There were no significant differences in age, sex, smoking status, pack years of smoking, dyspnea grade, hospital admission for COPD or the use of systemic steroids and/or antibiotics past year, lung function, GOLD grade of severity of airflow limitation, or baseline levels of biomarkers (CRP and sTNFR75) between the 4 groups. This evidence concerns the gene CRP and chronic obstructive pulmonary disease.