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.
Age-stratified incidence rates by the Global Initiative for Chronic Obstructive Lung Disease (GOLD) category.
Abbreviations: GOLD A, low symptoms, low risk; GOLD B, high symptoms, low risk; GOLD C, low symptoms, high risk; GOLD D, high symptoms, high risk.
