Box-and-whisker plot of the plasma concentration of soluble receptor for advance glycation end products (sRAGE) in the study sample (n = 401). No airflow obstruction, no emphysema (n = 201). Airflow obstruction, no or mild emphysema (n = 119). Airflow obstruction, moderate emphysema (n = 56). Airflow obstruction, severe emphysema (n = 25). Line in box: median. Box height: interquartile range. Whiskers: 10th and 90th percentile. P < 0.001 by Mood's median test.