Table 2. Number of subjects and incidence cases for chronic obstructive pulmonary disease (COPD) and incidence rate by sex and smoking status.

Brinkman Index†	Males			Females
	n	Number of incidence cases for COPD	Incidence rate (per 100 person-years)	n	Number of incidence cases for COPD	Incidence rate (per 100 person-years)
Total	11,160	387	0.81	5,946	79	0.31
Non-smokers	2,784	52	0.44	5,416	74	0.32
Former smokers	3,541	111	0.70	201	0	0.00
Current smokers	4,835	224	1.14	329	5	0.44
<400	1,712	29	0.39	284	3	0.28
400-799	2,126	100	1.11	38	2	1.30
800+	997	95	2.64	7	0	0.00

† : number of cigarettes per day × total years smoking.