Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 1 Publication by randomized trial versus other study designs | 47 | 28928 | Risk Ratio (M‐H, Random, 95% CI) | 1.51 [1.36, 1.67] |
| 2 'Prospective' versus 'retrospective' | 30 | 14938 | Risk Ratio (M‐H, Random, 95% CI) | 1.17 [1.06, 1.30] |
| 3 Level of evidence | 7 | 3344 | Risk Ratio (M‐H, Random, 95% CI) | 1.50 [1.20, 1.86] |
