Proposed Joint British Societies Cardiovascular Disease Risk Prediction
Chart |
Cardiovascular Disease Risk Prediction Chart reproduced with permission from
The University of Manchester Department of Medical Illustration, Manchester
Infirmary
How to use the Cardiovascular Disease Risk Prediction Charts
for Primary Prevention These charts are for estimating
cardiovascular disease (CVD) risk (non-fatal myocardial infarction [MI] and
stroke, coronary and stroke death and new angina pectoris) for individuals who
have not already developed coronary heart disease (CHD) or other major
atherosclerotic disease. They are an aid to making clinical decisions about how
intensively to intervene on lifestyle and whether to use antihypertensive,
lipid lowering medication and aspirin.
- The use of these charts is not appropriate for the following patients groups.
Those with:
- CHD or other major atherosclerotic disease
- Familial hypercholesterolaemia or other inherited dyslipidaemias
- Chronic renal dysfunction
- Type 1 and 2 diabetes mellitus
- The charts should not be used to decide whether to introduce antihypertensive
medication when blood pressure (BP) is persistently at or above 160/100 or when
target organ damage (TOD) due to hypertension is present. In both cases
antihypertensive medication is recommended regardless of CVD risk. Similarly
the charts should not be used to decide whether to introduce lipid-lowering
medication when the ratio of serum total to high density lipoprotein (HDL)
cholesterol exceeds 7. Such medication is generally then indicated regardless
of estimated CVD risk.
- To estimate an individual's absolute 10 year risk of developing CVD choose the
table for his or her gender, smoking status (smoker/non-smoker) and age. Within
this square define the level of risk according to the point where the
coordinates for systolic blood pressure (SBP) and the ratio of total
cholesterol to HDL-cholesterol meet. If no HDL cholesterol result is available,
then assume this is 1.00mmol/l and the lipid scale can be used for total serum
cholesterol alone.
- Higher risk individuals (red areas) are defined as those whose 10 year CVD risk
exceeds 20%, which is approximately equivalent to the CHD risk of >15% over
the same period indicated by the previous version of these charts. As a minimum
those at highest CVD risk (greater than 30% shown by the line within the red
area) should be targeted and treated now. When resources allow, others with a
CVD risk of >20% should be progressively targeted.
- The chart also assists in the identification of individuals whose 10 year CVD
risk moderately increased in the range 10-20% (orange area) and those in whom
risk is lower than 10% over 10 years (green area).
- Smoking status should reflect lifetime exposure to tobacco and not simply
tobacco use at the time of assessment. For example, those who have given up
smoking within 5 years should be regarded as current smokers for the purposes
of the charts.
- The initial BP and the first random (non-fasting) total cholesterol and HDL
cholesterol can be used to estimate an individual's risk. However, the decision
on using drug therapy should generally be based on repeat risk factor
measurements over a period of time.
- Men and women do not reach the level of risk predicted by the charts for the
three age bands until they reach the ages 49, 59, and 69 years respectively.
Everyone aged 70 years and over should be considered at higher risk. The charts
will overestimate current risk most in the under forties. Clinical judgement
must be exercised in deciding on treatment in younger patients. However, it
should be recognised that BP and cholesterol tend to rise most and HDL
cholesterol to decline most in younger people already possessing adverse
levels. Thus untreated, their risk at the age 49 years is likely to be higher
than the projected risk shown on the age-less-than 50 years chart.
- These charts (and all other currently available methods of CVD risk prediction)
are based on groups of people with untreated levels of BP, total cholesterol
and HDL cholesterol. In patients already receiving antihypertensive therapy in
whom the decision is to be made about whether to introduce lipid-lowering
medication or vice versa the charts can act as a guide, but unless recent
pre-treatment risk factor values are available it is generally safest to assume
that CVD risk is higher than that predicted by current levels of BP or lipids
on treatment.
- CVD risk is also higher than indicated in the charts for:-
- Those with a family history of premature CVD or stroke (male first degree
relatives aged <55 years and female first degree relatives aged <65
years) which increases the risk by a factor of approximately 1.5
- Those with raised triglyceride levels
- Women with premature menopause
- Those who are not yet diabetic, but have impaired fasting glucose
(6.1-6.9mmol/l)
- In some ethnic minorities the risk charts underestimate CVD risk, because they
have not been validated in these populations. For example, in people
originating from the Indian subcontinent it is safest to assume that the CVD
risk is higher than predicted from the charts (1.5 times).
- The charts may be used to illustrate the direction of impact of risk factor
intervention on estimated level of CVD risk. However, such estimates are crude
and are not based on randomised trial evidence. Nevertheless, this approach
maybe helpful in motivating appropriate intervention. The charts are primarily
to assist in directing intervention to those who typically stand to benefit
most.
|
|
 |
|