AECOPD patients using in-hospital antibiotics differed from patients not using in-hospital antibiotics regarding patient-related variables (age, BMI, diabetes mellitus, cancer and chronic kidney disease), clinical variables (FEV1% predicted, sputum volume and purulence, body temperature, recent hospitalization and bronchiectasis), treatment-related variables (maintenance inhaled corticosteroids (ICS), theophylline and azithromycin) and laboratory results (CRP levels, peripheral blood leucocyte, neutrophil and eosinophil counts, and arterial blood pH). This evidence concerns the gene CRP and chronic kidney disease.