An official website of the United States government
Here's how you know
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.
Loss to follow-up includes participants who moved out of the area, who could not be located, and who did not complete their 12 month interview within the study follow-up window (within 1 month of due date).