| Resource | N |
| MEDLINE | 6863 (6702 trials 161 SR) |
| Embase | 2133 (1962 trials 171 SR) |
| CENTRAL | 1491 |
| Epistemonikos | 76 |
| ClincialTrials.gov | 594 |
| ICTRP | 112 |
| Other sources | 3 |
| Total | 11,272 |
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