Table 4. Risk of an exacerbation by medication stepped down.

	Adjusted HR	95% CI	p-Value
Drug stepped down
None	Reference
ICS: inhaler dose	0.86	0.77–0.93	<0.001
ICS: mean daily	0.80	0.74–0.87	<0.001
LABA	0.99	0.92–1.11	0.871
Other add-on	0.99	0.91–1.09	0.791

Cox proportional hazard regression was used to assess the association between an exacerbation in the year after each stepdown, compared with no stepdown, after adjusting for sex, age, BMI, smoking history, socioeconomic status, atopy, anxiety, depression, gastroesophageal reflux, and in the year prior to exposure: maximum ICS dose, ICS stability, ICS frequency, reliever frequency, LABA use, at least 2 add-on therapies, exacerbations, annual asthma review, inhaler technique check, and asthma management plan. The rate and number of exacerbations (per 10 person years, N) of patients that had an exacerbation by drug stepped down were none (1.23 per 10 person years, N = 9,984), ICS mean daily (0.84 per 10 person years, N = 2,163), ICS inhaler dose (1.13 per 10 person years, N = 720), LABA (1.18 per 10 person years, N = 458), other add-on (2.02 per 10 person years, N = 564). Abbreviations: BMI, body mass index; HR, hazard ratio; ICS, inhaled corticosteroid; LABA, long-acting beta-agonist.