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Indian Journal of Community Medicine

Continuing Medical Education-Prevention of Coronary Heart Disease in India: An Epidemiological Perspective

Author(s): Rajeev Gupta, Prakash C. Deedwania, M.R. Soangra

Vol. 27, No. 4 (2002-10 - 2002-12)

World Health Organisation (WHO) has defined primary prevention of coronary heart disease (CHD) as prevention of its first events, beginning early in childhood and continuing throughout childhood, youth and adult life. Primordial prevention is defined as prevention of risk factors themselves beginning with change in social and environmental conditions in which these factors are observed to develop and continuing for high risk children, adolescents and young adults1. Prevention of CHD has become a reality following successes in high-risk populations in Finland in 1970's. In USA and many developed countries impressive achievements have been made in reducing deaths from cardiovascular diseases. Age-adjusted CHD mortality has decreased by more than 40% in last 25 years in USA2. This has been attributed to population based preventive measures along with high risk treatment approach, employing suitable primary prevention techniques, better treatment of these conditions and secondary prevention strategies in the recovery phase.

Demographic shift in population age-profile combined with lifestyle related increase in cardiovascular risk factors are accelerating CHD epidemic in India3-5. CHD prevalence in urban populations increased from 3.5% in 1960's to 9.5% in 1990's. In rural areas it increased from 2% in 1970's to 4%6. Epidemiological evolution of cardiovascular diseases is classified into six stages derived from population levels of acculturation, urbanisation, affluence, saturated-fat intake, salt intake and smoking7. The prevalence of CHD initially increases with a rise in these factors, then stabilises and finally decreases. In India, these social and economic indices of epidemiological transition explain the increasing CHD prevalence4,5.

CORONARY RISK FACTORS IN INDIANS: LESSONS FROM EPIDEMIOLOGICAL STUDIES

Prevention is based on control of atherosclerosis risk factors. Framingham Heart Study in USA played vital role in identifying the risk factors for CHD incidence in general population8. Major risk factors are cigarette smoking, hypertension, high serum cholesterol, low levels of high density lipoprotein (HDL) cholesterol, and diabetes mellitus. Other factors are obesity, physical inactivity, family history of premature CHD, insulin resistance syndrome, hypertriglyceridaemia, increased lipoprotein (a), increased serum homocysteine and abnormalities in several coagulation factors. Clustering of several metabolic risk factors in a single patient is termed as the metabolic syndrome8. This syndrome is characterized by atherogenic dyslipidaemia (borderline high LDL cholesterol, raised triglycerides and dense LDL, low HDL cholesterol), hypertension, peripheral insulin resistance, non-insulin dependent diabetes and a procoagulant state. Psychosocial and socio-economic factors are also important.
Prospective cohort studies for evaluation of coronary risk factors do not exist in India. Surely, we need well designed prospective studies. However, we can learn from the epidemiological studies performed so far to initiate preventive efforts. Studies have clearly shown that CHD is a significant problem in India6. Coronary risk factors such as hypertension, smoking, physical inactivity, obesity, truncal obesity and improper diet leading to hypercholesterolaemia and hypertriglyceridaemia are fairly widespread5. There is age related increase in CHD in India6 and the anatomical and pathological pattern of atherosclerosis is not very different from countries where CHD is endemic9. However, onset of CHD in younger age is a cause for concern6. Genetic factors that are modified by environment could be important.

Table I: Coronary risk factors in emigrant south Asians.

Risk factors similar in South Asians and Caucasians
Hypertension
Smoking
Body-mass index and obesity
Total cholesterol
Apolipoprotein B levels
Risk factors more in South Asians
Sedentary lifestyle
Truncal obesity
Insulin resistance and hyperinsulinaemia
Lipoprotein(a) levels
Hypertriglyceridaemia
HypoHDLcholesterolaemia
Increased plasminogen activator inhibitor-1 activity
Low tissue plasminogen activator activity

Studies among emigrant South Asians provide important clues regarding risk factors of importance. Williams recently summarised factors which are more in South Asians compared to Caucasians (Table I) and highlighted the role of physically active lifestyle in ameliorating many of these10. Urban-rural differences in prevalence of coronary risk factors among Indians provide important information regarding risk factors that need prevention.

Table II: Coronary risk factors that are greater in urban Indians.
Sedentary lifestyle
Hypertension
Body-mass index, obesity
Waist:hip ratio, truncal obesity
Total and LDL cholesterol, hypercholesterolaemia
Triglycerides levels
Fasting insulin levels, insulin resistance

Padmavati et al11 in 1960's and Gupta et al12 in 1970's performed comparison of CHD risk factor prevalence in urban and rural populations in Delhi and Haryana respectively. CHD prevalence in urban subjects was twice that of the rural. These studies showed greater prevalence of hypertension, obesity, sedentary lifestyle and total cholesterol levels in urban subjects. Reddy et al3 and Chaddha et al13 in Delhi and Gupta et al14,15 in Rajasthan also performed urban-rural comparisons in coronary risk factor prevalence. These studies showed that in addition to hypertension, cholesterol levels and obesity, factors such as glucose intolerance, diabetes, truncal obesity and hyperinsulinaemia were also more in the urban subjects. Case-control studies of coronary risk factors in CHD patients confirm these findings16. Comparative studies of emigrant South Asians also provide similar results10.17,18. Therefore, coronary risk factors which are more common in urban Indians and are associated with a greater prevalence of CHD in case control studies are important (Table II) and should be targets for prevention.

Primordial prevention:

To achieve the goal of preventing cardiovascular diseases it is important to change the milieu that promotes major risk factor development. Primordial prevention calls for changing the socio-economic status of society. Better social, economic and cultural statuses correlate inversely with lifestyle factors of smoking, abnormal food patterns and exercise14.

WHO recommends changes in attitudes, behaviour and social values for primordial prevention of CHD1. These are encouragement of positive health behaviour, prevention of adopting risk behaviour, elimination of established risk behaviour and promotion of the concept of health as a social value. Established principles and practices of health and general education should be included in public health programmes. Healthy behaviour should be made socially acceptable and encouraged by improved community facilities. The decisive role of health education in schools to be stressed through new social and behavioural values. Close co-operation between the heath and teaching profession at all levels is needed. Special target groups, viz., children and adolescents, the family unit, the under privileged and other high risk groups to be approached. The mass media should play major role in health education programme. 

Primordial prevention begins in childhood when health risk behaviour begins19. Parents, teachers and peer groups are important in imparting health education to children. In Indian adolescent school children there is a high prevalence of obesity, hypertension, hypercholesterolaemia and high fat diet20.

Promotion of dietary restriction, physically active lifestyle and avoidance of tobacco use beginning from childhood is important for primordial prevention. All adults should know their blood pressure and blood cholesterol levels, should not smoke, should monitor their salt and fat intake and should engage in at least moderate exercise. Medical practitioners should incorporate into clinical practice the advances achieved by research for the care of patients with cardiovascular diseases.

Primary prevention:
The recent decline in cardiovascular diseases in developed countries is attributed to reversal of those factors which precipitated this epidemic2. Cigarette smoking that spread widely in the first half of the century is now decreasing. Hypertension, once widely undetected, is now routinely detected and treated. Mass hyperlipidaemia is now less common due to widespread dietary change and better detection and treatment of elevated lipids. Improvements in the treatment of patients with cardiovascular diseases have resulted in improved survival. In India, there is an urgent need for a national health policy that will integrate population based measures for CHD risk factor modification along with cost-effective case management for individuals at high risk for developing CHD.

Population strategy:

Rose initially suggested that a population approach to prevention is important21. He identified that population means reflect deviant individuals. Higher the mean, greater would be the prevalence of that condition. Mean blood pressure of a population accurately predicts the number of hypertensive individuals and mean body weight predicts the number of obese subjects. He also identified that the prevalence of a high risk state (hypercholesterolaemia, hypertension, obesity, etc.) is largely a reflection of the lifestyles and attitudes of the masses. Population wide approach corrects the underlying cause of the epidemic and is safer, cheaper and more cost-effective than the high risk corrective approach21.

Epidemiological studies have identified that many traditional coronary risk factors (Table II) are important in Indians. Adopting healthier lifestyles as norms for the entire population can change most of these factors. We propose following lifestyle changes that are applicable especially to urban Indians.

  • Reduction of salt, alcohol and calorie intake, exercise, stress management and greater intake of calcium, potassium, magnesium and fibre can prevent hypertension22.
  • Control of hypercholesterolaemia and decrease in mean LDL cholesterol levels can be achieved by reducing intake of saturated fats, meat and dairy products and greater intake of polyunsaturated fats and fibre.
  • Low HDL cholesterol levels can be influenced by greater intake of monounsaturated fats, fruits, green vegetables and exercise.
  • Truncal obesity and insulin resistance can be reduced by regular exercise.
  • Smoking control requires a variety of measures including, but not limited to23, restrictions on smoking in the workplace and in public, enhanced community education programmes and physician supervised counselling on smoking cessation.

Behavioural and environmental changes in the whole population that are relevant to these risk factors are changes in eating patterns, drinking and smoking, increased physical activity and modulation of psychosocial factors1.

High risk approach:

South Asian race has been mentioned an atherosclerosis risk factor corollary to the observation of high CHD mortality in this group. Thus all Indians should be targeted for primary prevention. Specific high risk subjects are those with family history of CHD, hypertension or diabetes or those having sedentary lifestyle, obesity, truncal obesity or other coronary risk factors. The high risk approach depends directly on practising physicians and other health care workers. There should be an active interest on the part of physicians to teach, a willingness on the part of patients to accept and act on preventive advice and acceptance by governments and health insurance schemes that the cost of preventive services, like that of curative care, should be fully reimbursed. For high risk strategy, guidelines are needed for detection and management of high risk individuals8. These should specify the measurements and observations to be recorded, the criteria to be used to identify individuals requiring further evaluation and management procedures, including both appropriate interventions and goals by which their effectiveness can be monitored.

Table III: Risk reducation strategies for high risk Indian subjects.

Smoking
Complete cessation
Lipid management
Primary goal: LDL <100 mg/dl
Secondary goal: HDL >35 mg/dl, triglycerides <200 mg/dl
Start AHA step II diet in all patients: <30% fat,
<7% saturated fat, <200 mg cholesterol/day
Consider drug therapy when LDL >100 mg/dl.
Definite drug therapy when LDL >130 mg/dl
Physical activity
Minimum physical activity is >30 minutes of
moderate intensity,
3-4 times per week (walking, jogging, cycling
or other aerobic activity)
Weight management
Maintain <120% of ideal weight for height
Maintain waist: hip ratio <0.90 in men and <0.80 in women
Blood pressure
Goal <140/90 mmHg
Initiate lifestyle modification in all patients
with hypertension
Drug therapy when required

Screening will ordinarily include measurement of total cholesterol, systolic and diastolic blood pressure, height and weight and aerobic fitness. Subjects should be questioned regarding tobacco use and dietary history. American Heart Association recently published guidelines for prevention of CHD24. These are based on scientific evidence and demonstrate that risk factor interventions increase overall survival, improve quality of life and reduce the incidence of myocardial infarction. The interventions are smoking cessation, lipid management, physical activity guidelines, weight management and blood pressure control (Table III).

Conclusions:

In summary, coronary heart disease in India can be prevented by controlling intake of tobacco, salt, saturated fats and calories; by increasing both work related and leisure time physical activity; increasing consumption of heart healthy foods such as fruits and vegetables, high fibre cereals, oils containing balanced amounts of polyunsaturated and monounsaturated fats e.g., Canola (genetically engineered mustard-rapeseed) oil, soyabean oil and spices and cereals with high flavinoid content. Stress management techniques especially yoga may be important. Reverting to traditional Indian social lifestyles (joint families, small families and good education) is also important.

Before embarking on an ambitious prevention programme it is essential to realise the problems in its implementation. Barriers to a national cardiovascular disease prevention policy are: competing priorities with infectious diseases, lure of technology based therapeutic interventions in cardiology which relegate preventive cardiology to the periphery, inadequate CHD epidemiological data in form of cohort studies, poor presentation of messages to policy makers and the media who do not realise that CHD is preventable, discordant messages released by various vested interests, failure to recognise the importance of prevention and its cost-effectiveness, lack of peer recognition for preventive efforts, economic and social constraints, vested interest of food groups and tobacco companies and lack of community mobilisation3.

Table IV: Physicians' role in co-ordination with other sectors.

Political
Lobby for health promotion measures,
Increased funding for non-communicable research & prevention
Community organising and formation of community advisory group
Educational
Make presentations to students, collegues and media
Deliver the message effectively in newspapers, radio, television and magazines
Build media relationships
Economic
Lobby for financial incentives and reimbursement of preventive care
Medical associations
Constinuing medical education programme focus on preventive care
Association support for community efforts

The need to contain the epidemic as well as combat its impact and minimise the cardiovascular diseases toll in Indians is obvious and urgent. National strategies to meet this objective must be developed and effectively implemented. Regional and global initiatives by international agencies concerned with health care are required. Physicians have key roles in this regard. This group of health care workers can interact with other community sectors and spread the message of prevention at various levels (Table IV). However, as always, the need for prevention should come from within the population. a large number of social issues that are determinants of health behaviour must be considered. These are high levels of illiteracy, nuclear family structure, breakdown of traditional family system, improper peer influence and guidance, caste system, social hierarchy, lack of media awareness and unwillingness to change. Increasing levels of affluence and acculturation leads to greater recognition that preventive measures of chronic diseases are useful and cost-effective.

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Rajeev Gupta, Prakash C. Deedwania*, M.R. Soangra** Deptt. of Medicine, Monilek Hospital & Research Centre, Jaipur *Deptt. of Medicine, University of California-San Francisco School of Medicine, California USA **Deptt. of P.S.M., Government Medical College, Kota

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