Table 1.

Demographics of Control, ‘COPD Risk (undiagnosed)’ and ‘COPD Diagnosed’ groups

	All	Control group	‘COPD Risk (undiagnosed)’ group	‘COPD Diagnosed’ group	Risk vs. Control, p value	Diagnosed vs. Control, p value	Risk vs. Diagnosed, p value
	(n = 19,994)	(n = 16,161)	(n = 3320)	(n = 513)
Gender, n (%)					< 0.001	< 0.001	< 0.001
Female	9994 (50.0)	8628 (53.4)	1135 (34.2)	231 (45.0)
Male	10,000 (50.0)	7533 (46.6)	2185 (65.8)	282 (55.0)
Age in years, n (%)					0.000	< 0.001	< 0.001
18–39	8369 (41.9)	7717 (47.8)	462 (13.9)	190 (37.0)
40–59	7942 (39.7)	6491 (40.2)	1254 (37.8)	197 (38.4)
60+	3683 (18.4)	1953 (12.1)	1604 (48.3)	126 (24.6)
Marital status, n (%)					< 0.001	0.413	< 0.001
Married or living with partner	16,004 (80.0)	12,640 (78.2)	2951 (88.9)	413 (80.5)
Not married	3954 (19.8)	3496 (21.6)	358 (10.8)	100 (19.5)
Decline to answer	36 (0.18)	25 (0.15)	11 (0.33)	0 (0.00)
Education, n (%)					< 0.001	< 0.001	< 0.001
Less than university degree	8312 (41.6)	5849 (36.2)	2200 (66.3)	263 (51.3)
University (4 years) degree or higher	11,635 (58.2)	10,277 (63.6)	1109 (33.4)	249 (48.5)
Decline to answer	47 (0.24)	35 (0.22)	11 (0.33)	1 (0.19)
Household income (after tax/welfare), n (%)					< 0.001	0.880	< 0.001
CNY 7999 or below	13,606 (68.1)	10,718 (66.3)	2544 (76.6)	344 (67.1)
CNY 8000–15,999	4809 (24.1)	4083 (25.3)	598 (18.0)	128 (25.0)
CNY 16,000 or above	1321 (6.61)	1136 (7.03)	149 (4.49)	36 (7.02)
Decline to answer	258 (1.29)	224 (1.39)	29 (0.87)	5 (0.97)
Employment, n (%)					< 0.001	< 0.001	< 0.001
Not employed	5105 (25.5)	3276 (20.3)	1661 (50.0)	168 (32.7)
Currently employed	14,889 (74.5)	12,885 (79.7)	1659 (50.0)	345 (67.3)

Abbreviations: CNY Chinese Yuan (currency of the People’s Republic of China);