The National Vascular Disease Prevention Alliance claims there is a low level of understanding and use of absolute risk tools by GPs. A 2008 study showed a nominal uptake of 60%, but when patients were classified as at ‘high risk’, the usefulness of the charts was often discounted, and about two-thirds of these patients were not prescribed medication to lower their blood pressure and cholesterol.
Current GP guidelines recommend the absolute risk approach to CVD and in 2009 the Heart Foundation carried out extensive GP education.
Understanding your risk factors
Risk factors of age, sex, family history of premature CVD, ethnicity and social status are outside your control. Family history means a first-degree relative (parent or sibling) has had a stroke or a heart attack, before 55 for men and 65 for women.
Factors you can influence are high blood pressure, elevated cholesterol and blood fats (lipids), smoking, physical inactivity, overweight/obesity, diabetes, excessive use of alcohol, and stress.
BP should be recorded for adults aged 18 to 50 every two years, provided systolic (heart pumping) pressure remains less than 120 and diastolic (heart relaxing) pressure remains less than 80. If your BP is higher than that, you need more frequent checking. Gone forever are the days when an estimate of ‘normal’ systolic BP came from adding your age in years to 100. Easy-to-use home BP monitoring devices are reasonably accurate and readily available from pharmacies for less than $100.
Cholesterol levels in the blood are affected by diet, genetics and exercise. Saturated animal fats and some cooking oils (palm oil used by some fast food chains) are major contributors to cholesterol build-up. How individuals handle dietary fats depends on their genetics, and the results of lifestyle changes on cholesterol levels can be disappointing. Adopting the NHMRC Dietary Guidelines for Australian Adults, exercising vigorously and frequently, and maintaining a healthy weight will only reduce cholesterol by up to 30%. Some very effective prescription medicines, such as statins, lower blood lipids.
When your GP requests a blood lipid test from a laboratory, your results and a ‘normal’ range (which may differ slightly between laboratories) are both provided. These ‘normal ranges’ were those used by the SA Institute of Medical and Veterinary Science in 2009:
Total triglycerides 0.3-2.0 mmol/L
Total cholesterol < 5.5
High Density Lipoprotein (HDL) 0.9-2.0
Low Density Lipoprotein (LDL) < 3.7
Total cholesterol/HDL ratio < 5.0
(The National Heart Foundation, in 2001, recommended a total cholesterol of < 4mmol/L.)
To find your CVD risk, the chart requires your total cholesterol-to-HDL ratio (total cholesterol divided by HDL). HDL is the ‘good’ cholesterol, since it reduces CVD risk. LDL is the ‘bad’ cholesterol as it lays down fat in blood vessel walls. The lower your LDL levels are the better.
Overweight can be assessed using BMI, waist circumference and waist-to-hip ratio (WHR). The build-up of body fat in and around the abdomen, rather than on your thighs and buttocks, may be a better predictor of future CVD than BMI, so waist circumference or WHR may be more accurate indicators.
The August 2006 edition of the American Journal of Clinical Nutrition asserts that if WHR was to be used instead of BMI, the number of people considered to be at risk of CVD would triple. The WHR figures below are adapted from that journal.
CVD Risk Men Women
Low risk <0.96 <0.81
Moderate risk 0.96 – 1.0 0.81 – 0.85
High risk >1.0 >0.85