Table 1

Characteristics of patients according to spirometry-defined COPD grade

	Total sample(N = 8215)	No COPD(N = 7122)	COPD(N = 1093)	COPD grade
	Total sample(N = 8215)	No COPD(N = 7122)	COPD(N = 1093)	Mild(N = 455)	Moderate(N = 480)	Severe or very severe(N = 158)
*p<0.001, p<0.01, *p<0.02.
†Adjusted for age.
‡Excluding non-smokers.
¶Adjusted for age, sex and deprivation level.
§Adjusted for age and sex.
^a,b,cDifferent letters indicate significant group differences (p<0.02).
Demographic data
Mean (SD) age	55.5 (13.5)	54.4 (13.2)	62.5 (13.4)***	60.2 (14.2)^a	63.0 (13.0)^a	67.2 (10.8)^b
% (N) male	46.4 (3808)	44.7 (3185)	57.0 (623)***	50.8 (231)^a	61.9 (297)^b	60.1 (95)^a,b
% (N) manual occupation	44.6 (3664)	43.6 (3105)	51.1 (559)***	44.6 (203)^a	55.6 (267)^b	56.3 (89)^b
Mean (SD) deprivation score†	1.1 (1.2)	1.1 (1.1)	1.3 (1.2)***	1.2 (1.2)^a	1.7 (1.2)^b	1.8 (1.2)^b
Smoking characteristics
% (N) smoking prevalence
Age 36–44	30.4 (654)	29.6 (599)	43.3 (55)**	45.5 (35)^a	40.0 (18)^a	40.0 (2)^a
Age 45–54	28.8 (610)	26.7 (511)	47.8 (99)***	37.5 (39)^a	57.3 (51)^b	64.3 (9)^a,b
Age 55–64	22.0 (379)	19.1 (281)	40.0 (98)***	26.5 (26)^a	47.2 (50)^b	53.7 (22)^b
Age 65+	15.1 (335)	12.0 (205)	25.3 (130)***	19.3 (34)^a	27.1 (65)^a,b	31.6 (31)^b
All ages
Current	24.1 (1978)	22.4 (1596)	34.9 (382)***	29.5 (134)^a	38.3 (184)^b	40.5 (64)^b
Ever	55.1 (4529)	52.8 (3758)	70.5 (771)***	60.4 (275)^a	75.8 (364)^b	83.5 (132)^b
Mean (SD) cigarettes/day‡	15.1 (9.5)	14.8 (9.2)	16.3 (10.4)*	16.3 (9.2)^a	17.1 (11.6)^a	13.9 (8.5)^a
Mean (SD) saliva cotinine (ng/ml)‡	286 (177)	278 (177)	322 (173)***	306 (171)^a	336 (169)^a	318 (192)^a
Mean (SD) dependence rating¶	3.7 (1.0)	3.6 (1.0)	3.9 (1.0)***	3.9 (1.0)^a	3.8 (0.9)^a	3.6 (1.0)^a
% (N) motivated to quit§	68.9 (1200)	68.0 (955)	70.8 (239)	65.2 (76)^a	77.3 (126)^a	61.8 (37)^a

Respiratory diagnosis
% (N) chronic bronchitis/emphysema	1.1 (89)	0.7 (52)	3.4 (37)***	0.4 (2)^a	3.3 (16)^b	12.0 (19)^c
% (N) asthma	5.6 (456)	4.5 (319)	12.5 (137)***	5.1 (23)^a	14.0 (67)^b	29.7 (47)^c
% (N) undefined	2.0 (164)	1.7 (123)	3.8 (41)***	0.9 (4)^a	5.0 (24)^b	8.2 (13)^b
% (N) any	8.2 (671)	6.5 (466)	18.8 (205)***	6.4 (29)^a	21.3 (102)^b	46.8 (74)^c