Regional Health Forum

Regional Health Forum WHO South-East Asia Region Volume 8 Number 1, 2004

Noncommunicable Diseases

Prevalence of Hypertension in Two Selected Villages
of Kayin State, Myanmar

By San Shwe*, Ohnmar^*, Kyu Kyu Than^*, Than Tun Sein**, Aung Thu^*, Khin Maung Maung***, May San Lwin^*** and Hnin Lwin Tun^*

Introduction

Hypertension, or high blood pressure, is the most common cardiovascular disorder affecting 20% of adult population worldwide. It is also an important public health problem of global dimensions, both in the developed and developing world1. Based on the cut-off values of hypertension (³140 mmHg for systolic blood pressure and ³ 90 mmHg for diastolic blood pressure regardless of the age), the prevalence of hypertension ranges from 8% to 18% among adults in many parts of the world. According to a previous cardio-vascular diseases survey, the prevalence of hypertension was 12.4% for rural areas and 14.5% for urban areas2. Considering the lack of information, national interest and budget limitation, this small-scale study was carried out to determine the prevalence of hyper-tension among people aged 15 years or above and to explore dietary habits, BMI, waist-hip ratio, and the biochemical levels of people with or without hypertension in selected villages of Kayin state.

Methodology

The villages selected in the study were three miles away from the city, Pa-An of Kayin state. Before starting the cross-sectional survey, the list of all people in the age group 15 years and above currently living in the selected villages (790 people) was developed with the help of local authority and used for recruitment. Those who were working in other places were not included in the list. The non-response rate was about 10%. During the survey, around 5% of respondents, who were not in the list, were recruited during their temporary stay in TYH for a village development project. Such respondents included construction workers, teachers, Red Cross members and students. After taking verbal informed consent, a total of 753 (370 in TYH and 383 in MGL) people were examined and 108 (54 with hypertension and 54 with normal blood pressure) were tested for serum cholesterol and HDL level. Medical officers measured the blood pressure by using standardized sphygmo-manometers. Firstly, all were requested to rest for at least 10 minutes before blood pressure measurement in a lying down position. This procedure was repeated one minute after the first measurement. Next, a face-to-face interview was conducted using a structured questionnaire. Then, body weight, height, waist circumference and hip circum-ference were measured using standard measuring procedures. After that, each person was included in one of the following lists:

     Systolic and diastolic hypertension with no prior anti-hypertensive treatment within two weeks;

     Normotension with no prior anti-hypertensive treatment within two weeks;

     Systolic or diastolic hypertension only, and

     Those with prior anti-hypertensive treatment regardless of current blood pressure level.

Finally, the people selected randomly from out of list (i) or (ii) were requested for their blood samples. The walk-through observation in villages and informal group discussion with eight women using guidelines were carried out with particular emphasis on dietary habits.

Informed consent

Ethical approval for conducting this study which involved humans as subjects was obtained from the Institutional Ethical Review Committee, Department of Medical Research, Lower Myanmar. Informed consent was taken in Myanmarese language. Before participation in the study, informed consent was taken from respondents by trained research assistants from the Department of Medical Research using the prepared consent form. Respondents were briefed on the purpose and procedure, including the taking of 5cc blood samples from randomly-selected respondents. The contents of the consent form made the following points clear: (i) that the participation was on a voluntary basis; (ii) the right to ask questions up to the respondent’s satisfaction; (iii) the possibility of psychological annoyance in answering some questions, and (iv) the right of respondents to withdraw from the study at any time without affecting their future health care. Respondents were also informed that they could participate in the study without having to give their blood samples. Consents were given by respondents verbally rather than in writing because village people were found to be culturally reluctant to sign. Measurements for blood pressure, height, weight, waist circumference and hip circumference were taken in separate rooms having opaque curtains by examiners of the same sex as the respondents. Although names of the respondents were documented during recruitment using the sampling frame, the name of the respondent was not written on the questionnaire form to ensure confidentiality. The interview was carried out in privacy. Blood samples were taken at a separate place in the end. Out of the 108 randomly-selected respondents for the purpose of blood samples, two refused to give their blood samples and were replaced with the persons next on the list, and the same procedure of taking informed consent was carried out. The principal investigator provided the initial drug treatment including avoidance of high salt diet to those with high blood pressure and referred them to the local health assistant for future blood pressure examination. A packet containing 10 tablets of multivitamins was given to each respondent.

Analysis

EPI-Info version 6.04 was used for double entry and validation of data and Stata version 6 was used for data analysis. Criteria of systolic blood pressure 140 mmHg and above, and diastolic blood pressure 90 mmHg and above, regardless of the age of the respondent were used for recording the hypertension status. The percentages of hypertension for different age groups, areas and sex were calculated. The BMI and waist-hip ratio were calculated. Pregnant women were excluded from calculations of the waist-hip ratio. Odds ratio were calculated for some variables of interest. Although logistic regression analysis was attempted for hypertension status, the modelling was not good enough to be included in the findings. Content analysis was done using field notes and the notes taken during informal discussions.

Results

Findings of the structured interview survey

Background characteristics

Of the total, 268(35.6%) were males and 485(64.4%) were females. The ages of respondents ranged from 15 to 82 years. The mean age was 36.6 ± 15.7 in TYH; 39.9 ± 16.6 in MGL; 38.1 ± 17.7 for males, and 38.3 ± 15.4 for females. The median of monthly family income (in kyats) was 15 000 in TYH and 10 000 in MGL. The illiteracy rate was 10%.

Hypertension and stroke

The percentages of hypertension (systolic blood pressure ³ 140 mmHg and diastolic blood pressure ³ 90 mmHg) were 22.4% for both townships; 17.3% in TYH, and 27.4% in MGL. Hypertension among different age groups (15-24 years, 25-39 years and 40 or above) were higher in MGL (7.6% vs 3.8%; 14.0% vs 11.3%; 43.7% vs 31.3%) than in TYH (Table 1). The prevalence of hyper-tension was higher among females than males (Table 2). Systolic hypertension was 3.5% and diastolic hypertension was 11.3% among total respondents, regardless of the history of having taken any anti-hypertensive drugs within the last two weeks (Table 3). Of all respondents, 16 (2.1%) reported a previous history of stroke. The age for a first-time stroke ranged from 29 to 61 years (Mean 42.5 ± 9.4).

Table 1.Percentages of hypertension (systolic ³ 140 and diastolic ³ 90 mmHg) by different age groups in the two selected villages, Myanmar, 2001

Table 2. Percentages of hypertension (systolic ³ 140 and diastolic ³ 90 mmHg) among males and females by age groups and by villages, Myanmar, 2001

^*For respondents 15 years and above

Table 3. Percentages of different types of hypertension among both males and females
 in the two selected villages, Myanmar, 2001

Personal habits (smoking, alcohol and toddy palm juice)

The percentages for personal habits for both males and females in the three age groups were: 34.13%; 53.7%, and 23.3% respect-tively for smoking; 18.19%; 47.0%, and 2.3% respectively for alcohol drinking, and 30.81%; 60.1%, and 14.6% respectively for toddy palm juice drinking. The percentages for hypertension among ever-smokers, alcohol drinkers and toddy palm juice drinkers were 27.6%; 27.0%, and 21.1% respectively. The number of alcohol bottles consumed in one year by hypertensive alcohol drinkers was higher than the number of bottles consumed by normotensive alcohol drinkers (median 91.2 vs 26; mean 143.07 ± 184.9 vs 79.8 ± 185.9). Similarly the number of bottles consumed by hypertensive toddy palm juice drinkers was also found to be higher than that consumed by normotensive toddy palm juice drinkers. (median 18 vs 12; mean 175.4 ± 400.0 vs 171.35 ± 544. 6).

Measurement of blood pressure and use of anti-hypertensive drugs

Of all, 516 (68.5%) persons were found to have ever taken blood pressure measurement in life. Among them 145 (28.1%) had been told by the doctor at least once of having hypertension. And out of these 145 persons, 103 (71.03%) had been informed of having high blood pressure by the doctor at least on two occasions. Out of the 145 persons mentioned above, only 127 (87.6%) had ever been given treatment for hypertension. Two thirds (66.5%) of those who had been given treatment mentioned that they were regularly taking anti-hypertensive treatment, while 31(24.4%) reported having taken anti-hypertensive treatment during the previous two weeks, whereas the remaining majority (75.6%) reported not having taken any treatment during the previous two weeks only seven persons reported that they were taking treatment daily.

Two thirds (68.5%) of respondents reported having been told of the total duration of treatment to be taken by the health staff. The mean duration of treatment that had been given to understand by the health staff was 8.1±17.5 days and the median duration was three days. Two thirds (65.6%) took treatment for less than three days and only 3.4% took treatment for one or more months. None of them took treatment beyond four months.

Of those with a history of hypertension, 29% reported having taken traditional medicine and 97.2% reported having been advised by health staff to reduce their salt intake. Among alcohol drinkers with hypertension, 57% were advised to reduce their salt intake. About 8% of respondents with hypertension reported having been advised by health staff for exercise. Only 9% of those with high waist-hip ratio reported having been told to reduce weight.

Serum cholesterol and HDL measurement

Of the 108 people (54 with hypertension and 54 with normal blood pressure) examined for serum cholesterol and HDL levels, eight (five in normotensive group and three in hypertensive group) had higher levels of cholesterol (³250mg%). As shown in Table 4, the mean and median of serum cholesterol levels in the hypertensive group were slightly higher than those for the normotensive group.

Table 4. Serum cholesterol and HDL level among the hypertensive and normotensive groups, Myanmar 2001

Dietary habit

Out of the total study population, only 5.7% mentioned that they never ate ngapi (salted fish paste) during the past 12 months, while about half (49.2%) the population reported eating ngapi two or more times per day. However, no association was found between ngapi consumption and hypertension in this study. At the same time, 91.7% (97% in TYH and 87% in MGL) people reported having eaten dried fish during the past 12 months and 68% reported eating dried fish less than ten times a month. The daily dried fish consumption was 6% for both villages (11% in Ta-Yoke-Hla and less than 1% in MGL). One fifth (21%) of the population never drank coffee during the past 12 months, while about 20% of the population drank coffee daily with 75% of them drinking at least once a day. The correlation coefficients were found to be very small (<0.2) between systolic blood pressure and frequency of consumption of ngapi, dried fish, coffee, myanmar medicine for digestion ("yet-sar") and liquorice.

BMI and waist-hip ratio

The overall percentages for high BMI (³ 25) were 3.8% for both sexes: 1.1% for males and 5.4% for females. The percentage of hypertension among the high BMI group (17.2%) was found to be non-significantly lower than the normal BMI group (22.6%).

Among males, the percentage of high waist-hip ratio (³ 0.95) was 9.9% and the proportion of hypertension among them (12.5%) was non-significantly lower than others (18.9%). Among females, 61.4% were found to have high waist-hip ratio (³ 0.85) and the proportion of hypertension was higher among them (30.6%) than the rest (15.0%). The mean waist-hip ratio among males and females were not significantly different for persons with or without hypertension (0.87±0.05 vs 0.86±0.05 for males; and 0.89±0.06 vs 0.87±0.07 for females).

Odds ratios for some variables of interest

Age, years of schooling, smoking habit of respondents and the history of stroke in mothers were found to be significant (Table 5).

Findings of informal discussions and observations

All participants during informal discussions mentioned that dizziness and sudden fainting attacks were the main symptoms of hypertension, and that blood pressure should be checked for diagnosis. High fat, salty diet and mental stress (e.g. anger) were mentioned to be the main causes. Although some mentioned the possible rupture of a blood vessel in the brain as a complication, none could express its consequences on the heart, the kidney and eyes.

Table 5.Crude odds ratio and 95% confidence intervals for outcome variable
hypertension among 753 respondents
Myanmar 2001

Despite the fact that some respondents mentioned eating low-salt diet; reduction of mental stress, and meditation as factors that could reduce blood pressure, it was found that they ate high amounts of ngapi made from fish in TYH or from the residue of sesame or groundnut skin in MGL.

"Ngapi is essential for us. Though it may increase blood pressure, it is cheap and hence, we, as poor people, have to eat it.” 

"Fish is mixed with salt, kept in the sun and pounded to make ngapi.” 

"Child starts to eat ngapi when he is one year old. Older people consume ngapi daily in meals, along with gourd or tomatoes.”

The use of monosodium glutamate was lesser than before. Men and some women were used to drinking toddy palm juice and alcohol at ceremonies like weddings and funerals. Betel-chewing had become popular, as compared to the practice of keeping tobacco leaves in the mouth. Furthermore, the use of liquorice and tobacco leaves in combination with betel was common.

During the walk-through sightseeing, the villagers were found to be eating meals with ngapi, and making ngapi and children were found to be eating dried fish as a snack. Grocery shops sold dried fish as staple food and betel shops stocked bundles of liquorice sticks.

Discussion and conclusion

Our study found that percentages of hypertension in different age groups in the study area were high, particularly in the MGL village. This may be due to the racial differences in groups of these two villages. The Bamar people and Mon descendents live in TYH, while people of Pa-Oh origin are mainly living in MGL. Although they were found to be very similar in the practice of eating salty diet, there may be some factors which we have not been able to explain in this study and which may play a role in the difference in prevalence. The overall prevalence of hypertension in our study (22.4%) was found to be slightly higher than that of the previous study (21.9%) in Ka-naung village³ in Myanmar. The percentage of these treated adequately was lower than in the previous study of the urban area of Bago in Myanmar in which half of those diagnosed were found to be taking treatment and one forth of them were adequately treated⁴. This may be due to the fact that our study area covered the rural villages where the health staff were of a level lower than in the urban areas. The incidence of stroke was noticeable from our study, although reasons other than hypertension causing a stroke could not be excluded.

The high intake of salty diet, liquorice and tobacco leaves may be related to the high prevalence of hypertension although a significant association between hypertension and these factors was not found in this study. As is well known, this study also found a significant association between age and hypertension. The association of smoking and hypertension (OR=1.5) in univariate analysis was also found to be true as per the well-known effect of smoking on the cardiovascular system.

A previous study reported that blood pressure rises with excess sodium intake, low HDL, and increase in BMI^3,5 and the waist-hip ratio^3,6. The lack of association between hypertension and other factors, such as serum cholesterol level, HDL level, dietary habits, BMI and waist-hip ratio may be due to the small sample size and to some extent, to sampling bias. The higher proportion of females than males in sample selection may be due to the fact that males travel more than females.

Our study findings indicate that health education involving hypertension should include: seriousness of taking regular anti-hypertensive treatment; the complications for different organs; cessation or reduction of smoking and alcohol drinking; effect of exercise, and reduction of salt intake. The ways and means at avoiding the traditional high-salt diet and the daily consumption of ngapi among the poor should be explained. The prevalence of hypertension among different ethnic groups should also be explored.

Acknowledgements

We would like to express our sincere thanks to Professor Dr Paing Soe, Director-General, Department of Medical Research (Lower Myanmar) for encouragement and permission to conduct this study.

References

1.      WHO, The World Health Report 1997. Hypertension. p 39-45.

2.      Ministry of Health, National Health Plan, 1996-2000.

3.      Report of the hypertension status of people in Kanaung village, Kyauk-Tan township by DMR, Lower Myanmar, 2001 Jan (Myanmar Language).

4.      M.Med.Sc.(Thesis) Thet Thet Mu. Factors associated with hypertension and hypertension awareness among the 40-years-and-above age group of urban population in Bago.

5.      Jousilahti P, Tuomilehto J, Vartiainen E, Valle T, Nissinen A. Body mass index, blood pressure, diabetes and the risk of anti-hypertensive drug treatment: 12-year follow-up of middle-aged people in eastern Finland. Journal of human hypertension 1995 Oct; 9(10): 847-54.

6.      Ming J et al. Relationship between weight and body fat's distribution and ambulatory blood pressure in Chinese elderly. Clinical and experimental hypertension 1994 Sep; 16(5): 545-63.