Europe | 16 (17) |
| North/South America | 10 (11) |
| Multicountry | 5 (5) |
| Sample size | |
| 20-100 | 36 (39) |
| 100-1000 | 45 (49) |
| >1000 | 11 (12) |
| Critically ill population | |
| Subgroup | 64 (70) |
| Full cohort | 28 (30) |
| Critical illness categories | |
| Patients admitted to the ICU | 23 (25) |
| Severe (Chinese guidelines) | 25 (27) |
| Severe (American guidelines) | 3 (3) |
| Organ injury or dysfunction | 23 (25) |
| Patients who died of COVID-19 | 18 (20) |
| Research domain | |
| Clinical characteristics | 52 (57) |
| Risk factors | 29 (32) |
| Treatment | 11 (12) |
a
COVID-19, coronavirus disease 2019; ICU, intensive care unit; RCT, randomized clinical trial.
b
Percentages may not total 100 because of rounding.