Using cost-effectiveness analysis for formulary decision making: from theory into practice

A brief guide to the selection of quality of life instrument

There are numerous quality of life (QOL) scales. Because QOL experts are often partial to their own scales, researchers need to be able to select scales for themselves. Scales best suited for longitudinal purposes (clinical trials and audit) have different properties to those suited for cross-sectional studies (population and correlational studies and clinical use). The reason and logic of these differences is explained. For longitudinal use, researchers need to consider the relationship between item set, population and treatment; scales can be short, floor and ceiling effects must be avoided, and there should be extended response options. For cross-sectional use scales should have a wide range of items, should be longer, and there are no adverse floor and ceiling effects, and response options can be simpler to allow a larger set of items.

[Cost-effectiveness of atorvastatin against simvastatin as hypolipemic treatment in hypercholesterolemic patients in primary care]

OBJECTIVE

To perform an economics evaluation of lipid-lowering therapy with atorvastatin and simvastatin in patients with hypercholesterolemia in primary care setting.

DESIGN

Cost-effectiveness analysis (CEA) has been carried out by means of an open, random, prospective, "real world" study, with hypercholesterolemic patients (total cholesterol [TC] > 240 mg/dl and cLDL > 160 mg/dl).

PATIENTS

A total of 92 patients were included (44.8% males), with a mean age of 64.9 +/- 9.4 years old (mean +/- standard deviation). 41.4% were diabetics, 62.1% hypertensives and 16.1% smokers.

INTERVENTIONS

Patients were allocated to simvastatin 20 mg/day (44) and atorvastatin. 10 mg/day (48) for 6 months. ASSESSMENT AND MAIN RESULTS: Both therapies reduced significantly cLDL, TC and triglycerides at the end of the study. Atorvastatin reduced lipids faster than simvastatin at 3 months (p < 0.05), but significant differences could not be observed at 6 months. Atorvastatin reduced cLDL levels by 21.5 +/- 13.2% and 23.8 +/- 13.9% at 3 and 6 months, respectively, versus 16.4 +/- 14.2% and 22.8 +/- 10.8% with simvastatin. By these reductions, 54.2% of patients treated with atorvastatin and 50.0% of those allocated to simvastatin reached therapeutic goals of cLDL control. Atorvastatin 10 mg was more cost-effective than simvastatin 20 mg; 95,406 versus 101,335 pts per patient reaching therapeutic goals, respectively, which means that simvastatin need an extra cost of 24,833 pts per patient reaching therapeutic goals to be as efficient as atorvastatin. Sensitivity analysis to control for uncertainty confirmed the results of cost-effectiveness analysis.

CONCLUSIONS

Both statins were effective as lipid-lowering agents. However, atorvastatin 10 mg was more efficient than simvastatin 20 mg due to a better cost-effectiveness ratio.