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.
| Variables | Regression coefficient (95% CI) | P value |
|---|---|---|
| Sample size of a trial | 0.004 (−0.002 to 0.010) | 0.149 |
| Publication year | 0.05 (0.06 to 0.09) | 0.033 |
| Mortality rate of control groups | −1.29 (−2.70 to 0.13) | 0.066 |
