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Helping you to practice evidence-based medicine

Estimating CVD risk and treatment benefit

Adapted from the New Zealand guidelines on management of dyslipidaemia[1] and raised blood pressure[2] by Rod Jackson

The charts help the estimation of a person's absolute risk of a cardiovascular event and the likely benefit of drug treatment to lower cholesterol or blood pressure. For these charts, cardiovascular events include: myocardial infarction, new angina, ischaemic stroke, transient ischaemic attack (TIA), peripheral vascular disease, congestive heart failure, and cardiovascular-related death.

There is a group of patients in whom risk can be assumed to be high (>20% in 5 years) without using the charts. They include those with symptomatic cardiovascular disease (angina, myocardial infarction, congestive heart failure, stroke, TIA, and peripheral vascular disease), or left ventricular hypertrophy on ECG.

To estimate a person’s absolute 5 year risk, select the table relating to their sex, diabetic status (on insulin, oral hypoglycaemics, or fasting blood glucose over 8 mmol/L), smoking status, and age.

Find the cell nearest to the person's blood pressure and total cholesterol : HDL ratio. For risk assessment it it enough to use a mean pressure based on two readings on each of two occassions, and cholesterol measurements based on one laborartory or two non-fasting Reflotron measurements. More readings are needed to establish the pre-treatment baseline. When the systolic and diastolic values fall in different risk levels, the higher category applies. The age shown in the charts is the mean for that category. i.e. age 60 = 55 to 65 years.

Roll over the colour boxes in the table to see the patients' level of five year cardiovascular disease risk and benefits of intervention.

References

  1. Dyslipidaemia Advisory Group. 1996 National Heart Foundation clinical guidelines for the assessment and management of dyslipidaemia. NZ Med J 1996;109:224–232.
  2. National Health Committee. Guidelines for the management of mildly raised blood pressure in New Zealand: Ministry of Health National Health Committee Report, Wellington, 1995.