Demographic characteristics
A total of 70,380 participants aged 35–75 years were included in the study. Table 1 shows that the mean age of the study population was 54.4 years, and 58.0% were women. Most participants were of Han (89.8%) ethnicity and married (91.2%). A total of 69.2% participants were from rural areas. The prevalence of diabetes was 19.5% and the mean BMI was 25.8 kg/m2.
Table 1. Demographic characteristics of the study population
Characteristics
|
All subjects
|
Men
|
Women
|
Total, n (%)
|
70380 (100.0)
|
29539 (42.0)
|
40841 (58.0)
|
Age (years), Mean±SD
|
54.4±9.4
|
55.0±9.6)
|
54.0±9.2
|
BMI(kg/m2) , Mean±SD
|
25.8±3.6
|
25.7±3.5)
|
25.9±3.6
|
Ethnicity, n (%)
|
|
|
|
Han
|
63172 (89.8)
|
26572 (90.0)
|
36600 (89.6)
|
Mongolian
|
6086 (8.6)
|
2513 (8.5)
|
3573 (8.7)
|
Others
|
1122 (1.6)
|
454 (1.5)
|
668 (1.7)
|
Married, n (%)
|
64203 (91.2)
|
27534 (93.2)
|
36669 (89.8)
|
Rural, n (%)
|
48695 (69.2)
|
20659 (69.9)
|
28036 (68.7)
|
History of diseases, n (%)
|
Stroke
|
2315 (3.3)
|
1124 (3.8)
|
1191 (2.9)
|
MI
|
755 (1.1)
|
387 (1.3)
|
368 (0.9)
|
CVD
|
3436 (4.9)
|
1735 (5.9)
|
1701 (4.2)
|
CHD
|
1218 (1.7)
|
666 (2.3)
|
552 (1.4)
|
Diabetes, n (%)
|
13707 (19.5)
|
6137 (20.8)
|
7570 (18.5)
|
Obesity, n (%)
|
17498 (24.9)
|
7229 (24.5)
|
10269 (25.1)
|
Current smoker, n (%)
|
17624 (25.0)
|
14619 (49.5)
|
3005 (7.4)
|
Drinking, n (%)
|
19089 (27.1)
|
15613 (52.9)
|
3476 (8.5)
|
SD, standard deviation; BMI, body mass index; MI, myocardial infarction; CVD, cardiovascular disease; CHD, coronary heart disease.
BP levels
Table 2 shows mean BP levels according to different sex and age groups. The mean SBP and DBP was 140.5±20.9 mmHg and 84.8±11.6 mmHg, respectively. Overall, men had slightly higher SBP and DBP levels than women. The mean SBP increased gradually with age, but mean DBP decreased in higher age groups. Compared with the no hypertensive participants, the SBP was 38.4 and 31.0 higher of the untreated hypertension participants and the treated hypertension participants, respectively, and the DBP was 18.3 and 13.7 higher, respectively. In contrast, the mean SBP and DBP among treated patients with hypertension was 7.4 mmHg and 4.6 mmHg, respectively, lower than the values among untreated patients with hypertension. The difference in SBP and DBP between treated and untreated patients was statistically significant (P<0.05).
The percentage distribution of BP levels among study participants is shown in the Figure 1. Overall, only 13.9% of the study population (11.7% of men and 15.4% of women) had optimal BP whereas nearly two-fifths (38.6%) had high normal BP. The prevalence of stage 1, 2, and 3 hypertension was 30.6%, 10.7%, and 6.3% in men (29.1%, 12.2%, and 6.1% in women), respectively. With increasing age, the percentage of optimal and high-normal BP decreased whereas the proportion of stage 1, stage 2, and stage 3 hypertension increased.
Table 2. Systolic and diastolic blood pressure among study participants by sex and age
Age
(years)
|
Total
|
|
No hypertension
|
|
Treated
|
|
Untreated
|
SBP
(mmHg)
|
DBP
(mmHg)
|
|
SBP
(mmHg)
|
DBP
(mmHg)
|
|
SBP
(mmHg)
|
DBP
(mmHg)
|
|
SBP
(mmHg)
|
DBP
(mmHg)
|
Men
|
140.7±19.9
|
86.7±11.4
|
|
124.6±9.1
|
78.5±6.8
|
|
152.9±19.7
|
92.3±11.7
|
|
161.2±17.2
|
97.7±11.0
|
35-
|
133.3±17.0
|
85.7±11.6
|
|
123.0±8.8
|
78.7±6.7
|
|
148.9±18.6
|
96.9±11.7
|
|
156.2±14.5
|
101.4±9.7
|
45-
|
138.8±19.2
|
88.1±11.5
|
|
124.3±8.9
|
79.5±6.5
|
|
151.2±19.4
|
95.9±11.4
|
|
160.6±17.2
|
101.0±10.7
|
55-
|
143.1±20.1
|
87.0±11.1
|
|
125.3±9.2
|
78.3±6.6
|
|
153.4±19.8
|
92.1±11.2
|
|
161.9±17.6
|
96.4±10.3
|
65-75
|
146.2±20.6
|
84.4±11.1
|
|
126.2±9.3
|
76.1±7.3
|
|
154.9±20.0
|
87.7±11.2
|
|
164.1±17.5
|
92.3±11.0
|
Women
|
140.4±21.5
|
83.4±11.5
|
|
123.2±9.9
|
76.0±7.4
|
|
155.8±20.5
|
89.6±11.5
|
|
162.8±17.3
|
93.3±10.6
|
35-
|
127.9±17.7
|
80.4±11.5
|
|
119.8±10.0
|
75.5±7.5
|
|
151.9±19.0
|
95.3±11.6
|
|
158.6±15.4
|
97.7±9.7
|
45-
|
137.8±20.4
|
84.0±11.6
|
|
123.2±9.7
|
76.6±7.3
|
|
153.7±20.4
|
92.4±11.3
|
|
162.1±17.0
|
96.2±10.1
|
55-
|
145.1±20.9
|
84.3±11.1
|
|
125.7±9.4
|
76.1±7.2
|
|
155.9±20.4
|
89.0±11.0
|
|
163.3±17.6
|
92.2±10.2
|
65-75
|
151.4±21.3
|
83.2±11.3
|
|
126.9±9.3
|
74.3±7.7
|
|
159.1±20.8
|
86.0±11.5
|
|
164.8±17.6
|
88.6±10.7
|
Total
|
140.5±20.9
|
84.8±11.6
|
|
123.7±9.6
|
77.0±7.3
|
|
154.7±20.3
|
90.7±11.7
|
|
162.1±17.3
|
95.3±11.0
|
35-
|
130.1±17.6
|
82.6±11.8
|
|
121.0±9.7
|
76.6±7.4
|
|
150.5±18.8
|
96.1±11.6
|
|
157.3±14.9
|
99.8±9.9
|
45-
|
138.2±20.0
|
85.6±11.7
|
|
123.6±9.4
|
77.7±7.2
|
|
152.7±20.0
|
93.8±11.5
|
|
161.4±17.1
|
98.4±10.6
|
55-
|
144.3±20.6
|
85.5±11.2
|
|
125.6±9.3
|
77.1±7.1
|
|
154.9±20.2
|
90.2±11.2
|
|
162.7±17.6
|
94.0±10.4
|
65-75
|
148.9±21.1
|
83.8±11.2
|
|
126.5±9.3
|
75.3±7.5
|
|
157.4±20.6
|
86.7±11.4
|
|
164.5±17.6
|
90.3±11.0
|
SBP, systolic blood pressure; DBP, diastolic blood pressure.
Prevalence, awareness, treatment, control, and control under treatment of hypertension
Table 3( see Additional file 1) shows that the crude prevalence of hypertension was 55.7% (55.3%–56.1%), and the age- and sex-standardized rate was 49.4% (49.0%–49.8%). A total 52.8% (52.3%–53.3%) of patients with hypertension were aware of their diagnosis. Among participants with hypertension, 43.3% (42.8%–43.8%) of patients were taking medications to lower BP, and only 8.6% (8.3%–8.9%) had their BP controlled to less than 140/90 mmHg. Additionally, only 19.8% (19.2%-20.4%) of treated participants with hypertension had mean SBP <140 mmHg and DBP <90 mmHg. The age- and sex-standardized rates of hypertension awareness, treatment, control, and control under treatment were 45.4% (44.9%–45.9%), 35.7% (35.2%–36.2%), 7.3% (7.0%–7.6%), and 20.8% ( 20.2%–21.4%), respectively.
There was a higher prevalence of hypertension among participants who were male, of Han ethnicity, older, unmarried, uninsured, living in a rural area, and those who had lower education or income levels. Patients with a history of diseases (stroke, MI, CVD, CHD) and CVD risk factors (diabetes, obesity, drinking) had higher prevalence of hypertension.
The prevalence, awareness, and treatment of hypertension increased with age (trend chi-square tests: P<0.001). In contrast, control under treatment for hypertension decreased with age (trend chi-square tests: P<0.001). The prevalence of hypertension was significantly greater among men than among women (57.4% vs 54.5%, P<0.001). Compared with men (49.7%), women (55.2%) were more aware of their hypertension status and were more likely to take medication (46.1% vs 39.6%) and achieve control under treatment (8.8% vs 8.2%). However, women (19.2%) had lower control rates under treatment for hypertension than men (20.8%) (Table 3, see Additional file 1).
Hypertension was categorized as unaware of disease, aware but not treated, treated but not controlled, or controlled (Figure 2). Most patients with hypertension were unaware of their, aware but untreated, and treated but not controlled. The control rates of hypertension among patients with hypertension were very low among all age groups.