Table 2.

Weighted characteristics of the study population by COPD status-NHANES 1999–2002

Variable	Status	COPD						P value
		Yes			No
		N	%	s.e.	N	%	s.e.
Gender	Male	171	33.68	3.10	2931	50.51	0.61	< 0.01
	Female	284	66.32	3.10	2992	49.49	0.61
Age	20–39 years	122	32.56	2.19	2200	40.66	1.20	< 0.01
	40–59 years	132	35.46	2.94	1844	39.00	0.95
	60–79 years	161	27.16	2.60	1505	17.19	0.67
	> 80 years	40	4.82	0.97	374	3.15	0.24
Race	White	295	81.11	2.63	3051	74.08	1.79	0.01
	Black	59	6.42	1.29	974	8.91	1.01
	Others	101	12.47	2.93	1898	17.01	2.07
Education	< high school	155	26.59	2.31	1849	18.98	1.04	< 0.01
	= high school	118	30.88	2.74	1365	25.60	1.15
	> high school	182	42.53	2.83	2709	55.42	1.74
Poverty income ratio	< 1	94	20.00	3.64	980	12.50	0.85	< 0.01
	1 ≤ PIR ≤ median	201	42.66	3.11	2458	35.29	1.39
	> median	160	37.34	3.78	2485	52.21	1.93
Body mass index	≥ 25	308	65.51	2.45	4072	65.28	0.98	0.94
Smoking	Yes	290	64.98	2.52	2828	49.01	1.43	< 0.01
Alcohol use	Yes	306	71.49	2.58	4068	73.48	2.15	0.42
Diabetes	Yes	50	8.22	1.29	540	6.20	0.41	0.10
High blood pressure	Yes	192	37.11	2.68	1685	24.29	0.90	< 0.01
Physical activity	Yes	226	53.75	4.11	3413	65.52	1.46	< 0.01

N Number; %, weighted percent; s.e. standard error; NHANES National Health and Nutrition Examination Survey

P values were calculated from Rao-Scott Chi-square tests