Strategies for cardiovascular disease (CVD) prevention using lipid-lowering medications can be improved by adopting the absolute-risk approach, according to a research paper in the latest issue of the Medical Journal of Australia.
Lipid-lowering medication reduces blood cholesterol levels, an important risk factor for CVD. Under the absolute-risk approach, the decision to use this medication to treat people at risk of CVD depends on the estimated overall level of risk based on multiple independent risk factors rather than the level of any single risk factor such as cholesterol or blood pressure.
Professor Andrew Tonkin, head of the Cardiovascular Research Unit at Monash University, and his co-authors determined how well the current Pharmaceutical Benefits Scheme eligibility criteria for subsidy of lipid-lowering drugs compared with current national guidelines for determining who is at risk of developing CVD.
CVD accounted for more than 30 per cent of Australian deaths in 2005. The 2004/05 National Health Survey showed that 3.8 per cent of the Australian population had at least one of the four major manifestations of CVD: coronary heart disease, stroke, peripheral vascular disease or heart failure.
Dr Tonkin and his co-authors analysed data from the Australian Diabetes, Obesity and Lifestyle (AusDiab) study conducted in 1999-2000. The researchers used a multivariable risk prediction equation to calculate the five-year risk of developing first-time CVD in 8,286 participants who did not have diabetes (another important CVD risk factor) and were aged between 30 and 74 years.
The study found that 7.9 per cent of men and 1.5 per cent of women had at least a 15 per cent chance of developing CVD within five years and were considered as having high absolute risk.
"To our knowledge, this study is the first to describe population estimates of people with high CVD risk in a contemporary Australian population," Dr Tonkin said.
"Of the estimated residential Australian population in 2000 aged 30-74 years without CVD or diabetes, 717,000 people were considered to be at high absolute CVD risk … However, [based on projected estimates from the AusDiab participants] more than 80 per cent of people in this high-risk population were not being treated with lipid-lowering medication, indicating that current primary prevention of CVD is suboptimal.
"Our finding that 13 per cent of women and 44 per cent of men with neither CVD nor diabetes who were already being treated with lipid-lowering medications were still assessed to be at high CVD risk strongly suggests that their treatment may have been inadequate."
Professor Tonkin said this research could inform health policy and clinical practice.
"As the greatest absolute risk reduction results from treatment of those at highest risk, we propose that criteria to support use of lipid-lowering medications in those without manifest CVD or diabetes should be revised," he said.
The Medical Journal of Australia