Your cardiology unit needs to construct guidelines within a finite budget about which patients are likely to benefit the most from cholesterol-lowering statin drugs. You are aware of the “4S” (Scandinavian simvastatin survival study) that showed reduced mortality for men and women with statins, but this study did not include cost information. You formulate the question, for patients with increased cholesterol: “How much does simvastatin cost per year of life gained?”
You conduct a MEDLINE search for (simvastatin and coronary heart disease and cost effectiveness) as text words, and find a recent study based upon the 4S study New England Journal of Medicine. 1997;336:332-336.
Read the article and decide:
- Is this evidence about cost effectiveness valid?
- Is this valid evidence about cost effectiveness important in relation to your problem?
- Can you apply this valid and important evidence about cost effectiveness to your patients?
Completed Economic Analysis Worksheet for Evidence-Based Purchasing
Johannesson M, Jönsson B, Kjekshus J, Olsson AG et al. Cost effectiveness of simvastatin treatment to lower cholesterol levels in patients with coronary heart disease.
New England Journal of Medicine. 1997;336:332-336.
Are the results of this economic analysis valid?
- Did the analysis provide a full economic comparison of health care strategies?
- Kind of. Direct health costs as well as lost income from illness were included. Costs not included were explained (quality of life costs, extra health costs from years of life gained). However, the study did not compare costs with status quo. It only broadly compared the costs of treating cholesterol with statins with those of treating other common conditions.
- Were the costs and outcomes properly measured and valued?
- Yes. The Scandinavian Simvastatin Survival (4S) Study was used for effectiveness information, itself a reasonably reliable multicentre randomised controlled trial. Follow up was 5 years. The unit being assessed were years of life in people with existing heart disease taking simvastatin. Costs were assessed using hospital cost data and income from patients’ work status, recorded every 6 months (page 334). The discount rate was 5%.
- Was appropriate allowance made for uncertainties in the analysis?
- Yes. Sensitivity analysis (table 5) was conducted to see what effects different assumptions might have on the results, including assumptions about non-health costs, follow up costs and differences between Swedish and US drug prices.
- Are estimates of costs and outcomes related to the baseline risk in the treatment population?
- Yes – Table 1.
Are the valid results of this economic analysis important?
- What were the incremental costs and outcomes of each strategy?
- The authors combine Swedish direct and indirect costs for first and subsequent years at a discount rate of 5%. Costs are calculated at the 1995 exchange rate with the $US for different aspects of care for three age groups and both sexes, made explicit (for comparison in other settings) in Tables 2-5.
- Do incremental costs and outcomes differ between subgroups?
- Yes. Costs were calculated for different risk groups. Older people (who have not so many years of life to gain) and women (at lower risk of events) are more expensive.
- How much does allowing for uncertainty change the results?
- See sensitivity analysis – Table 5. Different assumptions change the range of costs a lot, but not so much as to reverse the conclusions.
Can you apply this valid, important evidence about prognosis in caring for your patient?
- Are the treatment benefits worth the harms and costs?
- Probably – although it would be important for purchasers to consider the costs within their own country.
- Could my patients expect similar health outcomes?
- Probably, unless the rate of coronary heart disease in the population is much lower (or higher) than those reported here, in which case the cost effectiveness per year would be lower (or higher).
- Could I expect similar costs?
- In Western Europe, probably. US (more expensive) drug prices and health care costs would need to be calculated from the Tables given to see whether the cost effectiveness was still as great. Table 5 includes a sensitivity analysis for US drug prices.
The authors note that the results only apply to a high risk population – i.e. those with a history of heart disease – as the cost effectiveness falls as absolute risk of cardiac events falls.
Coronary Heart Disease: Simvastatin is cost effective in men and women at high risk of coronary events.
Purchasing Bottom Line
Simvastatin is cost effective in men and women at high risk of cardiac events compared with other treatments for common conditions.
Johannesson M, JÃ¶nsson B, Kjekshus J, Olsson AG et al. Cost effectiveness of simvastatin treatment to lower cholesterol levels in patients with coronary heart disease.
New England Journal of Medicine. 1997;336:332-336.
How much does simvastatin cost per year of life gained?
MEDLINE search using cost effectiveness, simvastatin, coronary heart disease.
A cost effectiveness analysis, based upon the effectiveness data from the Scandinavian Simvastatin Survival (4S) Study, using a Markov* incremental cost model to assess the costs per year of life gained using simvastatin in people at high risk of cardiac events (men and women 35 to 70 years with total cholesterol levels of 213 to 309 mg/dl with a history of angina pectoris or acute myocardial infarction). Direct and indirect costs were calculated from Swedish data at the 1995 exchange rate with the $US. A 5% discount rate was used to calculate costs of future years of life gained. Sensitivity analysis was conducted taking into account differences in risk reduction of cardiac event; risk of mortality after event; inclusion of health costs in gained years; morbidity associated costs; intervention costs with follow up, screening, and US drug prices, and discount rates of 0%, 5%, and 10% per year.
- Markov model: A model of a sequence of events, in which the probability of an event occurring in the future depends upon a the occurrence of a (specified) preceding event.
|Total cholesterol before treatment (mg/dl)||Age 35||Age 59||Age 70|
|Analysis of direct costs ($US)|
|Analysis of direct and indirect costs|
- The main results (tabled above) do not take into account costs of extra years gained from patients not dying, nor quality of life effects, so they do not compare the cost effectiveness of simvastatin versus no or alternative treatment.
- Decision makers in other countries would need to consider their own costs compared to those outlined in this study (outlined in Table 2).
- The results apply only to people at high risk of cardiac events, not the general population. The lower cost effectiveness in women is due predominantly to their lower risk of events than men from 35 years.
Anna Donald and Sam Vincent