Figure 2.

COPD exacerbations during the 12-month pre- and postindex periods.

Notes: Low FEV₁% predicted defined as FEV₁ <50% predicted; high FEV₁% predicted defined as FEV₁ $50% predicted. The hierarchy applied to create type of COPD exacerbation for an exacerbation episode was: inpatient COPD exacerbation > emergency department (ED) COPD exacerbation > ambulatory COPD exacerbation. A patient could have multiple types of COPD exacerbations within the baseline (12-month preindex period) and 12-month postindex periods.

Abbreviation: FEV₁, forced expiratory volume in 1 second.