Table 1.
Characteristics of the included studies (N=317)
| Characteristic | Category (N, %) | N | % |
|---|---|---|---|
| Publication type | Full report | 267 | 84.2 |
| Study protocol | 50 | 15.8 | |
| Additional information published | Appendices/online supplement | 183 | 57.7 |
| Statistical analysis plan | 17 | 5.4 | |
| Another publication (incl. study protocol) | 60 | 18.9 | |
| Other | 30 | 9.5 | |
| None | 74 | 23.3 | |
| Trial registration | Yes | 242 | 76.3 |
| No | 29 | 9.1 | |
| Unclear | 8 | 2.5 | |
| Not reported | 38 | 12.0 | |
| Location of the study participants | Africa | 19 | 6.0 |
| Asia | 54 | 16.5 | |
| Australia/New Zealand | 19 | 6.0 | |
| Europe | 123 | 39.0 | |
| North America | 198 | 62.9 | |
| South America | 15 | 4.8 | |
| Not reported | 6 | 1.9 | |
| Number of centres | Multi-centre | 193 | 61.1 |
| Single centre | 66 | 20.9 | |
| Not reported | 57 | 18.0 | |
| Population | Children only | 16 | 5.4 |
| Adults only | 265 | 83.9 | |
| Both children and adults | 28 | 8.9 | |
| Unclear | 8 | 2.5 | |
| Intervention used | Drug or biologic | 315 | 99.4 |
| Vaccine | 3 | 0.9 | |
| Surgery | 3 | 0.9 | |
| Radiotherapy | 22 | 6.9 | |
| Medical device | 0 | 0.0 | |
| Indication/ Therapeutic area | Oncology | 168 | 53 |
| Cardiology | 6 | 1.9 | |
| Vascular and hematology | 8 | 2.5 | |
| Virology | 16 | 5.0 | |
| Diabetes | 7 | 2.2 | |
| Others | 112 | 35.3 | |
| Duration of intervention | Single dose | 33 | 10.4 |
| 1 – 30 days | 99 | 31.2 | |
| 31 – 90 days | 53 | 16.7 | |
| 91 – 365 days | 109 | 34.4 | |
| 366 – 798 days | 18 | 5.7 | |
| More than 3 years | 2 | 0.6 | |
| Intervention duration not reported | 36 | 11 | |
| Control arm | Placebo | 84 | 26.5 |
| Active drug | 58 | 18.3 | |
| Vaccine | 2 | 0.6 | |
| Surgery | 3 | 0.9 | |
| Radiotherapy | 9 | 2.8 | |
| Medical device | 0 | 0.0 | |
| Historical control | 7 | 2.2 | |
| Standard of care | 15 | 4.7 | |
| No treatment | 13 | 4.1 | |
| No control arm | 158 | 49.8 | |
| Study design | |||
| Phase of trial | Phase I | 124 | 39.1 |
| Phase II | 152 | 47.9 | |
| Phase III | 56 | 17.7 | |
| Phase IV | 9 | 2.8 | |
| Not reported | 27 | 8.5 | |
| Unclear | 0 | 0.0 | |
| Description of trial design | Parallel | 171 | 54.3 |
| Cluster | 1 | 0.3 | |
| Factorial | 1 | 0.3 | |
| Other | 124 | 39.4 | |
| Unclear | 1 | 0.3 | |
| Not reported | 17 | 5.4 | |
| Platform trial | Yes | 8 | 2.5 |
| No | 307 | 96.8 | |
| Unclear | 2 | 0.6 | |
| Blinded | Yes | 104 | 32.8 |
| No | 204 | 64.4 | |
| Unclear | 9 | 2.8 | |
| Participants were provided some compensation | Yes | 5 | 1.6 |
| No | 116 | 36.7 | |
| Unclear | 14 | 4.4 | |
| Not reported | 181 | 57.3 | |
| Conflicts of Interest were declared | Yes | 208 | 65.6 |
| No | 85 | 26.8 | |
| Unspecified | 24 | 7.6 | |
| Funding source was declared | Yes | 266 | 83.9 |
| No | 44 | 13.9 | |
| Unclear | 7 | 2.2 | |
| Funder type | Government | 95 | 35.7 |
| Academic or research institute | 63 | 23.7 | |
| Private | 74 | 27.8 | |
| Industry | 131 | 49.2 | |
| Unclear | 4 | 1.5 | |
| Other | 11 | 4.1 | |