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

	Patients (N)	Exacerbations in risk period	Exacerbations in control period	IRR	95% CI
3-month risk period	1719	168	1483	0.75	0.64 to 0.88
Variable association may be modified by	Patients (N)	Exacerbations in risk period	Exacerbations in control period	IRR	95% CI	P value
Disease						0.09
COPD	332	41	332	0.78	0.57 to 1.09
Asthma	1151	127	1151	0.74	0.61 to 0.89
Gender						0.22
Male	809	88	693	0.85	0.68 to 1.06
Female	910	80	790	0.67	0.53 to 0.84
Medication class switched						0.12
ICS	363	35	314	0.76	0.53 to 1.07
LABA	182	18	160	0.77	0.47 to 1.27
LABA-ICS	826	67	722	0.61	0.48 to 0.78
LAMA	348	48	287	1.10	0.80 to 1.48
Switch between MDI and DPI						0.61
Yes	311	263	121	0.85	0.60 to 1.22
No	1239	34	1074	0.75	0.62 to 0.90
Inhaler check in prior year						0.22
Yes	606	535	117	0.64	0.47 to 0.85
No	1113	948	51	0.81	0.67 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.