Clinical characteristics of the subjects involved in the studies.

All values are represented as median values with ranges in parentheses. Ex –smokers = not smoking for at least one year. FEV1 % predicted = Forced Expiratory Volume in 1 second as percentage of predicted value; FVC = Forced Vital Capacity. Stage means severity of COPD according to GOLD criteria. Statistical significance determined by a kruskall-wallis ANOVA followed by Dunn's multiple comparisons test or a two-way student's t-test for unpaired observations.
*p<0.05,
**p<0.01,
***p<0.001 compared to Control group and
#p<0.05 compared to individuals with COPD stage II.