UMEÅ UNIVERSITY MEDICAL DISSERTATIONS New Series No. 1018- ISSN 0346-6612- ISBN 91-7264-049-9 From Epidemiology and Public Health Sciences, Department of Public Health and Clinical Medicine, Umeå University, SE-901 87 Umeå, Sweden Epidemiology of cardiovascular disease in rural Vietnam Hoang Van Minh Umeå 2006 Umeå International School of Public Health, Epidemiology and Public Health Sciences, Department of Public Health and Clinical Medicine, Umeå University, Umeå, Sweden and Faculty of Public Health, Hanoi Medical University, Hanoi , Vietnam Copyright : Hoang Van Minh Cover design: Mahesto Danar Dono Printed in Sweden by Print & Media, 2006:2001703 Epidemiology and Public Health Sciences Department of Public Health and Clinical Medicine Umeå University, SE-901 87 Umeå, Sweden ABSTRACT In the context of transitional Vietnam, although cardiovascular disease (CVD) has been shown to cause a large burden of mortality and morbidity in hospitals, little is known about the magnitude of its burden, risk factor levels and its relationship with socio-demographic status in the overall population. This thesis provides a preliminary insight into population-based knowledge of the CVD epidemiology in rural Vietnam and contributes to the development of methodologies for monitoring it. The ultimate goal of the work is to facilitate the formulation of evidence-based health interventions for reducing the burden of the CVD epidemic in Vietnam and elsewhere.
This work was located in Bavi district, a rural community in the north of Vietnam. Studies on cause-specific mortality and risk factors were conducted within the framework of an ongoing Demographic Surveillance System (DSS) (called FilaBavi). The cause-specific mortality study used a verbal autopsy (VA) approach to identify causes of death in FilaBavi during 1999-2003. The risk factor study, conducted in 2002, employed the WHO STEPwise approach to surveillance of non-communicable disease (NCD) risk factors (WHO STEPS).
Findings indicated that Bavi district, as an example of rural Vietnam, was already experiencing high rates of CVD mortality and associated risk factors. Mortality results indicated a substantial proportion of deaths due to CVD, which was the leading cause of death (20% and 25.7% of total mortality in 1999 and 2000, respectively and 32% of adult deaths during 1999-2003), exceeding infectious diseases. Hypertension was found to be a serious problem in terms both of its magnitude (14% of the population) and widespread unawareness (82% of the hypertensives). Smoking prevalence was very high among men (58% current daily smokers) and might be expected to cause a considerable number of future deaths without urgent action.
CVD mortality and some risk factors seemed to be rising among disadvantaged groups (women, less educated people and the poor). The combination of DSS and WHO STEPS methodologies was shown to have potential for addressing basic epidemiological questions as to how NCD and CVD mortality and associated risk factors are distributed in populations. Given this evidence, actions to prevent CVD in Bavi and similar settings are clearly urgent. Interventions should be comprehensive and integrated, including both primary and secondary approaches, as well as policy-level involvement.
Further studies, continuing on similar lines, plus qualitative approaches and deeper cross-site comparisons, are also needed to give further insights into CVD epidemiology in this type of setting. Key words: Cardiovascular disease, epidemiology, risk factors, rural Vietnam i ABBREVIATIONS AIDS Acquired Immunodeficiency Syndrome CHC Commune Health Center CI Confidence Interval CVD Cardiovascular Disease DALY Disability Adjusted Life Year DBP Diastolic Blood Pressure DSS Demographic Surveillance System FilaBavi Epidemiological Field Laboratory in Bavi District GDP Gross Domestic Product HIV Human Immunodeficiency Virus ICD International Statistical Classification of Diseases and Related Health Problems IMR Infant Mortality Rate INDEPTH International Network of field sites for continuous Demographic Evaluation of Populations and Their Health in developing countries JNC Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure MOH Ministry of Health MONICA Multinational Monitoring of Trends and Determinants in Cardiovascular Diseases NCD Non-communicable disease OR Odds Ratio P P-value PPP Purchasing Power Parity RR Relative Risk SAREC Swedish Agency for Research Co-operation with Developing countries SBP Systolic Blood Pressure SES Socio-Economic Status Sida Swedish International Development Agency STEPS Stepwise approach to surveillance of non-communicable risk factors TB Tuberculosis U5MR Under Five Mortality Rate UNDP United Nations Development Programmes US$ US Dollars VA Verbal Autopsy VND Vietnamese currency (1 US$ = 15,900 VND approximately) WHO World Health Organization ii ORIGINAL PAPERS This thesis is based on the following original papers: I. Ng N, Minh HV, Tesfaye F, Bonita R, Byass P, Stenlund H, Weinehall W, Wall S. Combining risk factor and demographic surveillance – potentials of the WHO STEPS and INDEPTH methodologies for assessing epidemiological transition.
Scandinavian Journal of Public Health 2006, 34:199-208. Huong DL, Minh HV, Byass P. Applying verbal autopsy to determine cause of death in rural Vietnam. Scandinavian Journal of Public Health 2003; 31 (Suppl 62): 19- 25.
Minh HV, Huong DL, Wall S, Chuc NTK, Byass P. Cardiovascular disease mortality and its association with socio-economic status: findings from a population-based cohort study in rural Vietnam, 1999-2003. Preventing Chronic Disease 2006, in press. Minh HV, Byass P, Chuc NTK, Wall S.
Gender differences in prevalence and socio- economic determinants of hypertension: findings from the WHO STEPS survey in a rural community of Vietnam. Journal of Human Hypertension 2006; 10:109-115. Minh HV, Ng N, Tesfaye F, Byass P, Bonita R, Stenlund H, Weinehall L, Wall S. Smoking epidemics and socio-economic predictors of regular use and cessation: findings from WHO STEPS risk factor surveys in Vietnam and Indonesia.
Internet Journal of Epidemiology 2006, in press. The original papers are reprinted in this thesis with permission from the publishers. iii TABLE OF CONTENTS ABSTRACT ---------------------------------------------------------------------------------------------------------i ABBREVIATIONS-----------------------------------------------------------------------------------------------ii ORIGINAL PAPERS -------------------------------------------------------------------------------------------iii INTRODUCTION------------------------------------------------------------------------------------------------ 1 What is cardiovascular disease? --------------------------------------------------------------------------------- 1 Cardiovascular disease: an emerging public health problem in developing countries--------- 2 Epidemiological transition----------------------------------------------------------------------------------------- 3 The case of Vietnam ------------------------------------------------------------------------------------------------- 6 STUDY OBJECTIVES------------------------------------------------------------------------------------------13 MATERIALS AND METHODS-----------------------------------------------------------------------------14 Study setting ----------------------------------------------------------------------------------------------------------14 Study base -------------------------------------------------------------------------------------------------------------16 Study design ----------------------------------------------------------------------------------------------------------19 Main definitions------------------------------------------------------------------------------------------------------24 Ethical considerations ----------------------------------------------------------------------------------------------25 MAIN FINDINGS ----------------------------------------------------------------------------------------------26 Applying VA and the WHO STEPS methods in FilaBavi (I, II) ---------------------------------------26 Burden of mortality from CVD in Bavi (II, III) -------------------------------------------------------------27 Magnitude of selected CVD risk factors among adults in Bavi (I, IV, V) --------------------------29 Social patterning of CVD mortality and risk factors in Bavi (III, IV, V) ----------------------------31 Comparing risk factors profile among adults in 3 INDEPH sites (I, V) ----------------------------34 DISCUSSIONS --------------------------------------------------------------------------------------------------39 Potential of combining the DSS and the WHO STEPS methodologies -----------------------------39 Burden of CVD mortality and its risk factors in Bavi ----------------------------------------------------41 Social patterning of CVD mortality and risk factors in Bavi -------------------------------------------44 Risk factors transition in three transitional societies -----------------------------------------------------48 Methodological considerations----------------------------------------------------------------------------------49 CONCLUSIONS AND POLICY IMPLICATIONS-----------------------------------------------------52 ACKNOWLEDGEMENTS------------------------------------------------------------------------------------57 REFERENCES ----------------------------------------------------------------------------------------------------61 APPENDIX --------------------------------------------------------------------------------------------------------68 INTRODUCTION INTRODUCTION What is cardiovascular disease? Cardiovascular disease (CVD) is the term used by the scientific community to embrace not just conditions of the heart (coronary artery, valvular, muscular, and congenital disease), but also hypertension and conditions involving the cerebral, carotid and peripheral circulation [1]. According to the International Statistical Classification of Diseases and Related Health Problem 10th revision (ICD 10) [2], CVD comprises many conditions including the following: • (I00-I02) Acute rheumatic fever • (I05-I09) Chronic rheumatic heart diseases • (I10-I15) Hypertensive diseases • (I20-I25) Ischaemic heart diseases • (I26-I28) Pulmonary heart disease and diseases of pulmonary circulation • (I30-I52) Other forms of heart disease (pericardium, endocardium including heart valves, myocardium/ cardiomyopathy, electrical conduction system of the heart, other) • (I60-I69) Cerebrovascular diseases • (I70-I79) Diseases of arteries, arterioles and capillaries • (I80-I89) Diseases of veins, lymphatic vessels and lymph nodes, not elsewhere classified • (I95-I99) Other and unspecified disorders of the circulatory system CVDs vary in the extent to which they compromise normal circulation; some CVD events such as heart attacks or strokes may be rapidly fatal, while people with rheumatic heart disease and other chronic CVD often survive for long periods along with heart attack and stroke survivors, leading to a considerable burden of prolonged illness and disability.
1 INTRODUCTION Cardiovascular disease: an emerging public health problem in developing countries CVD has been an important health issue in developed countries for some decades, while in developing countries it has often not been seen as a major problem compared with communicable diseases and malnutrition [3]. However, current trends in the CVD epidemic show diversification into two contrasting directions. In at least some developed countries, the CVD epidemic is decreasing as a result of major efforts to identify risk factors and implement interventions [4]. Meanwhile, in many developing countries, CVD and related risk factors are emerging as increasingly important public health problems [5-14].
In fact, twice as many deaths from CVD have occurred in developing countries as in developed countries [15]. CVD accounts for a huge proportion of human illness and death, estimated to cause about 17.5 million deaths worldwide annually (30% of total deaths), with low and middle-income countries carrying 80% of the CVD mortality burden. CVD is killing more middle-aged people in poorer countries than in wealthier ones and affecting five times as many people as HIV/AIDS in developing nations [16]. According to the Global Burden of Disease Study, CVD is expected to cause more than 19 million deaths annually in developing countries by 2020 [4].
There will be a 55% rise would occur in DALY (Disability Adjusted Life Years) lost attributable to CVD between 1990 and 2020 in developing countries [4]. CVD will affect all socio-economic groups and inflict major economic and human cost. Clinical care of CVD is costly and prolonged. These direct costs divert scarce family and societal resources to medical care.
CVD often affects individuals in their peak mid-life years, disrupting the future of the families dependent on them and undermining national development by depleting valuable human resources in the most productive years [17]. Not only is the burden of CVD in developing countries increasing, but the burden of its risk factors is also increasing [18]. A few major risk factors, such as tobacco use [18, 2 INTRODUCTION 19], elevated blood pressure [18, 20], imbalance diet [18, 21], physical activity [18, 22, 23] and alcohol consumption [18, 24], etc, explain a large proportion of new cases of CVD. It has been estimated that among people aged 30 years old and over, 50% of CVD is related to elevated blood pressure, 31% to high cholesterol and 14% to tobacco use [18].
The rising burden of CVD and its risk factors will have health, social and economic consequences, and will have an impact on national development. As health care systems in developing countries are usually designed to deal with acute communicable diseases, a growing CVD burden will be a major challenge in these countries today and in the future [12, 16, 25-28]. Epidemiological transition The theoretical basis for explaining the emerging CVD epidemic in developing countries is that of the “epidemiological transition” formulated by Abdel Omran [29, 30]. The epidemiological transition theory is the framework for describing and explaining “a characteristic shift in the disease pattern of a population as mortality falls during the demographic transition: acute, infectious diseases are reduced, while chronic, degenerative diseases increase in prominence, causing a gradual shift in the age pattern of mortality from younger to older ages” [29].
Omran originally defined three stages of epidemiological transition: 1 - the “age of pestilence and famine”, 2 - the “age of receding pandemics”, 3 - the “age of degenerative and manmade disease [29]. Thirty years later, Omran proposed two more stages for the western model: 4 - the “age of declining CVD mortality, ageing, life style modification, emerging and resurgent diseases” and 5- the “age of aspired quality of life, with paradoxical longevity and persistent inequities” [30]. Omran also proposed a different third stage for non-western countries, “the age of triple health burden”, i. the unfinished old set of health problems, a rising new set of health 3 INTRODUCTION problems, and the ill-prepared health systems to cope with the prevention and care of chronic diseases [30].
While the epidemiological transition progressed slowly over a century in the developed world, it appears to be accelerating faster in some developing countries.