Table 2.

The prevalence of asthma by different characteristics among people aged 45 and older

Characteristic	Prevalence (%)	95% CI	P
Race			0.002a
Han	2.07	1.86–2.29
Minorities	3.32	2.50–4.38
Sex			0.231a
Male	2.30	2.00–2.63
Female	2.04	1.78–2.34
Age group			< 0.001b
45–49 years	1.17	0.77–1.77
50–59 years	1.45	1.19–1.78
60–69 years	2.36	2.01–2.77
≥ 70 years	3.45	2.92–4.06
Education			< 0.001b
High-school or above	0.92	0.61–1.39
Middle-school	1.64	1.29–2.07
Primary education	2.40	1.97–2.92
Literate	2.48	2.03–3.03
Illiterate	2.89	2.42–3.46
Residence setting			0.242b
Urban	1.88	1.49–2.37
Urban–rural area	1.87	1.29–2.69
Rural	2.28	2.04–2.55
Geographic region			< 0.001b
Northeast	1.57	1.02–2.42
East	1.87	1.55–2.26
South Central	1.87	1.51–2.32
Southwest	2.50	2.01–3.10
North	2.68	2.12–3.38
Northwest	3.16	2.34–4.27
Smoking status			0.005a
Non-smokers	1.91	1.66–2.19
Smokers	2.52	2.19–2.89
Type of cooking			0.003a
Clean	1.95	1.73–2.20
Unclean	2.65	2.26–3.11

The P value was calculated using Chi-square

CI confidence interval

^aChi-square test

^bMantel–Haenszel chi-square test