Immediate Versus 5-Year Risk-Guided Initiation of Treatment for Primary Prevention of Cardiovascular Disease for Australians Aged 40 Years: A Health Economic Analysis.

Abstract

Background and objective: Current Australian cardiovascular disease (CVD) prevention guidelines calculate 5-year CVD risk and recommend treatment when risk crosses specific thresholds. This may leave risk factors untreated for people with a low short-term (i.e. 5 years), but high long-term (i.e. lifetime), risk of CVD. We aimed to evaluate the cost effectiveness of intervention for risk factor control at age 40 years (regardless of calculated risk) compared to intervention for risk factor control at the age recommended by contemporary Australian CVD prevention guidelines (when the 5-year CVD risk reaches 10%) across a range of individual risk factor profiles.

Methods: We used a causal microsimulation model populated with 108 different risk factor profiles, each replicated 10,000 times. Model data were derived from the UK Biobank study and published sources. The primary causal relationships factored in were those of low-density lipoprotein-cholesterol and systolic blood pressure with CVD (defined as myocardial infarction or stroke). The model simulated the ageing of individuals from 40 to 85 years. We calculated years of life lived, quality-adjusted life-years gained, incremental healthcare costs and the incremental cost-effectiveness ratio when low-density lipoprotein-cholesterol and blood pressure were controlled from age 40 years compared to initiation of treatment as recommended by Australian guidelines. The main side effect in the model was an increased risk of type 2 diabetes mellitus from statin use. The trade-off between reduced CVD and increased type 2 diabetes was summarised via quality-adjust life-years. Incremental cost-effectiveness ratios were compared to the Australian willingness-to-pay threshold of AU$28,000 per quality-adjust life-year gained. We adopted a healthcare perspective (2022 AUD) and discounted results at 3% annually.

Results: An earlier intervention meaningfully prevented CVD in all but the lowest risk individuals. Intervention at age 40 years versus age when the 5-year CVD risk reaches 10% led to an increase in quality-adjust life-years for 37/54 female individuals and 44/54 male individuals simulated and an increase in years of life lived (i.e. life expectancy) for 46/54 female individuals and 47/54 male individuals simulated. Earlier intervention was also cost effective in 5/54 female individuals and 17/54 male individuals.

Conclusions: Current guidelines may result in certain individuals with a lower 5-year, but higher lifetime, risk of CVD being overlooked for earlier cost-effective interventions to prevent CVD.