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.
Blue bar = total number of studies evaluated, with darker shade indicating the subset of studies included in the meta-analysis.
Pooled OR (95%CI) = pooled odds ratio with 95% confidence interval, estimated using extracted data from published studies.
* = Reference age 1–11 years.
^ = Fixed effects model used.
