Epidemeology of CVD Flashcards
Describe coronary heart disease pathology
The heart needs a constant supply of oxygen to produce the enormous amount of work it perfoms. The heart is basically a muscle that works as a pump.
Coronary arteries are the main vessels carrying blood to the muscle.
If you interrupt this flow for a certain amount of time, the muscle will die, and the function of the heart as a pump will be compromised.
The main process responsible for decreasing blood supply is the blocking of coronary arteries.
A complex phenomenon called atherosclerosis starts to form a plaque, composed mainly of lipids. While the factors leading to plaque formation are present, the plaque will grow and progressively obstruct a larger proportion of the vessel lumen, decreasing blood flow. When a critical limit is reached (around 75% of the lumen), symptoms begin, mainly oppresive chest pain, that we called angina. However more dramatic events may occur, and suddenly, the plaque may rupture and triggers the formation of a clot, that occludes totally the artery. If not reopen, the portion of myocardium supplied by that artery will die, causing an infarct. Depending on the size and other phenomena, the patient may die suddenly or suffer a heart attack, we call it an acute myocardial infarction.
Describe the natural history of a CHD patient- what’s the typical pattern of disease progression?
Let’s put this events into the perspective of a lifetime.
These process starts early in adulthood, as autopsies in young people has shown, and progress mainly asymptomatic for a long time, until the critical stage is reached, starting the symptoms or suddenly, the development of inflamatory process and thrombosis cause a total occlusion of the vessel .These dramatic events may present as sudden death or by excruciating chest pain signaling a myocardial infarction.
If you survive the heart attack, the loss of muscle in the heart decrease its ability to work as a pump, leading to heart failure.
Clinical presentations of CHD
SUDDEN CARDIAC DEATH
HEART ATTACK /myocardial infarction/MI
ANGINA (chest pain on exertion or stress)
progressive HEART FAILURE (shortness of breath, ankle oedema & fatigue)
Many patients chronically disabled with POOR QUALITY OF LIFE
So, atherosclerosis in the coronary artery may present in several ways:
Sudden death, a myocardial infarction, chronic chest pain or heart failure
But what is more important is that These clinical features of coronary heart disease increases dramatically your chances of dying and substantially affect your quality of life.
Why is CHD a big issue? use stats
70,000 deaths UK annually, 23,000 premature (<75 years)
16% of all male and 10% female deaths
2.3 million living with CHD
relatively high mortality rates internationally
2.5 million years of life lost annually
£6.8 billion costs NHS costs
Costly problem for nhs too:
200,000 Myocardial Infarctions (MIs) per year
30,000 out of hospital cardiac arrests (survival <1 in 10)
Almost 1 million have survived a heart attack
CHD PREVALENCE ~ affects 2.3 million people in UK
(about 1/3 middle-aged & elderly people)
NHS ACTIVITY ANNUALLY (approximate figures)
GPs see 1million individuals
Hospitals admit half a million CHD patients
3.5% NHS admissions UK men, 1.5% UK women
97,000 get angioplasty, & 16,000 CABG
Describe CHD epidemeology
Depends on the time, place and person
Traditionally, we try to understand a disease by describing its epidemiology, and we mainly do this by describing its distribution in terms of place, time and person
Despite recent improvement, the death rate from CHD in the UK is amongst the highest in the world. In countries of Eastern and Central Europe - where death rates have been rising rapidly recently - the death rates are generally higher than in the UK, but amongst developed countries only Ireland and Finland have a higher rate than the UK .
While the death rate from CHD has been falling in the UK it has not been falling as fast as in some other countries. For example, the death rate for men aged 35-74 fell by 37% between 1986 and 1996 in the UK, but it fell by 45% in Denmark and Norway and by 43% in Australia. For women the death rate fell by 36% in the UK but in Australia, Finland and New Zealand the rate fell by 49%, 44% and 44% respectively.
What is a risk factor?
ANY characteristic which IDENTIFIES a group at increased (decreased) risk of disease
They need NOT be:-
- independent - causal - modifiable
Classic example is AGE
What is a cause
A CAUSE is a factor which itself increases risk of disease (prevalence, incidence, mortality)
Cause = a biological, not a sociocultural
phenomenon
What are the types of prevention
PRIMARY PREVENTION (before disease presents)SECONDARY PREVENTION (reduce complications) TERTIARY PREVENTION (rehabilitation)
As you probably known, we use these terms when talking about controlling non communicable diseases. When we want to tackle disease before it presents, we call these interventions as primary prevention, when the disease is present, we try to reduce the chance of death, progression and complications, and we call this secondary prevention, and when we mainly try to improve function and quality of life of people with disease, we used the term tertiary prevention
Methods for preventing coronary heart disease
- Prevention in people who already have CHD (secondary prevention)
- Prevention in people who are free from CHD (primary prevention)
What is the available evidence for CHD treatments?
We have a really large evidence base to decide on the effectiveness of these treatments. For every item in this list we can found a large systematic review with thousands of patients on which base our decisions.
They are effective, but they are costly. And we know that they have a role when the disease is already present, and we will be less succesfull in postponing death at this stage.
But we are putting a lot of money on them, and for some people, seems to be our only weapons against the disease.
So a pertinent question is: Which is best? Primary prevention or secondary prevention?
2 ways of pPrevention in people who already have CHD (secondary prevention)
-Prevention in people who are free from CHD (primary prevention)
How do we prevent CHD in people who do not already have it?
How should we prevent CHD in people who do not yet have it?
IDENTIFY REDUCE
HIGH RISK RISK IN
SUBJECTS POPULATION
Categorise patient by key risk factors e.g. sex, age, diabetes status, smoker, BP and cholesterol Risk of major CV event within 10 years
QRISK2 score used to identify subjects with 10 year CVD risk of 10% or more
- age and sex
- ethnicity
- deprivation
- systolic BP
- BMI
- BP treatment
- ratio total : HDL cholesterol
- cigarette smoking
- CKD / RA / AF
- diabetes
CVD causal pathways
Upstream” “Downstream”
determinants causes
Food Salt Blood Pressure
Food Sat Fats Cholesterol
Food Trans Fats Cholesterol
NICE guidance for CHD prevention
Evidence base surprisingly strong:
meta-analyses & natural experiments
Potentially big disease reductions
COST SAVING, RAPID, EQUITABLE, ACCEPTABLE
Challenges in controlling CHD?
We know the major factors which cause CHD in practice
Need to understand reasons for social and ethnic differences
Implementing prevention in clinical practice
Implementing population-based strategies for reducing CHD risk
Controlling epidemic in developing world
Summary
CVD: long asymptomatic phase followed by a shorter clinical phase
Opportunities for prevention
Main determinants of CHD are known
Trends declining in developed countries
Delaying or preventing deaths by early interventions on CHD determinants
Debate about individual and population approaches to prevention
Large evidence based for treatments
Relative contributions of CVD prevention
primary > secondary > tertiary
