Cost-effectiveness of prescribing statins according to pharmaceutical benefits scheme criteria.

OBJECTIVES

(i) To analyse how well Pharmaceutical Benefits Scheme (PBS) criteria for prescribing lipid-lowering therapy identify people most at risk of coronary heart disease (CHD); and (ii) to determine the cost-effectiveness of primary prevention therapy with pravastatin according to these criteria in Australia.

DESIGN

(i) Analysis of targeting of CHD risk according to PBS criteria; (ii) cost-effectiveness analysis for pravastatin as primary preventive therapy (40 mg/day), with a 20-year projection from 1999.

PARTICIPANTS

(i) Men and women aged 25-69 years from the 1989 National Heart Foundation Risk Factor Prevalence Survey; (ii) Australian men and women, aged 25-85 years, excluding those with diabetes and existing CHD.

MAIN OUTCOME MEASURES

(i) Proportion eligible for lipid lowering treatment according to PBS criteria within 15-year risk of CHD mortality groups; (ii) average net cost in Australian dollars ($) per year of life saved (YOLS), with 80% uncertainty ranges (UR).

RESULTS

(i) PBS criteria do not adequately identify those most at risk of CHD, as only 61% of Australians (aged 25-69 years) with a greater than 10% 15-year risk of CHD mortality were eligible for treatment; and 11% of those at low risk of CHD mortality (< 2.5% over 15 years) were eligible for treatment. (ii) Cost-effectiveness of treatment according to PBS criteria was estimated at $110,000 (80% UR, $96,000-$150,000) per YOLS for men and $87,000 (80% UR, $80,000-$130,000) per YOLS for women. As an indicator of the likely recurrent annual costs, total first-year treatment costs (excluding the costs of non-compliers) were estimated at $940 million. Assuming compliance of 50%, cost-effectiveness of treatment was markedly improved using 32.5% 15-year risk of CHD mortality as a cut-off, with ratios of $31,000 (80% UR, $27,000-$40,000) per YOLS for men and $39,000 (80% UR, $33,000-$53,000) per YOLS for women. First-year treatment costs of $940 million were the same as treating according to PBS criteria, but absolute health impact in terms of deaths averted and years of life saved was more than doubled.

CONCLUSIONS

While PBS criteria do target patients at risk of CHD, there is room for improvement in identifying those most at risk of CHD, and treatment according to PBS criteria is not likely to be the most cost-effective. For optimal cost-effectiveness, targeting of therapy for primary CHD prevention needs to be based on population-specific, multivariable risk.