GRADE assessment
| Certainty assessment | Effect estimate (95% CI) | Certainty | ||||||
| Number of studies | Study design | Risk of bias | Inconsistency | Indirectness | Imprecision | Other considerations | ||
| Mortality | ||||||||
| 8 | Observational studies | Not serious | Not serious | Not serious | Not serious | Publication bias strongly suspected* all plausible residual confounding would reduce the demonstrated effect |
RR 0.72
(0.55 to 0.95) | LOW |
Meta-regression analysis.
*Asymmetrical funnel plot.
RR, relative risk.