The Framingham risk equation is out, and an increased number of risk factors, including socio economic status, are in

The Heart Foundation has released new guidelines for assessing and managing cardiovascular risk, along with an updated risk calculator that it says is better targeted and more predictive than its predecessor.

“Now we have a more accurate risk prediction equation that is better suited for our Australian population,” says Natalie Raffoul, Healthcare Programs Manager at Heart Foundation, who has spent three years bringing this to fruition with her team. “It’s based on contemporary, more relevant data from New Zealand, and the equation itself has been modified and recalibrated for the Australian population.”

“2012 was the last guideline, with the Framingham risk equation based on 60-year-old data from a town in the US, and we were using that to predict risk in our population. Now it’s out there, we’ve got to get going with implementation,” says Heart Foundation healthcare programs manager Natalie Raffoul .

The previous Framingham-based equation had far fewer variables: gender, age, systolic blood pressure, total cholesterol, HDL cholesterol, smoking status, diabetes diagnosis and left ventricular hypertrophy. “They’re very simple, traditional risk factors,” Raffoul says, “and at the time it served its purpose, it was the best we had, but now we’re able to provide more granular risk assessment.”

For example, the retiring risk calculator asks merely if diabetes has been diagnosed. Raffoul explains that ticking yes would double the risk automatically, pushing many patients straight into the high-risk category. Although diabetes is indeed a risk factor for cardiovascular disease, we know that individual risk is much more nuanced. The new calculator allows further stratification based on the duration of diabetes, body mass index, glycaemic control, and the presence or absence of microvascular complications.

The new calculator also takes into account atrial fibrillation, use of cardiovascular medications, and socioeconomic status. “The fact that we have socioeconomic disadvantage, by way of post code, included in the equation is really important for us. It’s the first time we’ve been able to incorporate social deprivation in the assessment,” Raffoul says. The postcode assessment can be manually altered by the clinician in accordance with their knowledge of the patient.

The new calculator also includes reclassification factors. These include family history of premature CVD, personal history of severe mental illness (with severe meaning requiring specialist treatment), chronic kidney disease, ethnicity, and coronary calcium score.

“These variables are factors that we know contribute to cardiovascular risk, but we may not have the data to insert it into the algorithm itself,” says Raffoul. “This gives the clinician discretion to move the risk category up or down if the patient is close to the threshold.”

The new CVD risk categories are:

• High (≥10% risk of having a CVD event in the next 5 years)
• Intermediate (5 to <10% risk over 5 years)
• Low (<5% risk over 5 years).

It’s important to note that the new risk categories and percentages are not directly comparable to those of the old calculator. Raffoul explains that the >15% risk category from the Framingham-based equation is roughly equivalent to the ≥10% risk category in the new one.

The cut-offs for the new equation are based on a systematic review of when to start pharmacological treatment.

“We looked at the existing literature, compared risk equations across the world, and looked at the number needed to treat and number needed to harm in terms of starting medicines in those different categories.”

As a result, the expert advisory group recommends both lipid-lowering and blood pressure lowering for high risk individuals, and suggests that clinicians consider them for intermediate risk individuals.

This does not reflect a lowering of the treatment threshold, says Raffoul. Her take-away is not to focus on the specific numerical risk, but rather the risk category – low, intermediate or high –
which she says is now more accurate for the individual patient because it is based on more factors and better data.

The new guidelines have also expanded who to assess with the new calculator, now recommending it for anyone aged 45 to 79 without known CVD, and starting from 35 for people with diabetes and 30 for first nations people.

There’s also a section on communicating risk, and the calculator has patient decision-making support tools embedded into it. “Unless you’re explaining risk appropriately, and the patient is involved in that decision making, they’re not going to take action and it’s not going to make any difference,” Raffoul says.

GPs looking to start using the new calculator will need to access it via the website for now (www.cvdcheck.org.au/calculator) as the Heart Foundation is still working with software providers to have it integrated into clinical software. “That’s the first pressing issue for us,” says Raffoul. She assures us that the Department of Health has committed funding to implement the new guidelines, “and one of the priorities of that implementation is to work really closely with software providers to get it integrated.”