Characteristics of all included studies
| Characteristic | Value | Proportion (%) |
| Count of eligible Studies | 415 | 100 |
| Registry | ||
| ChiCTR | 303 | 73.0 |
| ClinicalTrials.gov | 111 | 26.7 |
| ISRCTN | 1 | 0.2 |
| Registration Status | ||
| Prospective | 243 | 58.6 |
| Retrospective | 172 | 41.4 |
| Primary purpose | ||
| Prevention | 105 | 25.3 |
| Treatment | 290 | 69.9 |
| Prognosis/quality of Life | 19 | 4.6 |
| Health services research | 1 | 0.2 |
| Multicentre research | ||
| Yes | 136 | 32.8 |
| No | 273 | 65.8 |
| Unknown | 6 | 1.4 |
| Recruitment status | ||
| Not yet recruiting | 133 | 32.0 |
| Recruiting | 206 | 49.6 |
| Completed | 55 | 13.3 |
| Suspended, terminated or withdrawn | 21 | 5.1 |
| Suspended research | 34 | 8.2 |
| Estimated enrolment | ||
| Median (IQR) | 120 (240) | |
| Min, Max | 0, 29 000 | |
| Missing | 3 | 0.9 |
| No of arms | ||
| 2 arms | 284 | 68.4 |
| 3 arms | 59 | 14.2 |
| 4 arms | 31 | 7.5 |
| 5 arms | 5 | 1.2 |
| 6–10 arms | 25 | 6.0 |
| More than 10 arms | 11 | 2.7 |
| Participants | ||
| Patient | 285 | 68.7 |
| Suspected or close contact of confirmed patient | 8 | 1.9 |
| Healthy | 122 | 29.4 |
| Masking | ||
| Single/double blind | 126 | 30.4 |
| Open label | 125 | 30.1 |
| Not stated | 164 | 39.5 |
| Count of primary outcome | ||
| 0 | 3 | 0.7 |
| 1 | 186 | 44.8 |
| 2 | 101 | 24.3 |
| 3 | 49 | 11.8 |
| 4 | 28 | 6.7 |
| 5 | 14 | 3.4 |
| More than 5 primary outcomes | 34 | 8.2 |
| Median (IQR) | 2 (2) | |
| Min, Max | 0, 23 | |
| Total no of primary outcomes | 1048 | |
| Count of secondary outcome | ||
| 0 | 102 | 24.6 |
| >0 | 313 | 75.4 |
| Median (IQR) | 4 (6) | |
| Min, Max | 0, 32 | |
| Publication | ||
| None | 322 | 77.6 |
| Protocol only | 13 | 3.1 |
| Report only | 73 | 17.6 |
| Both protocol and report | 7 | 1.7 |