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| Characteristic | Number of studies | |
| Overall | 318 | |
| Publication format | ||
| Full text | 181 | |
| Letter to the editor/research letter | 110 | |
| Preprint | 27 | |
| Study design | ||
| Randomised controlled trial | 7 | |
| Prospective cohort study | 203 | |
| Retrospective cohort study | 47 | |
| Registry or surveillance system | 15 | |
| Cross‐sectional study | 32 | |
| Case‐control study | 8 | |
| Diagnostic test accuracy study | 1 | |
| Mixed | 5 | |
| Centres | ||
| Single centre | 165 | |
| Multiple centres | 146 | |
| Not reported | 7 | |
