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.
(a) Cochrane risk of bias graph - assessment of non-randomized studies (b) Cochrane risk of bias summary of all non-randomized studies [14], [16], [21], [22], [23], [24], [25], [26], [27], [28], [29], [30], [31], [32], [33], [34], [35] (Risk of bias graph and summary: review authors' judgements about each risk of bias item presented as percentages across all included studies.).
