Table 4.

Incident rates for severe exacerbations and purchases of systemic corticosteroids or antibiotics during follow-up stratified by respiratory hospitalizations in history

Stratifying variable: Number of respiratory hospitalizations in historya	Severe exacerbations	Systemic corticosteroids	Systemic antibiotics
0	0.15 (0.15-0.16)	1.05 (1.04-1.05)	1.26 (1.25-1.27)
1-2	0.74 (0.72-0.76)	2.48 (2.45-2.51)	2.03 (2.01-2.06)
3-5	2.29 (2.22-2.37)	4.57 (4.47-4.68)	3.18 (3.09-3.28)
>5	5.56(5.29-5.83)	8.38 (8.05-8.72)	4.53 (4.29-4.78)

^aOne year prior to follow-up. Incidence rates presented by mean value and 95% confidence interval