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.
The content is available as a PDF (899.4 KB).
Chien-Hsiang Weng, Department of Family Medicine, Brown University Warren Alpert Medical School, Providence, Rhode Island, United States.
Philip A Chan, Department of Medicine, Brown University Warren Alpert Medical School, Providence, Rhode Island, United States.
