Hypertension in Vietnam: prevalence, risk groups and effects of salt substitution

ABSTRACT

Background: Over the past decades, the morbidity and mortality patterns have changed rapidly in Vietnam, with a reduction in infectious diseases in parallel with a rapid increase in non-communicable diseases (NCDs), leading to the so-called double burden. It was estimated that in 2008 NCDs accounted for 75% of all deaths in Vietnam, and cardiovascular diseases were the leading cause accounting for 40% of total mortality. Hypertension is one of the major risk factors for cardiovascular disease, but information on the nationwide prevalence and main determinants is lacking. There is an urgent need for appropriate population-based interventions for hypertension control and prevention in Vietnam.

Methods and Results: Data of 17,213 adults aged 25-64 years from the nationally representative 2005 National Adult Obesity Survey were used to study the prevalence of hypertension and prehypertension and their determinants. The overall prevalence of hypertension was 20.7% and the prevalence of prehypertension was 41.8%. Hypertension and prehypertension were more prevalent in men than in women (25.2% vs. 15.9%). Determinants of raised blood pressure including advancing age, overweight, alcohol use (among men), and living in rural areas (among women) were independently associated with a higher prevalence of hypertension, whereas higher levels of physical activity and education were inversely associated. Age, body mass index (BMI), and living in rural areas were independently associated with an increased prevalence of prehypertension. Among the hypertensives, only 25.9% were aware of having hypertension and 12.2% were treated. Among the treated hypertensives, 32.4% had their blood pressure controlled.

Overweight and obesity, important risk factors for hypertension, were investigated using data of 14,452 Vietnamese adults aged 25-64 years from the nationally representative 2000 National Nutrition Survey and data of 17,213 adults aged 25-64 years from the nationally representative 2005 National Adult Obesity Survey. The results showed that the distribution of BMI across the population and in population subgroups indicated a shift towards higher levels in 2005 as compared to 2000. The nationwide prevalences of overweight (BMI ≥ 25 kg/m2) and obesity (BMI ≥ 30 kg/m2) were 6.6% and 0.4% respectively in 2005, almost twice the rates of 2000 (3.5% and 0.2%). Using the Asian BMI cut-off of 23 kg/m2 the overweight prevalence was 16.3% in 2005 and 11.7% in 2000. Women were more likely to be both underweight and overweight than men in both 2000 and 2005. Urban residents were more likely to be overweight and less likely to be underweight as compared to rural residents in both years. The shifts from underweight to overweight were more pronounced in those with higher food expenditure levels.

A survey on sodium intake among a rural community near Hanoi (n=121) showed that mean 24-hour sodium excretion was 188.6 ± 57.5 mmol (4.3g), which corresponds to an intake of salt (sodium chloride) of 10.8 ± 3.3 g/day. Men had a higher mean sodium excretion (196.8 ± 56.9 mmol/day or 4.5g/day) than women (181.1 ± 57.4 mmol/day or 4.2g/day); 97.5% of the men and women had a salt intake higher than the World Health Organization’s recommendation of < 5g/day. Subjects with complete urine collection had a salt excretion of 11.7 g/day. Sodium in condiments added during cooking or eating at the table accounted for 81% of sodium intake. Processed foods contributed 11.6% and natural foods 7.4%. Regarding the condiments, the largest source was the mixed seasoning (35.1% of total); 31.6% of total dietary sodium was provided by fish sauce, 7.4% by monosodium glutamate and 6.1% by table salt.

Sodium-reduced and potassium-enriched salt and ‘bot canh’, a traditional seasoning, were experimentally produced and underwent organoleptic testing, which showed high acceptance. An 8-week randomized double-blind  trial was carried out in 173 men and women between 45 and 64 years of age with untreated (pre)hypertension in a rural Vietnamese community. The intervention group that received sodium-reduced and potassium-enriched condiments (salt and bot canh) experienced a median 24-hour sodium excretion decrease of 28.5 mmol/d (1.6 g/d salt) compared to the control group that received regular condiments for home food preparation and dining. The mean change in BP in the intervention compared to the control group was -2.6 mmHg (95% CI: -4.6 to -0.5, p = 0.013) for systolic BP and -1.6 mmHg (95% CI: -3.0 to -0.2, p= 0.024) for diastolic BP. The prevalence of iodine deficiency was significantly reduced in both groups (from 66% to 41% in the intervention group and from 72% to 36% in the controls).

Conclusion: Hypertension and prehypertension are prevalent in Vietnam, but awareness, treatment, and control are low. Lifestyle modifications, including the prevention of overweight, and the promotion of physical activity, particularly in urban areas, and the reduction of high alcohol consumption in men, may help to prevent hypertension in Vietnam. Between 2000 and 2005, BMI in the population shifted towards higher levels, especially in those with higher food expenditure levels, but under nutrition was also still prevalent in 2005. Most dietary sodium (81%) comes from adding salty condiments during food preparation or at the table. Therefore, limiting condiments added during cooking and at the table should be given priority. Alternatively, regular condiments may be replaced with sodium-reduced and potassium-enriched salt and ‘bot canh’ to lower BP in (pre)hypertensive Vietnamese adults. Salt iodization should be reconsidered to ensure adequate iodine intake of the population.

 

 

TABLE OF CONTENTS

 

 

Chapter 1

General introduction

1 - 24

Chapter 2

National prevalence and associated risk factors of hypertension and prehypertension among Vietnamese adults.

American Journal of Hypertension, Epub ahead of print  2014/05/28

25 - 44

Chapter 3

Nationwide shifts in the double burden of overweight and underweight in Vietnamese adults in 2000 and 2005: two national nutrition surveys.

BMC Public Health 2011, 11:62

        45 - 66

Chapter 4

Sodium intake and its dietary sources in Vietnamese rural adults

Submitted

67 - 80

Chapter 5

Sodium-reduced and potassium-enriched condiments reduce sodium intake and blood pressure in Vietnamese adults: a randomized controlled trial.

Submitted

81 - 100

Chapter 6

General discussion

 

101 - 120

Summary

 

Summary in Dutch

 

Summary in Vietnamese

 

Acknowledgment

 

About the author