Main outcomes of the study population, in relation to the three study groups.

Group A: patients with at least one severe exacerbation of chronic obstructive pulmonary disease (E-COPD) in the three-year pre-index period; Group B: patients with only moderate E-COPD in the three-year pre-index period; Group C patients without E-COPD in the three-year pre-index period. The index event is not included. SD = standard deviation. 'Age and sex adjusted rate per one person-year. 1p<0.05 vs group A, 2 p<0.05 vs group B.