Prevalence, characteristics, and risk of exacerbation in young patients with chronic obstructive pulmonary disease

Table 2 Risk of moderate to severe exacerbation during a 3-year follow up

	Person-years	No of cases	Incidence rate (per person-year)	HR (95% CI)
	Person-years	No of cases	Incidence rate (per person-year)	Crude	Model^a
COPD status
None	6355.70	44	0.0069	Reference	Reference
Young COPD	280.67	3	0.0107	1.30 (0.40–4.29)	2.01 (0.49–8.17)
COPD and smoking status
Never-smoker, non-COPD	3832.77	33	0.0086	Reference	Reference
Ever-smoker, non-COPD	2522.93	11	0.0044	1.10 (0.55–2.21)	0.71 (0.24–2.10)
Never-smoker, Young COPD	107.07	1	0.0093	0.93 (0.13–6.93)	1.60 (0.18–14.20)
Ever-smoker, Young COPD	173.61	2	0.0115	1.70 (0.40–7.27)	1.94 (0.31–12.07)

ISSN: 1465-993X