Fig 1.
Coiling AOR scattergram showing 19 prospective and retrospective studies. The average AOR was 8.8% (95% CI 7.6%–10.1%). Numbers correlate with study number given in Table 2.
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.