Figure 2.
Correlation between the cumulative dose of methacholine (PD20) and the score of COPD symptoms questionnaire (rs=−0.76, P=0.005) (A), and the number of exacerbations in the previous year (rs=−0.59, P=0.021) (B).
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.