Table 2

Variable definitions and categorisation

VariablesDefinitions
Highest level of maintenance therapy
(ICS, non-ICS)

  • Therapy prescribed for at least 1 year (as separate overlapping prescriptions or as fixed dose combinations) from 1 year prior to the first FEV1 recording to the last FEV1 recording

 

  • Ordered from lowest to highest as long-acting bronchodilator only, ICS monotherapy, ICS+LABD, LAMA+LABA and triple therapy (ICS+LAMA+ LABA), and then grouped into ICS or non-ICS

Annual exacerbation rate

  • Exacerbations occurring after initiation of the highest level of maintenance therapy until the last FEV1 recording were counted and divided by the total time of follow-up (days/365)

 

  • COPD exacerbation was defined as occurrence of any of the following events: respiratory-related hospital attendance/admission; respiratory-related emergency room attendance; prescription of acute OCS course; and/or antibiotics prescribed with evidence of lower respiratory consultation on the same day

 

  • Events occurring within 14 days of each other were considered the same exacerbation

Blood eosinophil count
(<50, 50–349,≥350 cells/µL)

  • Recorded within a maximum 2 year period before or after date of therapy initiation

 

  • Counts measured within 14 days following an OCS prescription were excluded

 

  • Cut-off values 250 and 450 cells/µL also considered

Overall adherence to maintenance therapy
(<50%, 50%–79%, 80%–100%, >100%)

  • Calculated as the ratio of total time covered by prescriptions of maintenance inhalers (all types, not only highest level) and the total duration of follow-up from maintenance therapy initiation to the last FEV1 recording

 

  • Time covered by one inhaler assumed to be 30 days for all inhalers, except for ICS single inhalers for which 50 days was assumed

  • ICS, inhaled corticosteroid; LABA, long-acting beta-agonists; LABD, long-acting bronchodilator; LAMA, long-acting muscarinic antagonist; OCS, oral corticosteroids.