How to assess absolute cardiovascular risk

There are 3.5 million Australians with cardiovascular disease (CVD).1 It accounts for 11% of Australia’s healthcare expenditure, and is responsible for more deaths than any other disease. With an aging population this burden is expected to increase.2

There are multiple lifestyle risk factors that contribute to a person developing CVD, and around half of all Australian’s have more than 2 factors.3 Lipid abnormalities, smoking, hypertension, diabetes, abdominal obesity, psychosocial factors, physical inactivity and poor diet contribute around 90% of the risk for myocardial infarction.2,4

Why assess absolute CVD risk?

Assessing multiple risk factors in your patient is more accurate than assessing single risk factors.2 This is because clusters of risk factors can develop that may be additive or synergistic.2 Assessing and addressing multiple factors may be more effective than concentrating on a single risk factor.2,5

For example, if your patient has a BMI of >30, smokes daily and has a BP of 152/95 mm Hg, only addressing the hypertension will still leave that person at increased risk of CVD because of the risk associated with obesity and smoking.

When and who to assess

The National Vascular Disease Prevention Alliance guidelines advise that absolute CVD risk is calculated in all adults aged 45–74 years who are not known to have CVD, or already known to be at high risk of CVD. Perform CVD absolute risk assessment from 35 years in Aboriginal and Torres Strait Islander peoples.

People who do not need formal absolute CVD risk calculations because they are already at a high risk of CVD are those with:

  • history of cardiovascular events or known CVD
  • diabetes and age > 60 years
  • diabetes with microalbuminuria (>20 micrograms/min or urinary albumin:creatinine ratio >2.5 mg/mmol for males, > 3.5 mg/mmol for females)
  • moderate or severe chronic kidney disease
  • previous diagnosis of familial hypercholesterolaemia
  • systolic BP ≥180 mm Hg; diastolic BP ≥ 110 mm Hg
  • serum total cholesterol >7.5 mmol/L

What is involved in absolute CVD risk calculation?

Assess risk factors

Modifiable risk factors Non-modifiable risk factors Related conditions
Smoking status
Blood pressure
Serum lipids
Waist circumference and body mass index (BMI)
Nutrition
Physical activity level
Alcohol intake
Age and sex
Family history of CVD
Social history, including mental health, cultural identity, ethnicity, socioeconomic status

Diabetes
Kidney function
Familial hypercholesterolaemia
Evidence of atrial fibrillation

Assess fasting blood lipids6

Assess:

  • fasting total cholesterol,
  • low-density lipoprotein cholesterol (LDL)
  • high-density lipoprotein cholesterol(HDL)
  • triglycerides.

If lipid levels are abnormal a secondary confirmation should performed on a separate occasion.

Measure blood pressure6

According to the RACGP red book, measure blood pressure on two separate occasions with a calibrated mercury sphygmomanometer or automated device that is regularly calibrated. Measure BP in both arms at the first assessment, then in the arm measuring the highest at subsequent assessments.

Calculating absolute CVD risk

Calculate absolute CVD risk an easy to use tool to calculate the 5-year absolute risk.

You will be asked to enter the following information about the patient:

  • sex
  • age
  • systolic blood pressure
  • smoking status
  • total cholesterol
  • HDL-cholesterol
  • diabetes
  • presence of left ventricular hypertrophy.

The tool will calculate a person's 5-year risk of developing CVD.

RACGP interventions vary based on level of risk

For more detailed information about interventions recommended following an absolute cardiovascular risk assessment see the RACGP red book.

Risk level2 Intervention2,6 Follow-up period6
Low risk < 10% probability of CVD within the next 5 years
Provide lifestyle advice
Offer antihypertensives if BP is persistently above 160/100 mm Hg
Repeat fasting lipids every 5 years
Moderate risk 10–15% risk of CVD within 5 years
Provide intensive lifestyle advice
Consider antihypertensives and/or cholesterol-lowering therapies if not reaching target reduction in risk after 6 months of lifestyle intervention or in people with a family history of CVD or in Aboriginal and Torres Strait Islander peoples or people with NZ Maori, Pacific islander, South Asian, Middle eastern descent.
Offer antihypertensives if BP is persistently above 160/100 mm Hg
Repeat fasting lipids every 2 years
High risk > 15% risk of CVD within 5 years Provide intensive lifestyle advice
Start cholesterol-lowering therapy simultaneously with antihypertensives (unless contraindicated)
Review every 12 months

For more information

References
  1. Australian Institute of Health and Welfare. Cardiovascular Disease, 2011
  2. National Vascular Disease Prevention Alliance. Guidelines for the assessment of absolute cardiovascular disease risk. 2009. www.cvdcheck.org.au/ (accessed 9 March 2013).
  3. Australian Institute of Health and Welfare. Risk factors contributing to chronic disease. 2012. www.aihw.gov.au/publication-detail/?id=10737421466 (accessed 13 February 2013).
  4. Yusuf S, Hawken S, Ounpuu S, et al. Effect of potentially modifiable risk factors associated with myocardial infarction in 52 countries (the INTERHEART study): case-control study. Lancet 2004;364:937–52. [PubMed]
  5. Jackson R, Lawes CM, Bennett DA, et al. Treatment with drugs to lower blood pressure and blood cholesterol based on an individual's absolute cardiovascular risk. Lancet 2005;365:434–41. [PubMed]
  6. The Royal Australian College of General Practitioners. Guidelines for preventive activities in general practice (The Red Book) 8th Edition. Melbourne: RACGP, 2012. http://www.racgp.org.au/your-practice/guidelines/redbook (accessed 11 February 2013).