Which interventions offer best value for money in primary prevention of cardiovascular disease?

Abstract

Background: Despite many decades of declining mortality rates in the Western world, cardiovascular disease remains the leading cause of death worldwide. In this research we evaluate the optimal mix of lifestyle, pharmaceutical and population-wide interventions for primary prevention of cardiovascular disease.

Methods and findings: In a discrete time Markov model we simulate the ischaemic heart disease and stroke outcomes and cost impacts of intervention over the lifetime of all Australian men and women, aged 35 to 84 years, who have never experienced a heart disease or stroke event. Best value for money is achieved by mandating moderate limits on salt in the manufacture of bread, margarine and cereal. A combination of diuretic, calcium channel blocker, ACE inhibitor and low-cost statin, for everyone with at least 5% five-year risk of cardiovascular disease, is also cost-effective, but lifestyle interventions aiming to change risky dietary and exercise behaviours are extremely poor value for money and have little population health benefit.

Conclusions: There is huge potential for improving efficiency in cardiovascular disease prevention in Australia. A tougher approach from Government to mandating limits on salt in processed foods and reducing excessive statin prices, and a shift away from lifestyle counselling to more efficient absolute risk-based prescription of preventive drugs, could cut health care costs while improving population health.

Figure 1. The cost-effectiveness acceptability frontier, shown for values of the cost-effectiveness threshold up to $150,000/DALY.

Addition of the interventions that are not visible on the graph, is not optimal until much higher cost-effectiveness thresholds (dietary advice above $2.4 million/DALY and phytosterol margarine above $6.7 million/DALY).

Figure 2. The cost-effectiveness of current practice and the optimal intervention pathway (NB. CCB – calcium channel blocker; ACEi – ACE inhibitor; CHHP – community heart health program).

Interventions are added to the mix in order of cost-effectiveness, thus the pathway reflects the efficiency frontier. The pathway is shown as a solid line where the incremental cost-effectiveness of adding an intervention to the mix is under the cost-effectiveness threshold of $50,000/DALY, and shown as a dashed line where the addition of the next intervention is not cost-effectiveness (i.e. it exceeds the threshold of $50,000/DALY).

Figure 3. Sensitivity of the optimal pathway to increased and decreased discounting (5% and 0%), to the addition of other non-cardiovascular health care costs in added years of life, the measurement of health gain in QALYs rather than DALYs, and to a reduction in the cost of statin drugs to the much lower price in New Zealand (NB. the order of interventions is altered only by the reduction in statin price, with statins becoming a more cost-effective intervention option than the blood pressure-lowering drugs).