Table 4.

Extended Cox proportional hazard analysis of hypertension incidence

Characteristic	aHR (95% CI)	P value
Timing of entering the cohort
1991–1997	Ref.
2000–2009	1.10 (1.01 to 1.21)	0.025
2011–2015	1.19 (1.04 to 1.37)	0.010
Geographic region
Western	Ref.
Central	1.26 (1.16 to 1.37)	<0.001
Northeastern	1.56 (1.41 to 1.72)	<0.001
Eastern	1.48 (1.36 to 1.63)	<0.001
Urban (vs rural)	0.94 (0.88 to 1.01)	0.109
Age*
18–29	Ref.
30–39	1.93 (1.41 to 2.65)	<0.001
40–49	3.99 (2.93 to 5.43)	<0.001
50–59	5.16 (3.74 to 7.12)	<0.001
≥60	9.11 (6.50 to 12.77)	<0.001
Female (vs male)	0.81 (0.74 to 0.88)	<0.001
Body mass index (kg/m2)
<18.5	Ref.
18.5–23.9	1.31 (1.16 to 1.48)	<0.001
24.0–27.9	2.07 (1.81 to 2.36)	<0.001
≥28	2.82 (2.37 to 3.34)	<0.001
Race (Han vs others)	1.11 (1.01 to 1.23)	0.032
Married (vs others)	0.92 (0.83 to 1.02)	0.149
Educational attainment
Primary school and below	Ref.
Middle school	0.91 (0.84 to 0.99)	0.020
High school or equivalent	0.86 (0.77 to 0.95)	0.002
College and above	0.82 (0.68 to 0.98)	0.033
Employed (yes vs no)	0.90 (0.82 to 0.99)	0.036
Smoking
Never or smoking cessation	Ref.
Current smoker, cigarettes <20/day	0.98 (0.89 to 1.07)	0.752
Current smoker, cigarettes ≥20/day	1.05 (0.96 to 1.16)	0.237
Alcohol consumption
Never	Ref.
Not more than once per month	0.89 (0.78 to 1.03)	0.125
1–3 times per month	1.17 (1.04 to 1.32)	0.006
1–2 times per week	1.00 (0.89 to 1.12)	0.963
3–4 times per week	1.05 (0.92 to 1.21)	0.412
On a daily basis	1.18 (1.06 to 1.31)	0.002
Physical activity
Very light	Ref.
Light	0.92 (0.83 to 1.02)	0.154
Moderate	0.99 (0.88 to 1.11)	0.930
Heavy and very heavy	0.91 (0.82 to 1.02)	0.118

*Estimated time effect of age, p<0.001.