Epidemiology

EPIDEMIOLOGY OF CORONARY HEART DISEASES (CHDs)

Dr Faris Al-Lami MB ChB MSc PhD FFPH

Salient Epidemiological Observations

Large population differences in CHD incidence and mortality rates Strong correlation between population differences in CHD rate and population differences in mean level and distribution of RFs especially lipids. Within population, a strong and continuous correlation between several RFs (S.Ch, BP, Smoking) and future risk of CHD

Salient Epidemiological Observations

Tracking of CHD RFs among children into adulthood Incidence and RFs of CHD in migrants rapidly approached level of adopted population Trends in CHD mortality rate , case fatality rate, and incidence occur over very short period (5-10 years)

Salient Epidemiological Observations

The decline in CHD mortality rate seen in industrial countries include all ages, both sexes, and all races The above decline is associated with decline in death rate , from stroke, all CVDs, and non-CVDs

Salient Epidemiological Observations

RCTs found direct effect of decrease in RFs on subsequent disease rate. Prospective studies found that established RFs and associated health behavior can be safely modified Epidemiological evidences are consistent with clinical and laboratory findings about causes and mechanism of atherosclerosis , which underlies the manifestation of CHDs

Risk Factors of CHDsDyslipidemia

Hypercholesterolemia is the most specific and the most essential factor There is a strong correlation between amount and duration of lowering S.Ch with decreased risk of CHD Lowering S.Ch is not associated with increase in mortality from non-CHDs

Dyslipidemia

LDL-C is a major component of T.Ch, and positively associated with CHD risk. It is affected by changes in diet and weight HDL-C is negatively associated with CHD risk. It is affected by exercise, weight, and smoking. It is higher in women The role of TG is less consistent. It is positively associated with T.Ch, and negatively with HDL-C level.

Hypertension

It is a strong RF especially in populations with high prevalence of CHDs SBP is better predictor of CHD events than DBP Life-style measures are more effective than mass medication in management of mild HT

Cigarette Smoking

RR is about 2 , higher in young and in population with high prevalence of CHD Cessation of smoking is important in primary and secondary prevention of CHDs Positive association between CHD risk and amount of smoking Passive smoking also increases CHD risk The risk is mediated mainly through increased plasma fibrinogen

Smoking Cessation Measures

Effective Measures: Social pressure Prohibition of smoking in public places and work Restricted advertisement Heavily taxed cigarette trade.

Smoking Cessation Measures

Ineffective Measures Personal advice Smoking cessation clinic Nicotine withdrawal therapy

Diabetes Mellitus

Diabetics have a very high risk which is equal in men and women It removes the relative protection of premenapausal women Insulin resistance is associated with HTG, low HDL-C, and high BP

Obesity

It increases risk of CHD, stroke, and other CVDs It is associated with DM, HT, high TG, high TCh, and low HDL-C Central obesity is particularly more dangerous

Physical Inactivity

CHD epidemic is associated with decreased physical activity at work and home Physical activity is difficult to be measured Exercise can decrease BP, weight , and improves lipid profile Even light exercise as walking is beneficial

Other Risk Factors :

Male Sex: CHD are 2 times more frequent in males Positive family history: aggregation of CRFs or increased susceptibility to a particular RF Dietary factors: the amount of fat, saturated fat, and cholesterol in the diet increases CHD risk. High consumption of fish and plant food offer protection

Other Risk Factors :

Natural antioxidants: lipid soluble (vitamin E, B-carotene) and water soluble (vitamin C, flavonides) decreases CHD risk Haemostatic factors: Hyperfibriniginemia High coagulation factor VII Impaired fibrinolytic activity High PAI-1



Other Risk Factors :
Oral Contraceptives: through: Increases body weight, BP and PAI-1 Decreases HDL-C level Altering blood coagulability , platelet function, fibrinolytic activity, and integrity of vascular endotheliumAlcohol intake: takes J –shape curve with CHD risk

Other Risk Factors :

Stress and type A personality: Increased sympathetic activity lead to increase catecholamine release, which will increase BP, PR, FFA, increases myocardial O2 demand, deceases O2 supply and alter platelet function Socioeconomic status: In developed countries, the association is inverse In developing countries the association is positive Job characteristics: perceived job stress, role ambiguity, job change, unemployment, and retirement

Other Risk Factors

Hyperuricemia: not established Hyperhomocystenemia: easily corrected by folic acid Hypercalcemia Role of trace elements: exposure to antimony, cobalt, and lead

Other Risk Factors

Inhalant occupational exposure: carbon disulphide, glyceryl nitric esters Water hardness: negative association with CHD risk Antiphospholipid antibodies: anticardiolipin, and anticephalothin antibodies Infection: Chlamydial pneumonia, dental infection, severe viral illnesses

Manifestations of CHDsAngina Pectoris

A major cause of disability from 4th decade onward Subjective diagnosis, with no gold standard: Rose questionnaire, : low sensitivity , specificity, and positive predictive value Resting ECG: not sensitive Ambulatory and exercise ECG : expensive Radioisotope scan: not practical Coronary angiography: not practical

Angina Pectoris

The more severe and persistent symptoms, the greater the risk of major coronary events The greater the number of indicators of myocardial ischemia, the more advanced the disease and the worse prognosis Various treatment procedures are palliative rather than curative


Myocardial Infarction
50% of MI cases are either atypical, missed, or misdiagnosed as seen by ECG surveys looking for Q or QS waves The following factors were found to improve survival: Prevention of VF early in the attack Initial treatment with aspirin or thrombolytic agents Long-term treatment with aspirin, B-blockers, and ACE inhibiters Avoidance of smoking Rehabilitation programs Cholesterol lowering treatment

Sudden Death

Definitions are variable from instantaneous death to death within 5 minutes, 1 hour, 3 hour, 12 hour, 24 hour. 70% of coronary deaths occurred outside the hospital. This led to: Development of mobile CCU Para-medical services Population training programs in resuscitation

Sudden Death

20-40% of potential coronary deaths had no history, symptoms, or autopsy findings of any diagnosis Autopsy studies found that sudden death could also be due to pneumonia, valvular heart disease, or alcohol overdose 50% of all deaths occurring within 28 days of severe chest pain occur within 2 hours of onset and mostly within very few minutes

Chronic Heart Failure

It accounts for small proportion of deaths, but increasing Its prevalence is increasing because of increase aging and increase in survival from CHD It follows history of MI or myocardial ischemia at many occasions

Chronic Heart Failure

Admission for HF increases with increased age, increased number of admissions for other coronary events and with DM It is a significant contributor to hospital cost ACE inhibiters are beneficial in increasing survival

Inter-relationship of various CHD manifestations

One type of CHD increases risk of other manifestations 20% of CHD victims have sudden death as a first manifestation More than 50% of coronary deaths and MI have history of AP or MI MI may terminate or initiate AP Myocardial ischemia on exercise test after MI indicate high risk of death or re-infarction



Women have lower rates of sudden death and MI than men, but have almost similar rates of AP Women have lower rates of CHD mortality than men A PARADOX: those admitted for coronary emergency without previous history have worse prognosis than those who have positive history

Prevention of CHDsPrimordial Prevention

1. National policies and programs on food and nutrition 2. Comprehensive policies to discourage smoking 3. Programs for prevention of HT 4. Programs to promote regular physical activity

Specific actions1. Tobacco control

Political commitment and support Special emphasis on the control among women, children, and adolescents. Effective health education Legislations and implementation of these legislations Role model by health professionals and school teachers Strengthening of cultural and religious values against smoking

Examples of Legislations

Banning smoking in public places, schools, and health care facilities Banning vending machines and selling cigarettes to children Banning of tobacco advertisement and promotion Preventing new investment in the development of tobacco industry Increasing taxation on tobacco product Appropriate warning labels

2. Physical Activity

Activities should be feasible and able to be incorporated into daily life Encouraging sports activities at schools and workplace Formulation and use of guidelines on physical exercises Changing the misconception of both women and community about obesity through health education

3. Nutrition and dietary modification

It should cover all aspects of food chain from production to consumption Multi-sectoral collaboration is essential (agricultural, trade, industry, education, health) Health education and specific legislations are basic components

Dietary Guidelines

A balanced intake of calories A reduced salt content of the diet A reduced total saturated fat intake A rise in the consumption of fruits and vegetables Prevention of unhealthy dietary habits and stopping the cultural invasion of fast food It is necessary to strengthen the role of the school health curriculum which should cover the knowledge and attitudes needed for CVD prevention

The Regional Situation

In the WHO Region for the Eastern Mediterranean, Chronic Diseases (CVD, Cancer, Diabetes etc..) account for 52% of all deaths and 47% of the disease burden in EMR during the year 2005 This burden is likely to rise to 60% in the year 2020. The conventional risk factors may explain 75% of chronic diseases.

Cardiovascular

Chronic Respiratory Disease
Type 2 Diabetes
Cancer
Chronic Diseases result in percent of deaths
4
52
EMR Adult Population

EMR/NCD RISK FACTORS

Smoking 16-65% Hypertension 12-35% Diabetes 7-25% Over weight-obesity 40-70% Dyslipidemia 30-70% Physical Inactivity 80-90%

Stepwise data from some EM countries

Country
Year of field work
DM %
HT %
Overweight & Obesity %
Iraq
2006
10.4
40.4
66.9
Jordan
2007
16
25.5
67.4
Saudi Arabia
2005
17.9
26
Syrian Arab Republic
2003
19.8
28.8
56.3
Kuwait
2005
16.7
24.6
81.2
Egypt
2005
16.5
33.4
76.4
Sudan
2005
19.2
23.6
53.9

Stepwise data from some EM countries

Country
Year of field work
Hyper-cholestrolemia %
Smoking %
Low physical activity %
Low intake of fresh fruit & vegetables %
Iraq
2006
37.5
21.6
56.7
92.3
Jordan
2007
26.2
29
5.2
14.2
Saudi Arabia
2005
19.3
12.9
33.8
91.6
Syrian Arab Republic
2003
33.5
24.7
32.9
95.7
Kuwait
2005
42
15.7
91.5
89
Egypt
2005
24.2
21.8
50.4
79
Sudan
2005
19.8
12
86.8
1.7/day

Prevalence of Smoking according to STEPwise Survey in EM countries

%