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Testing Protocols - JBS Cardiac Risk

Introduction

The programme is for estimating cardiovascular disease (CVD) risk (non-fatal myocardial infarction, stroke and TIA, coronary and stroke death and new angina pectoris) for individuals who have not already developed coronary heart disease or other major atherosclerotic disease. It is an aid to making clinical decisions about how intensively to intervene on lifestyle and whether to use antihypertensive, lipid lowering and anti-platelet medication, but should not replace clinical judgment. The programme is primarily to assist in directing intervention for those who typically stand to benefit most, but there may be others who in the view of the clinician should also be considered for intervention. The use of the programme is not appropriate for people who have existing diseases or are at higher risk for other medical reasons.

Examples are:

1. Coronary heart disease or other major atherosclerotic disease
2. Familial hypercholesterolaemia or other inherited dyslipidaemias
3. Renal dysfunction
4. Type 1 and 2 diabetes mellitus

The programme should not be used to decide whether to introduce antihypertensive medication when blood pressure is persistently at or above 160/100 or when target organ damage due to hypertension is present.In both cases antihypertensive medication is recommended regardless of CVD risk. Similarly the programme should not be used to decide whether to introduce lipid-lowering medication when the ratio of serum total to HDL cholesterol exceeds 6. Such medication is generally then indicated regardless of estimated CVD risk.

User Guide

To estimate absolute CVD risk for primary prevention, please ensure you have the following data available.

1. Gender
2. Total serum cholesterol - mmol/l
3. Age - years
4. HDL cholesterol - mmol/l
5. Diabetic Status - Yes/No
6. SBP - mmHg
7. DBP - mmHg
8. Smoking status - number of cigarettes per day

You also have the option of entering the following additional data in which case the programme may give you additional information including a higher estimate of absolute CVD risk:

• Fasting glucose - mmol/l
• South Asian origin - Yes/No
• Adverse family history - Yes/No
• Fasting triglyceride - mmol/l
• Left ventricular hypertrophy - Yes/No

South Asian origin means descended from inhabitants of the Indian subcontinent. Adverse family history means CHD, stroke or other major atherosclerotic disease in a male first degree relative before the age of 55 years or in a female first degree relative before the age of 65 years. Left ventricular hypertrophy (LVH) can be ascertained from a resting ECG or by echocardiography. All concentrations must be in mmol/l

View the Fitech JBS Report here

Absolute Risk

Higher risk individuals are defined as those whose 10 year CVD risk exceeds 20%, which is approximately equivalent to the coronary heart disease risk of >15% over the same period.The programme also assists in the identification of individuals whose 10 year CVD risk moderately increased in the range 10-20% and those in whom risk is lower than 10% over 10 years.From age 70 years, the CVD risk, especially for men, is usually (20% over 10 years. The programme will thus refuse to calculate risk in people aged 70 years or more. It will also refuse to calculate risk in those 35 years or less. Some patients with inherited dyslipidaemia, hypertension or diabetes may require treatment before then on clinical grounds (see JBS recommendations).

If diabetes is entered the programme will refuse to calculate risk. If a fasting blood glucose is available, its value can be entered. Should this be 7mmol/l or greater, the programme will refuse to calculate risk because the patient is likely to have diabetes. If the value is between 6.1 and 6.9mmol/l, the patient has impaired fasting glucose and the programme will adjust risk upwards to account for this. In addition to fasting glucose, other additional risk factors which may be optionally entered are fasting triglyceride concentration, South Asian origin, adverse family history (CVD in a male first degree relative aged <55 years or a female first degree relative aged <65 years) and left ventricular hypertrophy (on ECG or echocardiogram).

The programme will adjust risk upwards for whichever of these has the most impact. 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 programme. The initial blood pressure 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.

This programme (and all currently available methods of CVD risk prediction) are based on groups of people with untreated levels of blood pressure, total cholesterol and HDL cholesterol. In people already receiving antihypertensive therapy in whom the decision is to be made about whether to introduce lipid-lowering medication, or vice versa, the programme can only act as a guide. 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 blood pressure or lipids on treatment.

Read the BMJ article on: JBS 2: Joint British Societies' guidelines on prevention of cardiovascular disease in clinical practice