Table 3

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

	Patients (N)	Exacerbations in risk period	Exacerbations in control period	IRR	95% CI
3-month risk period	3523	362	2980	0.79	0.71 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	625	55	534	0.64	0.48 to 0.85
Asthma	2898	307	2446	0.82	0.73 to 0.93
Gender						0.48
Male	1568	155	1338	0.75	0.63 to 0.89
Female	1955	207	1642	0.82	0.71 to 0.95
Medication class switched						0.20
ICS	1801	200	1522	0.87	0.75 to 1.00
LABA	195	18	170	0.73	0.45 to 1.20
LABA-ICS	1024	97	860	0.72	0.58 to 0.89
LAMA	503	47	428	0.70	0.52 to 0.95
Switch: generic/ branded						0.35
Generic to brand	274	247	2071	0.78	0.68 to 0.89
Generic to generic	2433	23	236	0.61	0.39 to 0.94
Brand to brand	816	92	673	0.87	0.70 to 1.09
Switch between MDI and DPI						0.11
Yes	918	76	786	0.64	0.50 to 0.81
No	1617	175	1354	0.83	0.71 to 0.97
Inhaler check in prior year						0.89
Yes	1397	34	276	0.80	0.56 to 1.13
No	2126	328	2704	0.79	0.70 to 0.88

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.