Table 2

Age-adjusted incidence rate ratios (IRR) of exacerbations, in the 3-month risk period after a brand-to-generic inhaler switch, compared with stable periods

Exacerbations in risk periodExacerbations in control periodIRR95% CI
3-month risk period171916814830.750.64 to 0.88
Variable association may be modified by Patients
Exacerbations in risk period Exacerbations in control period IRR 95%  CI P value
 COPD332413320.780.57 to 1.09
 Asthma115112711510.740.61 to 0.89
 Male809886930.850.68 to 1.06
 Female910807900.670.53 to 0.84
Medication class switched0.12
 ICS363353140.760.53 to 1.07
 LABA182181600.770.47 to 1.27
 LABA-ICS826677220.610.48 to 0.78
 LAMA348482871.100.80 to 1.48
Switch between MDI and DPI0.61
 Yes3112631210.850.60 to 1.22
 No12393410740.750.62 to 0.90
Inhaler check in prior year0.22
 Yes6065351170.640.47 to 0.85
 No1113948510.810.67 to 0.99
  • COPD, chronic obstructive pulmonary disease;DPI, dry powdered inhaler; ICS, inhaled corticosteroid; LABA, long-acting beta agonist; LAMA, long-acting muscarinic antagonist; MDI, metered-dose inhaler.