CLINICIANS are being urged to embrace an absolute risk approach to cardiovascular disease prevention, with a leading primary care expert saying the term “hypertension” had reached its use-by date.
Writing in the MJA, Professor Mark Nelson, Chair of the Discipline of General Practice at the University of Tasmania, said that more widely adopting the absolute cardiovascular risk approach would better target pharmacotherapy.
“Such an approach recognises that drug therapy should be considered in the context of the whole person, while acknowledging that action on risk stratification can be challenging and complex for many,” Professor Nelson wrote.
Speaking to MJA InSight, Professor Nelson said that adopting an absolute risk approach enabled more appropriate treatment for two major patient groups.
“If you move from hypertension to absolute risk, there are two major groups who are reclassified. They are the so-called low risk hypertensive individuals, people whose blood pressure is above 140, but their absolute risk is low [so they don’t require treatment]. That tends to be younger people who, in the past, were stuck on decades of medication.
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“The other group is the so-called normotensive group who are at high risk,” he said, adding that last year’s Systolic Blood Pressure Intervention Trial showed that these patients could still benefit from treatment to lower their blood pressure.
Professor Nelson said that looking at the absolute cardiovascular risk liberated clinicians from the constraints of blood pressure thresholds and targets.
“GPs who are concerned about side effects [of blood pressure lowering therapy] in the elderly don’t have to continue to push them from 180 all the way down to 120,” he said. “If the maximum tolerable low-dose combination of three medications reduces them from 180 to 140, that’s fine. It’s the magnitude of the lowering of the blood pressure that’s important and less about where the level is.”
Professor Nelson’s paper was published after the release last week of the National Heart Foundation’s updated guideline on hypertension management. The guideline was criticised by the Royal Australian College of General Practitioners for being inconsistent with the National Vascular Disease Prevention Alliance’s absolute cardiovascular risk guidelines, which have been endorsed by the National Health and Medical Research Council.
Professor Nelson, who noted that his paper was submitted to the MJA before the release of the updated guideline, said he would have liked the guideline committee to have abandoned the term “hypertension”.
“The term hypertension – which is not well understood by patients – has outlived its usefulness,” Professor Nelson told MJA InSight. “We need to start thinking about elevated blood pressure again.”
Professor Nelson said that while clinicians may like the term, it perpetuated the idea that hypertension was a disease, not a risk factor.
Emily Banks, Professor of Epidemiology and Public Health at the Australian National University, said increasing the use of absolute risk to guide treatment decisions would build upon the successes already achieved in cardiovascular disease, with an 80% drop in cardiovascular death rates since 1968.
“We have had such a triumph over cardiovascular disease and primary care has been in the front line of that success,” she said.
“But it’s still the single leading cause of death, so there’s a long way to go, and an absolute risk approach is going to be a really important part of continuing that success.”
Research conducted by Professor Banks and colleagues earlier this year found that around 20% of the Australian population aged 45–74 years were at high absolute cardiovascular risk – 9% had had a cardiovascular event and 11% were found to be high risk of their first event according to the absolute cardiovascular risk calculator assessment.
“We also found that most of those people at high risk were not receiving blood pressure and lipid-lowering medication,” she said. “Around 44% of those who had already had a cardiovascular disease event were getting treated, and only around 24% of those who were at high primary risk level were receiving both those treatments.”
Professor Banks said many GPs continued to rely on a single risk factor approach, which both under- and over-estimated cardiovascular risk.
“This leads to the dual problem of treating people at low absolute risk inappropriately, and missing substantial numbers of people who are at high absolute risk for whom treatment is recommended,” she said.
“Using the absolute risk approach not only targets treatment appropriately, it is also a better use of resources.”
Professor Banks also noted that patient adherence to therapy was an issue that needed to be addressed, because many high risk patients were essentially well and needed to understand that the goal of long-term therapy was to prevent a future cardiovascular event.
Professor Clara Chow, Director of the Cardiovascular Division of the George Institute for Global Health, agreed that focusing on absolute cardiovascular risk offered the “best bang for our buck” in ensuring that treatment was well targeted.
“We want the blood pressure much lower in a patient with high vascular risk, whereas in a patient who hasn’t got high vascular risk, then it’s okay for their blood pressure to be a bit higher,” she said.
She said clinicians had long struggled with defining an appropriate cut-off point for hypertension.
“It is important to stand back and say ‘what is the overall risk of a cardiovascular event in a patient?’ and treat that with blood pressure-lowering therapy as opposed to worrying about whether they have hypertension by the current definition or not,” said Professor Chow, who is also Professor in the Faculty of Medicine at the University of Sydney.
Professor Nelson said Australian clinicians had been slow to adopt the absolute cardiovascular risk factor approach. But, he said, moves to align the Pharmaceutical Benefits Scheme criteria for statins with absolute cardiovascular risk guidelines could help to familiarise GPs with the concept, which could lead to broader use.