The authors have declared that no competing interests exist.
Conceived and designed the experiments: DAH. Performed the experiments: DAH THC. Analyzed the data: HLN RJG. Wrote the paper: DAH. Designed the mock tables: DAH. Supported in data analysis, results, and discussion: HLN RJG JJA.
Cardiovascular disease (CVD) is one of the leading causes of morbidity and mortality in Vietnam and hypertension (HTN) is an important and prevalent risk factor for CVD in the adult Vietnamese population. Despite an increasing prevalence of HTN in this country, information about the awareness, treatment, and control of HTN is limited. The objectives of this study were to describe the prevalence, awareness, treatment, and control of HTN, and factors associated with these endpoints, in residents of a mountainous province in Vietnam.
Data from 2,368 adults (age≥25 years) participating in a population-based survey conducted in 2011 in Thai Nguyen province were analyzed. All eligible participants completed a structured questionnaire and were examined by community health workers using a standardized protocol.
The overall prevalence of HTN in this population was 23%. Older age, male sex, and being overweight were associated with a higher odds of having HTN, while higher educational level was associated with a lower odds of having HTN. Among those with HTN, only 34% were aware of their condition, 43% of those who were aware they had HTN received treatment and, of these, 39% had their HTN controlled.
Nearly one in four adults in Thai Nguyen is hypertensive, but far fewer are aware of this condition and even fewer have their blood pressure adequately controlled. Public health strategies increasing awareness of HTN in the community, as well as improvements in the treatment and control of HTN, remain needed to reduce the prevalence of HTN and related morbidity and mortality.
Vietnam is in an epidemiological transition. The overall morbidity and mortality from non-communicable diseases (NCDs) in this country has been rising rapidly over the last two decades and the NCDs have become a major societal problem. Data from the national Ministry of Health (MOH) in 2010 showed that morbidity from NCDs was approximately 3 fold higher than that of infectious diseases
Despite its magnitude, hypertension is one of the most preventable risk factors for CVD; it can be easily detected and it can be effectively treated with low-cost drugs. Unfortunately, hypertension awareness, treatment, and control are unacceptably low in many countries, particularly in developing countries
The objectives of the present observational study were to describe the prevalence, awareness, treatment, and control of hypertension, and to examine factors associated with these endpoints, among the adult population residing in Thai Nguyen province, a northern mountainous region of Vietnam.
The present study used data collected in a population-based survey that was carried out among residents of Thai Nguyen, a province in the northern mountainous region of Viet Nam, in mid-2011 (population = 1,131,000, census 2009). A multistage stratified cluster sampling technique was utilized to ensure the representation of ethnic minorities living in remote areas and the poor. In the first stage of sampling, 60 communes were randomly selected from 180 communes throughout Thai Nguyen, using the probability proportionate to size selection procedure. The second stage consisted of selecting 2 villages randomly from each of the sampled communes. The third stage chose a random sample of 24 adult respondents (age≥18 years) from a list of adults living in the sampled village. This sampling strategy generated a sample size of 2,880 potential respondents. Since the prevalence of hypertension in adults less than 25 years old is low in Vietnam, we restricted the present analysis to adults 25 years and older.
All eligible participants completed a structured questionnaire and dietary assessment. Information was collected about participants' age, sex, ethnicity (Kinh vs. minority groups), marital status, location of residence, education level, occupation, income (quintile groups were defined based on monthly income: (1)1–25 US$, (2)26–50, (3)52–75, (4)78–130, and (5)131–1,500), insurance status (yes vs. no), type of insurance (public vs. private), medical history, smoking, and eating habits. Community health workers performed a physical examination on all participants, which included the standardized measurement of weight, height, and blood pressure (BP). All local staff were trained in the standardized measurement of BP. Two consecutive readings of BP were taken on both arms with the participant in a seated relaxed position. The Omron HEM-790IT Automatic Blood Pressure Monitor with Advanced Omron Health Management Software was used to measure BP. The average of the two BP measures was used for purposes of analysis. Local health workers were carefully trained regarding the measurement of BP and the in-person interview survey using a structured questionnaire.
Hypertension was defined according to the Vietnamese Guidelines on Prevention and Control of Hypertension and the Sixth Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High BP guidelines. Hypertension (HTN) was considered to be present: (1) if the systolic BP was ≥140 mmHg or diastolic BP was ≥90 mmHg for participants without diabetes and chronic kidney disease; (2) if the systolic BP was ≥130 mmHg or diastolic BP was ≥80 mmHg for participants with one of these two conditions; (3) if the participant reported a history of HTN; or (4) the participant reported taking anti-hypertensive medications (e.g., a diuretic, calcium channel blockers, beta-blockers, angiotensin-converting-enzyme inhibitors, or angiotensin II receptor blockers) during the prior 2 weeks Awareness of HTN was defined as participant's self-report of any previous diagnosis of HTN by a healthcare professional. The treatment of HTN was defined as self-reported use of a prescription medication (e.g., diuretics, angiotensin converting enzyme inhibitors) for the management of HTN during the previous 2 weeks. Control of HTN was defined as pharmacological treatment of HTN with a BP<140/90 mmHg for those without diabetes and chronic kidney disease, or a BP<130/80 mmHg for those with either one of these two conditions.
Participants who were aged <25 years at the time of the in-person interview, or who did not complete the questionnaire survey, were excluded from the present analysis. The primary outcomes of interest were the prevalence of HTN, awareness, treatment, and control of HTN.
We described our study population in terms of its socio-demographic, clinical, and lifestyle characteristics using simple descriptive statistics. Data were presented as percentages for categorical variables and median (inter quartile range- IQR) for continuous variables. The distribution of BP levels (median and IQR) in the study sample was examined according to select participant's characteristics, and compared using Wilcoxon-sum rank or Kruskal-Wallis tests.
The overall means (95% CIs) of systolic and diastolic blood pressure were calculated using survey (svy) procedures in STATA taking into account the multistage stratified cluster sampling technique that we used in the present study. The prevalence (95% CI) of HTN was described for the total study population and according to participant's socio-demographic, and behavioral characteristics using svy procedures. Logistic regression models (svy procedures) were utilized to examine factors associated with being hypertensive, and awareness of the condition. These factors were chosen based on the results of prior studies including age (25–39 years, 40–59, ≥60 years), sex, ethnicity (King vs. ethnic minority), educational level (primary, junior secondary, senior secondary and vocational/university), occupation (not working, agriculture work, and non-agriculture work), income (quintiles), location (urban vs. rural), BMI (normal, underweight, and overweight), smoking (ever vs. no), and must have salt when eating (yes vs. no), which have shown to be associated with our principal study outcomes. All analyses were performed using STATA 11.0 with (StataCorp. TX).
The study protocol was approved by the Population Council, New York, the Ethics Committee of the Institute of Population, Health, and Development (PHAD), Hanoi, and Thai Nguyen Department of Health, Vietnam. Written informed consent was obtained from all participants.
The study sample consisted of 2,348 adult men and women residing in Thai Nguyen province, Vietnam, who were, on average, 45 years old. In this sample, 42% were men and 63% were of Kinh ethnicity. Overall, the majority of the study population was less than 60 years old, worked in the agricultural sector, lived in a rural area, had a normal body mass index (BMI), never smoked, and preferred having salt with meals (
n | % | |
Age (yrs) | ||
25–39 | 909 | 38.8 |
40–59 | 1,082 | 46.0 |
≥60 | 355 | 15.2 |
Sex | ||
Female | 1,321 | 56.5 |
Male | 1,018 | 43.5 |
Ethnicity | ||
Kinh | 1,475 | 62.7 |
Ethnic minority | 876 | 37.3 |
Education | ||
Primary | 474 | 20.3 |
Junior Secondary | 1,244 | 53.3 |
Senior Secondary | 383 | 16.4 |
Vocational/university | 231 | 10.0 |
Occupation | ||
Not working | 399 | 17.0 |
Agricultural work | 1,527 | 65.0 |
Non-agricultural work | 425 | 18.0 |
Quintile of income | ||
1 | 464 | 22.0 |
2 | 537 | 25.6 |
3 | 278 | 13.2 |
4 | 403 | 19.1 |
5 | 423 | 20.1 |
Location | ||
Urban | 403 | 17.2 |
Rural | 1,943 | 82.8 |
Body mass index (BMI) |
||
Normal (18.5-<25) | 1,714 | 74.0 |
Underweight (<18.5) | 469 | 20.3 |
Overweight (≥25) | 131 | 5.7 |
Ever smoked cigarettes | ||
No | 1,603 | 68.3 |
Yes | 746 | 31.7 |
Must have salt when eating | ||
No | 581 | 24.8 |
Yes | 1,763 | 75.2 |
BMI was calculated as weight(kg)/height(m)2.
Proportions were calculated using svy procedures.
The overall mean of SBP was 125 mmHg (95% CI: 124–126 mmHg) and DBP was 75 mmHg (95% CI: 74–76 mmHg). In examining the distribution of SBP and DBP in our study sample, the median SBP was 123 mmHg (Inter-quartile range: 112–134 mmHg) and DBP was 75 mmHg (68–82 mmHg) (
Shown was distribution of systolic and diastolic of blood pressure according to selected participant's characteristics including age (
The overall prevalence of HTN in this population was 23.3% (95%CI: 21.1%–25.8%). The prevalence of HTN was higher in older individuals, men, Kinh, individuals with lower education, those who were not working, persons with higher income, those living in urban areas, and in those who had ever smoked or were overweight compared with respective comparison groups (
HTN (n = 535) | Awareness of HTN (n = 173) | Treatment among persons who knew they had HTN (n = 72) | Control among persons received treatment (n = 27) | |
Age group (yrs) | ||||
25–39 | 7% (5–11) | 19% (8–39) | 23% (5–61) | 0% (0–0) |
40–59 | 26% (22–30) | 27% (21–35) | 42% (30–56) | 53% (33–72) |
≥60 | 53% (47–58) | 47% (38–56) | 46% (31–62) | 32% (17–51) |
Sex | ||||
Female | 19% (16–22) | 34% (25–43) | 46% (28–66) | 26% (12–47) |
Male | 30% (26–34) | 34% (26–42) | 41% (29–54) | 51% (31–71) |
Ethnic | ||||
Kinh | 24% (21–27) | 33% (27–40) | 48% (35–61) | 38% (25–54) |
Ethnic minority | 22% (18–26) | 38% (28–49) | 28% (15–46) | 42% (24–62) |
Education | ||||
Primary | 36% (29–44) | 30% (22–40) | 49% (28–70) | 59% (28–84) |
Junior Secondary | 18% (16–21) | 36% (27–45) | 42% (26–60) | 36% (16–62) |
Senior Secondary | 25% (19–31) | 35% (22–50) | 31% (14–55) | 40% (11–78) |
Vocational/university | 22% (16–31) | 33% (20–50) | 53% (37–68) | 21% (6–53) |
Occupation | ||||
Not working | 44% (38–50) | 51% (41–61) | 44% (31–59) | 35% (20–54) |
Agricultural work | 18% (15–21) | 24% (18–32) | 40% (25–57) | 31% (14–54) |
Non-agricultural work | 18% (14–24) | 20% (13–31) | 46% (20–74) | 73% (32–94) |
Quintile of income | ||||
1 | 18% (14–23) | 23% (12–39) | 39% (21–61) | 49% (14–85) |
2 | 21% (16–27) | 31% (19–46) | 55% (31–76) | 56% (26–83) |
3 | 20% (15–28) | 38% (20–60) | 15% (4–42) | 27% (5–73) |
4 | 22% (16–29) | 42% (31–53) | 52% (32–71) | 25% (9–55) |
5 | 22% (18–27) | 26% (15–41) | 36% (15–65) | 16% (3–56) |
Location | ||||
Urban | 26%(22–31) | 38%(28–50) | 42%(27–63) | 44%(23–64) |
Rural | 22%(19–25) | 32%(25–38) | 43%(30–56) | 37%(24–52) |
Body mass index (BMI) |
||||
Normal (18.5-<25) | 22%(20–25) | 33%(26–41) | 44%(34–55) | 36%(22–54) |
Underweight (<18.5) | 21%(17–25) | 29%(19–41) | 44%(22–69) | 71%(34–92) |
Overweight (>25) | 46%(34–58) | 45%(29–63) | 41%(18–69) | 20%(5–54) |
Ever smoked | ||||
No | 20%(17–22) | 31%(24–40) | 52%(36–64) | 32%(18–51) |
Yes | 32%(28–36) | 37%(28–47) | 33%(54–78) | 50%(29–71) |
Must have salt when eating | ||||
No | 23%(19–28) | 47%(33–61) | 27%(12–50) | 22%(6–57) |
Yes | 23%(21–26) | 30%(28–47) | 50%(40–61) | 43%(29–57) |
BMI was calculated as weight(kg)/height(m)2.
Proportions (95%CIs) were calculated using svy procedures.
Among those with HTN, only 33.8% (95%CI: 28.1%–40.0%) were aware that they had elevated BP. Among participants diagnosed with HTN, older persons, minorities, and persons with higher education, those who were not working, who had a higher income, were living in urban areas, had a higher BMI, or those who had ever smoked were more likely to be aware of their HTN than respective comparison groups (
Only 43.2% (95%CI: 32.6%–54.5%) of participants who were aware of their HTN received treatment for this condition as measured by taking any anti-hypertensive medication during the last 2 weeks before the survey. Among participants who knew they had HTN, the prevalence of treatment was higher in older persons, women, and Kinh ethnicity compared with younger persons, men, and minorities (
Among participants who were treated with anti-hypertensive medications, only 38.8% (95%CI: 26.8%–52.3%) had their BP controlled. Among participants receiving HTN treatment during the last 2 weeks, persons between 40–59 years old, men, persons with lower educational attainment (primary), those working in the non- agricultural sector, at the 2nd quintile income, who were living in urban areas, and those who were classified as being underweight, who smoked cigarettes, and reported “must have salt when eating” were more likely to have their BP controlled compared with respective comparison groups (
Results from our multivariable regression analysis showed that older individuals (≥40 years), men, and being overweight were significantly associated with a greater likelihood of being diagnosed with HTN. On the other hand, higher educational level (≥junior secondary school) and being underweight were associated with a lower risk of HTN (
Hypertension (n = 535) | Awareness (n = 173) | |||
Adjusted |
p-values | Adjusted |
p-values | |
Age group (yrs) | ||||
25–39 | 1.00 | 1.00 | ||
40–59 | 1.59(0.33–7.74) | 0.56 | ||
≥60 | 4.62(0.77–27.87) | 0.09 | ||
Sex | ||||
Female | 1.00 | 1.00 | ||
Male | 0.37(0.12–1.13) | 0.81 | ||
Ethnic | ||||
Kinh | 1.00 | 1.00 | ||
Ethnic minority | 1.17(0.82–1.68) | 0.37 | 1.62(0.92–2.90) | 0.10 |
Education | ||||
Primary | 1.00 | 1.00 | ||
Junior Secondary | 1.80(0.83–3.86) | 0.13 | ||
Senior Secondary | 3.03(0.85–10.78) | 0.09 | ||
Vocational/university | 1.62(0.58–4.56) | 0.36 | ||
Occupation | ||||
Not working | 1.00 | 1.00 | ||
Agricultural work | 0.62(0.27–1.43) | 0.26 | ||
Non-agricultural work | 0.89(0.56–1.42) | 0.62 | ||
Quintile of income | ||||
1 | 1.0 | 1.0 | ||
2 | 1.57(0.85–2.91) | 0.14 | 2.27(0.85–6.18) | 0.11 |
3 | 1.32(0.69–2.54) | 0.40 | 1.28(0.33–4.94) | 0.71 |
4 | 1.49(0.67–3.34) | 0.32 | 1.38(0.33–5.55) | 0.65 |
5 | 1.29(0.73–2.29) | 0.37 | 0.63(0.15–2.73) | 0.52 |
Location | ||||
Urban | 1.0 | 1.0 | ||
Rural | 1.32(0.82–2.10) | 0.24 | 1.36(0.63–2.93) | 0.44 |
Body mass index (BMI) |
||||
Normal (18.5-<25) | 1.00 | 1.00 | ||
Underweight (<18.5) | 0.80(0.33–1.95) | 0.62 | ||
Overweight (>25) | ||||
Ever smoked cigarettes | ||||
No | 1.00 | 1.00 | ||
Yes | 1.25(0.78–2.00) | 0.35 | ||
Must have salt when eating | ||||
No | 1.00 | 1.00 | ||
Yes | 1.16(0.76–1.77) | 0.49 | 0.55(0.24–1.26) | 0.15 |
BMI was calculated as weight(kg)/height(m)2.
Multivariable logistic regression models with svy procedures in STATA.
The results of our study suggest that nearly one in every four adults in Thai Nguyen are hypertensive. The prevalence of HTN in residents of this province was slightly lower than that of the whole country of Vietnam in a national survey carried out in 8 Vietnamese provinces and cities, but slightly higher than the prevalence of HTN observed among those from the highland region in the same study
The findings of our study indicate that hypertension awareness and management was far from optimal, a disturbing trend that has been observed in many other developing countries
Our study demonstrated that the prevalence of HTN was higher in older persons, men, individuals with lower education (primary), with higher income, living in urban areas or town, those who were overweight, and who had ever smoked; these findings are consistent with the results from previous studies
Our findings also indicated that overweight persons are more likely to be aware that they are hypertensive compared with those having normal body weight; these findings are consistent with the results from other recent studies conducted in both developing and developed countries
Our findings contribute to the ongoing policy debate with respect to the prevention and control of HTN in Vietnam, especially for the current National Targeted Program for Prevention and Control of Cardiovascular disease. Results from the present study, similar to what has been found in a recent national study
In order to better control HTN in Thai Nguyen and throughout the country, primary interventions including early detection and prompt treatment of HTN should be the central focus. Since all drugs used for treating hypertension and hyperlipidemia are now off-patent and available widely across the country, these programs should be relatively easily scaled up through primary health care or outpatient-clinics. Moreover, education programs including mass media approaches to reduce sodium intake, which has been highly recommended by the WHO
The strengths of the present study includes the population-based multistage stratified cluster sampling design which enhances the generalizabilty of the present findings as well as the careful measurement of BP and its possible predisposing factors. However, the study has several limitations that must be kept in mind in interpreting the study results. First, although study staff were well trained in the measurement of BP, we may have overestimated the prevalence, and underestimated the control of elevated BP, since BP levels presented were based on the average of two measurements performed by a local health worker at a single clinic visit
In conclusion, the results of this population-based study indicate that HTN is an important public health problem in Thai Nguyen. Comprehensive intervention strategies that target the general population, and focus on raising the awareness and treatment of the condition and its risk factors, must be put in place in Thai Nguyen to reduce the burden of HTN related disease. Regular surveys in different provinces throughout Vietnam are needed to continually monitor trends in HTN prevalence and factors associated with HTN awareness and management to better inform future interventions aimed at reducing the magnitude and improving treatment and control of this serious condition.
We thank Thai Nguyen Medical School and Thai Nguyen Department of Health for providing support and collaborating in data collection. We would like to express our gratitude to Peter Miller, Director of Population Council Vietnam and a team at Population Council Vietnam for their collaborative work in development of study instruments.