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.
Demographic data by group
Values are expressed as mean±SD [95% confidence interval], median (interquartile range) [95% confidence interval] or absolute number. *Mann-Whitney U test is used and expressed as median (interquartile range) [95% confidence interval] because of abnormal distribution. M, male; F, female; Op, operation.
