Pharmaco-economic assessment of the HMG-CoA reductase inhibitors.

OBJECTIVE

To perform a comparative pharmaco-economic assessment of two HMG-CoA reductase inhibitors.

DESIGN

A cost-effectiveness analysis was employed using comparative efficacy data from selected clinical trials. A comprehensive international literature search formed the basis for this selection. Criteria for inclusion of clinical trial results in the analysis were set a priori. Acquisition costs used were the recommended reimbursement prices as at September 1994.

MAIN OUTCOME MEASURES

Two outcome measures are reported: (i) the comparative cost-effectiveness in lowering blood lipid concentrations; and (ii) the comparative cost-effectiveness of the medicines when used to achieve a predetermined therapeutic goal.

RESULTS

The average cost per 1% decrease in total cholesterol is 21.9% higher on 10 mg pravastatin daily than on 10 mg simvastatin daily. Similarly the average cost per 1% decrease in low-density lipoprotein (LDL) cholesterol is 23.1% higher on 10 mg pravastatin than on 10 mg simvastatin daily. This difference is consistent throughout the dosage range. The use of incremental doses of simvastatin monotherapy in order to reach a predetermined therapeutic goal (LDL < or = 4.14 mmol/l) is more cost-effective than an equivalent pravastatin dosage regimen. Total treatment costs for simvastatin-treated patients are 3.5% less than for pravastatin-treated patients. More patients on simvastatin are successfully treated; the difference in overall treatment costs per successfully treated patient is 27.9% in favour of simvastatin. Sensitivity analysis shows these results to be stable under extreme scenarios.

CONCLUSIONS

This analysis employed objective comparative efficacy data obtained from peer-reviewed sources to compare the economic and clinical outcomes of simvastatin and pravastatin in the treatment of hypercholesterolaemia. The acquisition cost of simvastatin is 10.3-22.8% higher than an equivalent milligram dose of pravastatin, depending on the dosage used. However, because of the greater milligram potency of simvastatin, it is a more cost-effective alternative. Simvastatin therefore provides better value for money than pravastatin in lowering lipid levels in clinical practice.