Hypertension is a leading risk factor of cardiovascular disease (CVD), accounting for approximately half of the cardiovascular morbidity and mortality, which has become a serious public health problem in the world, especially in developing countries and regions due to poor management [
People living in the Andean mountains of South America, the Himalayan mountains of Tibet, and the Ethiopian summits of Africa are the three largest populations with the longest history of high altitude residency [
Numerous studies on hypertension have been carried out in China in the last few decades [
To explore the magnitude, management, and contributors including the prescription pattern of antihypertensive agents of hypertension among Tajik population in Pamirs, our hypertension center launched an investigation in Taxkorgan county located in the eastern Pamirs with an average altitude of 4000 m and with Tajik population as the main ethnic group, Xinjiang, China. Thereby, the results may provide basis for the design and implementation of appropriate interventions for hypertension in Tajik residents living in Pamirs, extending to Tajikistan with the same ethnicity and approximate conditions in terms of geographical and climatic condition and hypertension-related disease burden.
This cross-sectional study was conducted among Tajik residents in Taxkorgan county with an average altitude above 4000 m, China, between August and September 2015. A three-stage (township-village-resident) random sampling method was used to select participants who were aged ≥18 years from the general population. First, seven townships in Taxkorgan county were selected using simple random sampling (SRS). Second, two villages were selected in each townships using SRS. Finally, participants were chosen using SRS according to the population composition. Participants were chosen from the list provided by the local government registers of households. The sample size was based on a prevalence of hypertension of 40% among the population aged ≥18 years from the region with an altitude of at 4000 m [
The eligible criteria for study population were as follows: (a) residents who live permanently in the local; (b) Tajik ethnicity; (c) residents who are willing to cooperate with the investigation (questionnaire interviews and anthropometric measurements). The exclusion criteria were as follows: (a) residents with mental diseases and without clear consciousness; (b) women who are pregnant. The study was approved by the Ethical Review Board of People’s Hospital of Xinjiang Uygur Autonomous Region, China.
All study investigators and staff members were trained to be familiar with both the aims of the study and the specific tools and methods used. A standardized questionnaire was administered by trained staff to obtain information on demographic characteristics, health-related behaviors, and hypertension-related information. Anthropometric variables were measured by trained staff after the completion of the questionnaire.
Demographic characteristics (sex, age, occupation, education attainment status, personal incomes per family member, marital status, etc.), health-related behaviors (cigarette smoking and alcohol consumption), and hypertension-related information (whether it was previously diagnosed by a doctor? whether it has been treated? whether taking antihypertensive drugs within the previous two weeks?) were investigated by our investigators. Antihypertensive agents were recorded if they were taking them.
Blood pressure (BP) was measured with the OMRON HBP-1300 Professional Portable Blood Pressure Monitor (OMRON, Kyoto, Japan) three times on the right arm positioned at the heart level after the participant was sitting at rest for five minutes, with 30 seconds between each measurement with an observer present. The average of the three readings was used for the analysis.
Anthropometric variables were measured using standard equipment and procedures including height, weight, and waist circumference (WC). Height was measured without shoes using a standard right-angle device and a fixed measurement tape (to the nearest 0.1 cm). Body weight without heavy clothing was measured using an OMRON body fat and weight measurement device (V-body HBF-371, OMRON, Kyoto, Japan). WC was measured in the midpoint between the lower rib and upper margin of the iliac crest, measured by a ruler tape with an insertion buckle at one end (to the nearest 0.1 cm) [
Medications were classified as diuretics, beta-blockers, calcium channel blockers (CCBs), angiotensin-converting enzyme inhibitors (ACEIs), angiotensin II receptor blockers (ARBs), and traditional Chinese medicine (TCM). Except for ACEIs and ARBs, each medication was classified into only one category: participants who used ≥2 class drugs as combination therapy.
Continuous variables were presented as mean and standard deviations (SD) and analyzed using the ANOVA test. Categorical variables were expressed as frequency (
A total of 797 Tajik subjects aged 42.30 ± 15.21 years were enrolled with men accounting for 46.3% (response rate 93.8%). Characteristics of the study population are shown in Table
Baseline characteristics of the study population by sex.
Variables | Men ( | Women ( | Total ( | |
---|---|---|---|---|
Age (years) | 42.19 ± 15.21 | 42.40 ± 15.23 | 42.30 ± 15.21 | 0.849 |
18–44 | 224 (60.7) | 254 (59.3) | 478 (60.0) | |
45–59 | 93 (25.2) | 115 (26.9) | 208 (26.1) | 0.867 |
≥60 | 52 (14.1) | 59 (13.8) | 111 (13.9) | |
Stock raisers ( | 325 (88.1) | 383 (89.5) | 708 (88.8) | 0.601 |
Education attainment status ( | ||||
Primary and lower | 215 (58.4) | 336 (78.3) | 551 (69.1) | |
Junior high | 78 (21.2) | 66 (15.4) | 144 (18.1) | <0.001 |
Senior high and higher | 75 (20.4) | 27 (6.3) | 102 (12.8) | |
Family income per member ( | 0.001 | |||
Low | 247 (66.9) | 336 (78.5) | 583 (73.1) | <0.001 |
High | 122 (33.1) | 92 (21.5) | 214 (26.9) | |
Marital status ( | ||||
Single | 48 (13.0) | 28 (6.5) | 76 (9.5) | <0.001 |
Married | 298 (80.8) | 348 (81.3) | 646 (81.1) | |
Widowed/divorced | 23 (6.2) | 52 (12.2) | 75 (9.4) | |
Current cigarette consumption ( | 137 (37.1) | 2 (0.5) | 139 (17.4) | <0.001 |
Current alcohol intake ( | 69 (18.7) | 0 (0) | 69 (8.6) | — |
Body mass index | ||||
<23.9 kg/m2 | 173 (46.9) | 193 (45.1) | 366 (45.9) | 0.619 |
≥24.0 kg/m2 | 196 (53.1) | 235 (54.9) | 431 (54.1) | |
Waist circumference | ||||
Abdominal obesity ( | 135 (36.6) | 200 (46.7) | 335 (42.0) | 0.003 |
Figures
Level of blood pressure by age and sex (a) for systolic blood pressure and (b) for diastolic blood pressure.
The overall prevalence of prehypertension and hypertension was 30.1% (95% CI, 26.8%–33.5%) and 24.2% (95% CI, 21.2%–27.3%), respectively, as shown in Table
Prevalence of prehypertension and hypertension in the study population.
Stratification | PHT ( | HT1 ( | HT2 ( |
---|---|---|---|
Sex | |||
Men | 30.1 (25.6–34.9) | 23.6 (19.5–28.2) | 39.1 (34.5–43.8) |
Women | 30.1 (26.2–34.7) | 24.8 (20.8–29.0) | 40.8 (35.1–46.2) |
| 1.000 | 0.740 | 0.613 |
Age | |||
18–44 | 29.9 (25.6–34.3) | 20.1 (16.7–23.9) | 33.3 (23.9–33.9) |
45–59 | 31.2 (25.3–37.9) | 28.4 (22.6–38.9) | 49.0 (41.2–51.7) |
≥60 | 28.8 (21.1–37.9) | 34.2 (25.9–43.6) | 54.1 (50.1–61.6) |
| 0.894 | 0.002 | <0.001 |
Education attainment status | |||
Primary and lower | 28.7 (24.6–32.7) | 26.5 (22.9–30.3) | 42.1 (37.1–47.0) |
Junior high | 35.4 (28.0–43.6) | 22.9 (16.7–30.5) | 39.9 (34.3–45.2) |
Senior high and higher | 30.4 (22.2–40.0) | 13.7 (8.2–21.9) | 28.8 (23.1–34.3) |
| 0.297 | 0.006 | 0.017 |
Family income per member | |||
Low (reference) | 30.5 (25.6–35.3) | 23.8 (18.0–29.5) | 41.1 (35.4–46.2) |
High | 28.9 (24.8–33.1) | 25.2 (18.2–32.3) | 39.2 (34.7–45.9) |
| 0.764 | 0.602 | 0.926 |
Marital status | |||
Single (reference) | 36.8 (26.7–48.3) | 15.8 (9.1–25.8) | 31.2 (25.6–36.8) |
Married | 28.9 (25.1–32.8) | 23.5 (20.3–26.9) | 38.5 (33.5–43.7) |
Divorced | 33.3 (23.6–44.8) | 38.7 (28.3–50.2) | 63.2 (56.2–70.1) |
| 0.291 | 0.003 | <0.001 |
Body mass index | |||
<23.9 kg/m2 (reference) | 19.4 (15.3–23.5) | 13.7 (10.1–17.2) | 22.1 (17.8–26.4) |
≥24.0 kg/m2 | 39.2 (34.6–43.8) | 33.2 (28.7–37.6) | 55.7 (50.9–60.4) |
| <0.001 | <0.001 | <0.001 |
Overall | 30.1 (26.8–33.5) | 24.2 (21.2–27.3) | 40.3 (36.1–44.1) |
PHT, prehypertension; HT, hypertension; CI, confidence intervals.1 Based on the criteria of 2010 Chinese High Blood Pressure Guideline.2 Based on the criteria of 2017 ACC/AHA High Blood Pressure Guideline.
Among those with hypertension, 52.8% (95% CI, 45.7%–59.9%) were aware of their condition, 40.9% (95% CI, 33.9%–47.9%) were taking antihypertensive agents, whereas only 9.3% (95% CI, 5.2%–13.6%) achieved BP control, and control rate among treated hypertensives was 22.7% (95% CI, 15.1%–30.3%) in Table
Awareness, treatment, and control of hypertension in the study population.
Awareness ( | Treatment ( | Control ( | Control in the treated ( | |
---|---|---|---|---|
Sex | ||||
Men | 50.6 (39.8–61.2) | 41.3 (30.8–51.9) | 9.2 (3.0–15.4) | 22.3 (13.7–31.0) |
Women | 54.7 (45.1–64.3) | 40.5 (31.1–50.1) | 9.4 (3.8–15.1) | 23.2 (9.5–37.2) |
| 0.664 | 0.909 | 0.995 | 0.913 |
Age | ||||
18–44 | 35.4 (25.7–45.2) | 29.2 (19.9–38.4) | 6.2 (1.3–11.1) | 21.2 (9.5–32.8) |
45–59 | 64.4 (51.8–76.9) | 54.2 (41.1–67.3) | 10.2 (2.2–18.1) | 18.8 (5.2–32.4) |
≥60 | 78.9 (65.4–92.5) | 50.0 (33.3–66.7) | 15.8 (3.6–27.9) | 31.6 (22.6–40.5) |
| <0.001 | 0.004 | 0.223 | 0.560 |
Education attainment status | ||||
Primary and lower | 56.4 (48.7–64.1) | 41.7 (33.9–49.8) | 10.7 (5.8–15.6) | 25.6 (14.3–36.8) |
Junior high | 39.4 (21.7–56.1) | 33.3 (16.2–50.6) | 5.9 (2.5–9.3) | 17.7 (8.4–27.1) |
Senior high and higher | 50.0 (20.0–79.9) | 50.0 (38.2–61.7) | 6.2 (1.5–10.9) | 12.4 (2.9–21.8) |
| 0.214 | 0.520 | 0.314 | 0.271 |
Family income per member | ||||
Low | 51.8 (41.9–60.8) | 36.9 (27.8–46.1) | 6.6 (1.3–11.9) | 17.9 (7.6–28.1) |
High | 56.5 (40.4–70.6) | 44.3 (29.3–59.5) | 11.1 (1.5–20.5) | 25.1(13.2–37.1) |
| 0.724 | 0.469 | 0.778 | 0.879 |
Marital status | ||||
Single | 25.0 (3.7–46.3) | 21.0 (3.4–38.7) | — | — |
Married | 51.9 (43.6–59.3) | 42.1 (34.1–50.0) | 9.2 (2.6–15.5) | 21.8 (11.9–31.6) |
Divorced | 68.9 (51.0–86.8) | 41.3 (22.3–60.4) | 10.0 (2.9–17.1) | 24.2 (4.2–44.1) |
| 0.033 | 0.509 | 0.516 | 0.627 |
Body mass index | ||||
<23.9 kg/m2 | 48.0 (33.6–62.3) | 32.0 (18.6–45.4) | 12.0 (2.6–21.3) | 37.5 (24.5–50.6) |
≥24.0 kg/m2 | 54.5 (46.3–62.8) | 44.1 (35.8–52.3) | 8.4 (3.7–12.9) | 19.0 (4.4–33.6) |
| 0.511 | 0.181 | 0.572 | 0.179 |
Overall | 52.8 (45.7–59.9) | 40.9 (33.9–47.9) | 9.3 (5.2–13.6) | 22.7 (15.1–30.3) |
Control is defined as BP <140/90 mmHg; CI, confidence intervals.
The awareness and treatment of hypertension significantly increased with age (both
Tables
Factors associated with prehypertension from study population by multiple logistic regression.
Stratification | PHT OR (95% CI) | ||
---|---|---|---|
Sex | |||
Men | 111/369 (30.1) | 1 (reference) | 0.458 |
Women | 129/428 (30.1) | 1.19 (0.76–1.87) | |
Age | |||
18–44 | 143/478 (29.9) | 1 (reference) | |
45–59 | 65/208 (31.2) | 0.92 (0.60–1.40) | 0.687 |
≥60 | 32/111 (28.8) | 0.65 (0.35–1.19) | 0.160 |
Education attainment status | |||
Primary and lower | 158/551 (28.7) | 1 (reference) | |
Junior high | 51/144 (35.4) | 1.49 (0.91–2.45) | 0.113 |
Senior high and higher | 31/102 (30.4) | 1.19 (0.68–2.09) | 0.532 |
Family income per member | |||
Low | 178/583 (30.5) | 1 (reference) | 0.540 |
High | 62/214 (28.9) | 0.88 (0.58–1.34) | |
Marital status | |||
Single | 28/76 (36.8) | 1 (reference) | |
Married | 187/646 (28.9) | 1.05 (0.52–2.10) | 0.897 |
Divorced | 25/75 (33.3) | 1.14 (0.43–3.01) | 0.798 |
Body mass index | |||
BMI: <23.9 kg/m2 | 71/366 (19.4) | 1 (reference) | <0.001 |
BMI: ≥24.0 kg/m2 | 169/431 (39.2) | 2.41 (1.44–4.04) | |
Waistline circumference | |||
Normal | 111/462 (24.0) | 1 (reference) | 0.319 |
Abdominal obesity | 129/335 (38.5) | 1.29 (0.78–2.12) | |
Current cigarette consumption | |||
No | 198/658 (30.1) | 1 (reference) | 0.420 |
Yes | 42/139 (30.2) | 1.25 (0.73–2.13) | |
Current alcohol intake | |||
No | 215/728 (29.5) | 1 (reference) | 0.156 |
Yes | 25/69 (36.2) | 1.56 (0.84–2.90) |
Adjusted factors include all above variables. PHT, prehypertension; OR: odd ratio; CI: confidence interval.
Factors associated with hypertension from study population by multiple logistic regression.
Stratification | HT OR (95% CI) | ||
---|---|---|---|
Sex | |||
Men | 87/369 (23.6) | 1 (reference) | 0.281 |
Women | 106/428 (24.8) | 0.77 (0.48–1.24) | |
Age | |||
18–44 | 96/478 (20.1) | 1 (reference) | |
45–59 | 59/208 (28.4) | 1.53 (0.97–2.40) | 0.067 |
≥60 | 38/111 (34.2) | 2.04 (1.15–3.61) | 0.015 |
Education attainment status | |||
Primary and lower | 146/551 (26.5) | 1 (reference) | |
Junior high | 33/144 (22.9) | 0.87 (0.50–1.52) | 0.633 |
Senior high and higher | 14/102 (13.7) | 0.43 (0.22–0.87) | 0.019 |
Family income per member | |||
Low | 139/583 (23.8) | 1 (reference) | 0.399 |
High | 54/214 (25.2) | 1.21 (0.78–1.88) | |
Marital status | |||
Single | 12/76 (15.8) | 1 (reference) | |
Married | 152/646 (23.5) | 0.91 (0.40–2.12) | 0.834 |
Divorced | 29/75 (38.7) | 1.72 (0.60–4.96) | 0.313 |
Body mass index | |||
BMI: <23.9 kg/m2 | 50/366 (13.7) | 1 (reference) | 0.014 |
BMI: ≥24.0 kg/m2 | 143/431 (33.2) | 2.04 (1.15–3.61) | |
Waistline circumference | |||
Normal | 68/462 (14.7) | 1 (reference) | 0.023 |
Abdominal obesity | 125/335 (37.3) | 1.87 (1.09–3.22) | |
Current cigarette consumption | |||
No | 157/658 (23.8) | 1 (reference) | 0.432 |
Yes | 36/139 (25.9) | 1.27 (0.70–2.31) | |
Current alcohol intake | |||
No | 174/728 (23.9) | 1 (reference) | 0.284 |
Yes | 19/69 (27.5) | 1.52 (0.71–3.24) |
Adjusted factors include all above variables; HT, hypertension; OR: odds ratio; CI: confidence interval; the diagnosis of hypertension is based on the criteria of 2010 Chinese High Blood Pressure Guideline.
A total of 74 hypertensive individuals were reported taking antihypertensive drugs at the time of the survey, whereas 59.5% (
Use of antihypertensive medications in the treated hypertensives.
Type of antihypertensive drug | (%) | |
---|---|---|
ACEI/ARBs | 20 | 45.4 |
CCBs | 14 | 31.8 |
Beta blockers | 5 | 11.3 |
Diuretics | 5 | 11.3 |
TCM | 6 | 13.6 |
Two classes | 6 | 13.6 |
ACEI, angiotensin-converting enzyme inhibitors. ARB, angiotensin receptor blockers. CCB, calcium channel blockers. TCM, traditional Chinese medicine.
This survey is the first in Tajik population living in Pamirs with an altitude of at least 4000 m China to report the hypertension status in relatively representative population aged ≥18 years including nearly 90% stock raisers. The prevalence of hypertension is 24.2%, with poor awareness, treatment, and control rates. A minority of hypertensive individuals is treated, and less than 1 in 10 hypertensives have their BP controlled. In addition, control rate of hypertension among treated individuals is less than one quarter. Less than one-seventh receives two or more drugs at the time of survey.
Some studies on hypertension in high-altitude residents have been carried out in the last few decades [
The current study shows different results compared with studies including the same age groups at other high altitudes. For instance, a recent survey of hypertension and diabetes mellitus conducted in Uttarakhand, India (altitude of 2084 m), found that 54.5% of participants aged ≥60 years have hypertension [
The current study contains some information compared with the national hypertension survey. The prevalence of hypertension in Tajik nomads living in Pamirs with altitude of ≥4000 meter is similar to the national prevalence of China for the population aged ≥18 years (23.2%) [
Therefore, our findings highlight the need for developing a region-targeted hypertension education program to coordinate the efforts of detection, prevention, and treatment of hypertension in plateau regions. In addition, considering the limited availability of antihypertensive drugs and the limited affordability of locals, especially of nomads, exploring and promoting simplified, easy-to-master and cost-effective antihypertensive algorithms might be the good pathway for hypertension control.
BMI and body weight are the best predictors of higher BP in high altitude residents [
The Tajik residents mainly live in the Pamirs and are distributed in Taxkorgan county, Xinjiang, China, and Tajikistan, who still share life style and geographical and climatic environment and burden of CVD including hypertension. Therefore, results of the current study could extend to Tajik population from Tajikistan population living in a similar altitude and nearby areas in terms of prevention of hypertension.
Current analysis is strengthened by relatively representative study subjects from the Tajik ethnic group, which makes the report one of the valuable information for public health sectors and for clinical setting. However, this study contains some limitations. First of all, the cross-sectional nature of the study does not allow to get a cause-and-effect relationship between hypertension and related factors. However, it is also the common way of finding problems and providing clues for prevention. Second, current analysis failed to focus on the data of salt intake, blood lipid, and glucose, which might have brought some bias on analysis of associated factors of prehypertension and hypertension. However, their relationship with hypertension is well-established and still the focus when providing individualized treatment or in population level programs. Third, this study had a relatively small sample size, which may have diminished the statistical power for subgroup analysis. Fourth, we tried to provide information on the drug use pattern here, whereas approximately 40% of hypertensive subjects lacked of data on this aspect, which may have had some information bias. This observation needs further confirmation in studies with well-powered sample size.
Prevalence of hypertension is considerable among Tajik nomads aged ≥18 years living in Pamirs with an altitude of ≥4000 m, China with poor awareness, treatment and control rates. Excess weight loss is a vital strategy for prevention of hypertension. In addition, improving the access of primary care, strengthening the ability construction of medical teams and exploring optimized anti-hypertensive algorithms are crucial to improve the hypertension status in the stock-raising region of Pamirs. Current results could also extend to Tajik population from Tajikistan population living similar altitude and nearby areas.
Materials included in the manuscript, excluding the relevant raw data, will be made freely available to any researchers who wish to use them for noncommercial purposes, while preserving any necessary confidentiality and anonymity.
Ethics approval was obtained from the Ethics Review Committee of People’s Hospital of Xinjiang Uygur Autonomous Region.
The authors declare that they have no conflicts of interest.
LW, NL, and MH contributed equally to this work. NL was involved in the study design. NL, LW, MH, SA, DZ, QL, LZ, JH, JH, LC, XZ, LS, and LS collected the data. LW performed the statistical analysis. LW drafted the manuscript. MH critically revised the manuscript. NL, SA, DZ, QL, LZ, JH, and JH gave important suggestions and did significant changes. All authors reviewed and approved the final version of the paper.
This work was supported by a grant from the Department of Science and Technology of Xinjiang Uygur Autonomous Region of China (2017B03015). The authors thank all the individuals who participated in the present study. The authors thank the Ministry of Science and Technology of the People’s Republic of China and the Department of Science and Technology of Xinjiang Uygur Autonomous Region of China for funding the project. The authors thank nurse Riziwangu Abudu for collecting blood samples from participants in this study.
Supplementary Table 1: mean systolic and diastolic blood pressure by age and sex.