A total of 70,380 participants aged 35–75 years were included in the study. Characteristics of the study population are shown in Table 1. Among participants, 58.0% were female, the mean age was 54.4 (SD: 9.4) years. The mean SBP and DBP was 140.5 (SD:20.9) mmHg and 84.8 (SD:11.6) mmHg, respectively. The prevalence of diabetes was 19.5% and the mean BMI was 25.8 (SD:3.6) kg/m2.
Table 1. Baseline characteristics of the study population
Characteristics
|
All subjects
(N=70,380)
|
Age (years), Mean±SD
|
54.4±9.4
|
Blood pressure(mmHg) , Mean±SD
|
|
SBP
|
140.5±20.9
|
DBP
|
84.8±11.6
|
BMI(kg/m2) , Mean±SD
|
25.8±3.6
|
Normal, n(%)
|
5294(7.5)
|
Overweight, n(%)
|
47588 (67.6)
|
Obesity, n(%)
|
17498 (24.9)
|
Gender, n(%)
|
|
Male
|
29539 (42.0)
|
Female
|
40841 (58.0)
|
Location of residence, n(%)
|
|
Rural
|
48695 (69.2)
|
Urban
|
21685 (30.8)
|
Marital status
|
|
Married
|
64203 (91.2)
|
Not married
|
6177 (8.8)
|
Ethnicity, n (%)
|
|
Han
|
63172 (89.8)
|
Mongolian
|
6086 (8.6)
|
Others
|
1122 (1.6)
|
Annual household income, n(%)
|
|
<10000(yuan)
|
19716 (28.0)
|
10000-50000(yuan)
|
36980 (52.6)
|
>50000(yuan)
|
8044 (11.4)
|
Unknown
|
5640 (8.0)
|
Educational level, n (%)
|
|
Primary school or lower
|
28466 (40.5)
|
Middle school
|
30576 (43.4)
|
High school
|
7814 (11.1)
|
Unknown
|
3524 (5.0)
|
Farmer, n (%)
|
33186 (47.2)
|
Health insurance, n(%)
|
61139 (86.9)
|
Diabetes, n (%)
|
13707 (19.5)
|
Current smoker, n (%)
|
17624 (25.0)
|
Current drinker, n (%)
|
19089 (27.1)
|
Data are shown as n(%) or mean ± SD. Abbreviations: SD, standard deviation; SBP, Systolic blood pressure; DBP, diastolic blood pressure; BMI, body mass index.
The blood pressure levels
Figure 1 shows gender- and age-specific mean blood pressure values for the all participants and for 3 subgroups defined by hypertension status. Overall, the mean SBP increased gradually with age throughout entire age range, whereas the mean DBP decreased in 65-75 age group. Overall, the mean SBP and DBP among participants with hypertension were 30.95 (95% CI: 30.62-31.27) mmHg and 13.63 (13.44-13.83) mmHg lower than the corresponding values among those with treated hypertension, and 38.33 (37.76-38.89) mmHg and 18.27 (17.90-18.63) mmHg lower than the corresponding values for those with untreated hypertension. The overall SBP and DBP differences between treated and untreated participants with hypertension were 7.38 (6.75-8.01) mmHg and 4.64 (4.24-5.03) mmHg, respectively. And the differences were statistically significant (SBP: t’=-20.644, P<0.001; DBP: t’=-22.999, P<0.001).
The percentage distribution of blood pressure levels among study participants is shown in the Figure 2. Overall, only 13.4% of the study population (11.5% of men and 14.7% of women) had optimal blood pressure, whereas nearly two-fifths (38.8%) had high normal blood pressure. The prevalence of stage 1, 2, and 3 hypertension was 30.7%, 10.7%, and 6.3% in male and 29.4%, 12.3%, and 6.2% in female, respectively. With increasing age, the percentage of optimal and high-normal blood pressure decreased whereas the proportion of stage 1, stage 2, and stage 3 hypertension increased (Trend Chi-square tests: male, =999.9, P<0.001; female, =41666.2, P<0.001).
Prevalence, awareness, treatment and control of hypertension risk factors
The prevalence, awareness, treatment, control and control under treatment of hypertension by different groups is showed in Table 2. The crude rates of prevalence awareness, treatment, control and control under treatment for hypertension was 55.7% (95% CI: 55.3%-56.1%), 52.8% (95%CI: 52.3%-53.3%), 43.3% (95%CI: 42.8%-43.8%), 8.6% (95%CI: 8.3%-8.9%) and 19.8% (19.2%-20.4%), respectively. The national standardized prevalence rate and the regional standardized prevalence rate was 49.4% (49.0%-49.8%) and 55.4% (55.0%-55.8%), respectively. The 70,380 population subgroups varied with respect to hypertension prevalence (range: 32.6%-73.4%), awareness (35.1%-76.2%), treatment (24.9%-64.6%), control (3.9%-20.4%), and control under treatment (11.2%-31.6%).
Table 2. Prevalence, awareness, treatment, control, and control under treatment of hypertension among different groups, %(95%CI)a
Groups
|
Prevalence
|
Awareness
|
Treatment
|
Control
|
Control under treatment
|
Crude rates
|
55.7(55.3-56.1)
|
52.8(52.3-53.3)
|
43.3(42.8-43.8)
|
8.6(8.3-8.9)
|
19.8(19.2-20.4)
|
Standardized ratesb
|
55.4(55.0-55.8)
|
51.2(50.7-51.7)
|
43.8(43.3-44.3)
|
8.2(7.9-8.5)
|
19.4(18.8-20.0)
|
Standardized ratesc
|
49.4(49.0-49.8)
|
45.4(44.9-45.9)
|
35.7(35.2-36.2)
|
7.3(7.0-7.6)
|
20.8(20.2-21.4)
|
Gender
|
|
|
|
|
|
Male
|
57.4(56.8-58.0)
|
49.7(48.9-50.4)
|
39.6(38.9-40.3)
|
8.2(7.8-8.6)
|
20.8(19.8-21.7)
|
Female
|
54.5(54.0-54.9)
|
55.2(54.5-55.8)
|
46.1(45.4-46.7)
|
8.8(8.5-9.2)
|
19.2(18.4-20.0)
|
Ethnicity
|
|
|
|
|
|
Han
|
56.0(55.6-56.4)
|
53.6(53.1-54.1)
|
44.2(43.7-44.7)
|
8.9(8.6-9.2)
|
20.2(19.6-20.8)
|
Mongol
|
52.7(51.4-53.9)
|
44.6(42.9-46.4)
|
34.2(32.6-35.9)
|
5.1(4.4-5.9)
|
15.0(12.9-17.2)
|
Others
|
53.2(50.3-56.1)
|
48.9(44.9-52.9)
|
38.9(35.0-42.8)
|
6.0(4.1-7.9)
|
15.5(10.9-20.2)
|
Age (years)
|
|
|
|
|
|
35-44
|
32.6(31.7-33.4)
|
35.1(33.6-36.6)
|
24.9(23.5-26.2)
|
5.3(4.6-6.0)
|
21.4(18.8-24.0)
|
45-54
|
50.6(50.0-51.3)
|
47.9(47.1-48.8)
|
38.1(37.2-38.9)
|
8.0(7.5-8.5)
|
21.0(19.8-22.2)
|
55-64
|
64.2(63.6-64.8)
|
56.9(56.1-57.7)
|
47.8(47.0-48.5)
|
9.5(9.0-9.9)
|
19.8(18.9-20.7)
|
65-75
|
73.4(72.5-74.2)
|
60.9(59.9-62.0)
|
51.6(50.5-52.7)
|
9.3(8.7-9.9)
|
18.0(16.9-19.2)
|
Marital status
|
|
|
|
|
|
Married
|
55.1(54.7-55.5)
|
53.0(52.5-53.5)
|
43.4(42.9-44.0)
|
8.9(8.6-9.2)
|
20.4(19.8-21.0)
|
Not married
|
62.0(60.8-63.2)
|
50.9(49.3-52.5)
|
41.8(40.3-43.4)
|
5.9(5.2-6.7)
|
14.2(12.5-15.9)
|
Farmer
|
|
|
|
|
|
Yes
|
56.7(56.2-57.3)
|
51.8(51.1-52.5)
|
41.4(40.7-42.1)
|
7.6(7.2-8.0)
|
18.4(17.5-19.3)
|
No
|
54.8(54.2-55.3)
|
53.8(53.1-54.4)
|
45.1(44.4-45.7)
|
9.5(9.1-9.9)
|
21.0(20.2-21.8)
|
Location of residence
|
|
|
|
|
Rural
|
56.0(55.6-56.5)
|
52.5(51.9-53.1)
|
42.4(41.8-43.0)
|
8.3(8.0-8.6)
|
19.5(18.8-20.3)
|
Urban
|
54.9(54.3-55.6)
|
53.6(52.7-54.5)
|
45.3(44.4--46.2)
|
9.2(8.7-9.8)
|
20.4(19.3-21.5)
|
Educational level
|
|
|
|
|
|
Primary school or lower
|
58.8(58.3-59.5)
|
54.3(53.6-55.1)
|
44.3(43.6-45.1)
|
8.0(7.6-8.4)
|
18.1(17.2-19.0)
|
Middle school
|
54.4(53.8-54.9)
|
53.2(52.4-53.9)
|
44.0(43.2-44.7)
|
9.5(9.0-9.9)
|
21.5(20.6-22.4)
|
High school
|
47.8(46.7-48.9)
|
49.8(48.2-51.4)
|
40.1(38.5-41.7)
|
9.5(8.5-10.4)
|
23.6(21.5-25.8)
|
Unknown
|
58.8(57.2-60.4)
|
43.3(41.2-45.4)
|
45.9(43.0-48.8)
|
11.2(9.3-13.0)
|
16.8(14.7-18.9)
|
Annual Income (RMB)
|
|
|
|
|
<10000
|
58.6(58.0-59.3)
|
53.7(52.8-54.6)
|
42.8(41.9-43.7)
|
8.2(7.7-8.7)
|
19.1(18.0-20.2)
|
10000-50000
|
54.4(53.9-54.9)
|
52.9(52.2-53.6)
|
44.2(43.5-44.9)
|
9.0(8.6-9.4)
|
20.3(19.5-21.1)
|
>50000
|
54.2(53.1-55.3)
|
53.8(52.3-55.3)
|
43.4(41.9-44.9)
|
9.2(8.4-10.1)
|
21.3(19.4-23.1)
|
Unknown
|
61.9(60.2-63.5)
|
47.6(45.9-49.4)
|
35.0(32.9-37.1)
|
3.9(3.1-4.8)
|
11.2(8.8-13.5)
|
Health insurance
|
|
|
|
|
|
Yes
|
55.5(55.1-55.9)
|
53.4(52.9-53.9)
|
43.8(43.3-44.3)
|
8.8(8.5-9.1)
|
20.0(19.3-20.6)
|
No
|
56.9(55.9-57.9)
|
49.0(47.7-50.4)
|
39.9(38.6-41.3)
|
7.4(6.7-8.1)
|
18.6(17.0-20.3)
|
Diabetes
|
|
|
|
|
|
Yes
|
70.2(69.4-70.9)
|
60.2(59.2-61.2)
|
50.8(49.8-51.8)
|
9.6(9.1-10.2)
|
19.0(17.9-20.1)
|
No
|
52.2(51.8-52.6)
|
50.4(49.8-51.0)
|
40.8(40.3-41.4)
|
8.2(7.9-8.5)
|
20.1(19.4-20.9)
|
Obesity
|
|
|
|
|
|
Yes
|
71.4(70.7-72.0)
|
60.7(59.8-61.5)
|
51.2(50.3-52.1)
|
8.9(8.4-9.4)
|
17.4(16.5-18.4)
|
No
|
50.5(50.1-50.9)
|
49.1(48.5-49.7)
|
39.6(39.0-40.2)
|
8.4(8.1-8.7)
|
21.2(20.5-22.0)
|
Current smoker
|
|
|
|
|
|
Yes
|
53.2(52.5-54.0)
|
50.7(49.7-51.7)
|
40.8(39.8-41.8)
|
9.4(8.8-10.0)
|
23.0(21.7-24.3)
|
No
|
56.6(56.1-56.9)
|
53.5(52.9-54.0)
|
44.1(43.5-44.6)
|
8.3(8.0-8.6)
|
18.9(18.2-19.5)
|
Current Drinker
|
|
|
|
|
|
Yes
|
57.0(56.3-57.7)
|
46.4(45.5-47.4)
|
34.9(34.0-35.8)
|
6.3(5.9-6.8)
|
16.0(14.8-17.1)
|
No
|
55.2(54.8-55.6)
|
55.3(54.7-55.8)
|
46.5(45.9-47.1)
|
9.4(9.1-9.8)
|
20.3(19.6-21.0)
|
Prior CVD
|
|
|
|
|
|
Yes
|
72.7(71.2-74.2)
|
72.0(70.2-73.7)
|
60.2(58.2-62.1)
|
14.5(13.1-15.9)
|
24.1(21.9-26.3)
|
No
|
54.8(54.4-55.2)
|
51.5(51.0-52.0)
|
51.5(51.0-52.0)
|
8.2(7.9-8.5)
|
19.4(18.8-20.0)
|
Prior CHD
|
|
|
|
|
|
Yes
|
68.4(65.8-71.0)
|
76.2(73.3-79.1)
|
64.6(61.3-67.8)
|
20.4(17.7-23.1)
|
31.6(27.7-35.5)
|
No
|
55.5(55.1-55.8)
|
52.3(51.8-52.8)
|
42.8(42.3-43.3)
|
8.3(8.0-8.6)
|
19.4(18.8-20.0)
|
a: The value is presented in percent (95% confidence interval). b: Regional level standardized rates adjusted for age, gender, location of residence, and ethnicity. c: Age- and sex-standardized rates at national level. Abbreviations: CVD, cardiovascular disease; CHD, coronary heart disease.
Hypertension was categorized as unaware of disease, aware but not treated, treated but not controlled, or controlled (Figure 3). In this study populations, hypertension patients accounted for 55.7%, of which 26.3% were unaware of disease, 19.3% were treated but not controlled, 5.3% were aware but not treated, and only 4.8% were controlled. The proportion of the hypertension patients and the proportion of each part increased with age. The control rate among patients with hypertension were very low among all age groups in both male and female.
Using the multivariate logistic model, we identified several significant determinants that were associated with prevalence and control of hypertension (Figure 4). Mongol people had 13.1% lower odds of being suffer from hypertension, and had 36.1% lower odds of being control hypertension compared with those of Han people. Younger patients were less likely to suffer from and control hypertension whereas those aged 35-44 years had the lowest odds ratios of being hypertension and reaching the target for blood pressure. In addition, among populations who had dyslipidemia, diabetes, obesity, not married, current drinker, non-current smoker, were farmer, living in rural areas, were male and old age were significantly more likely to be suffered from hypertension. Patients who were farmer, not married, current drinker, non-current smoker, young age, without obesity and without prior CVD were less likely to be controlled for hypertension.
Distance to treatment targets
The distance to the optimal targets of blood pressure were calculated in uncontrolled patients (Table 3). Uncontrolled hypertension who were treated had a larger distance to the target values of SBP and DBP than those who were untreated both in male and female. And uncontrolled hypertension had a larger distance to the target values of SBP than DBP.
Table 3. The distance to the optimal targets of blood pressure in uncontrolled participantsa
Distance to the target blood pressure values
|
Uncontrolled
|
Treated
|
Untreated
|
Pb
|
Male
|
|
|
|
|
SBP (distance to 140mmHg)
|
11.5(3.5-23.0)
|
16.5(6.5-29.0)
|
9.5(2.0-19.5)
|
<0.001
|
DBP (distance to 90mmHg)
|
3.0(-2.0-9.5)
|
5.0(-5.0-12.0)
|
2.5(-2.5-8.0)
|
<0.001
|
Female
|
|
|
|
|
SBP (distance to 140mmHg)
|
14.0(5.5-26.0)
|
19.0(9.0-32.0)
|
11.0(3.5-21.0)
|
<0.001
|
DBP (distance to 90mmHg)
|
0.5(-6.0-7.0)
|
2.0(-5.0-9.0)
|
0.0(-6.5-5.5)
|
<0.001
|
Total
|
|
|
|
|
SBP (distance to 140mmHg)
|
13.0(4.5-24.5)
|
18.0(8.0-30.5)
|
10.5(3.0-20.5)
|
<0.001
|
DBP (distance to 90mmHg)
|
1.5(-4.5-8.0)
|
3.0(-3.5-10.0)
|
1.0(-5.0-7.0)
|
<0.001
|
a: The values were presented by Median and interquartile range (IQR); b: Wilcoxon rank sum test. Abbreviations: SBP, systolic blood pressure; DBP, diastolic blood pressure; The distance to SBP was calculated by subtracting 140(mmHg) from the SBP of each group of subjects; the distance to DBP was calculated as the measurement of DBP minus 90(mmHg) among the DBP of each group of subjects.