Article Text

Cost effectiveness of statins
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1. A S WIERZBICKI, Senior Lecturer in Chemical Pathology
1. T M REYNOLDS, Professor of Chemical Pathology, Queen's Hospital
1. St Thomas's Hospital
2. London SE1 7EH, UK
3. Burton-on-Trent, Staffordshire DE13 0RB, UK
1. D M PICKIN,
2. C J MCCABE,
3. L E RAMSAY,
4. N PAYNE
1. The University of Sheffield
2. School of Health and Related Research
3. Medical Care Research Unit
4. Regent Court, 30 Regent Street
5. Sheffield S1 4DA, UK

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Editor,—The article by Pickin and colleagues is a valuable demonstration of the cost effectiveness of statins in both secondary and primary prevention of coronary heart disease1; however, the study underestimates the benefits of statin treatment. The Scandinavian simvastatin survival study recruited patients with cholesterol between 5 and 8 mmol/l. The cholesterol distribution in coronary heart disease (CHD) patients in the UK is similar to the distribution in the long-term intervention with pravastatin in ischaemic disease (LIPID) study,2 with a range of 4–7 mmol/l, which also showed substantial benefits on mortality. Thus the average dose of 27.4 mg of simvastatin chosen for the cost- benefit analysis is an overstatement of the cost, even before the recent renegotiation of drug prices, as 88% not 67% would be controlled on 20 mg simvastatin. Pravastatin was used at 40 mg in the LIPID study. Although it was not specified in the recruitment criteria, the average calculated risks for patients in the LIPID and the cholesterol and recurrent events (CARE) studies was 2%/year. This is similar to the west of Scotland coronary prevention study (WOSCOPS) primary prevention population, with an average 1.8%/year risk. This happens to be the highest risk population in the UK for CHD and so is not representative of the country at large.3 Primary prevention data do exist for lower risk thresholds than the 3%/year risk advised for treatment, as the Air Force/Texas coronary atherosclerosis prevention study recruited patients,4including women, with an average risk of 1.5%/year, and showed a significant benefit in morbidity. Discrimination by means of lack of evidence of plaque instability is illogical. Unified risk thresholds need to be used for primary and secondary prevention.

The trials all used intention to treat analysis and hence underestimate the benefit of statin treatment, as non-compliance manifests itself as lack of return to collect repeat prescriptions and a reduction in drug costs. It is stated that treatment at 3%/year risk is affordable and logistically possible at £5100 ($8160)/life year saved (LYS). However, treatment at 2%/year risk is unaffordable at £10 700 ($17 120)/LYS. Yet treatment with β blockers for hypertension costs £500–13 000 ($800–20 800)/LYS and renal dialysis is estimated at £28 000 ($44 800)/LYS.5 If rationing is to be instituted it needs to be made explicit and logical.

The analysis is also naive. Solid trial evidence exists for 1.5%/year risk. Denial of drug treatment could be the basis of litigation for negligence, a fast increasing cost to the National Health Service. It would be similar to denial of treatment to smokers.

This article is useful in confirming the health economic benefits of lipid lowering treatment, however, it underestimates the clinical benefits and minimises the problems of such an approach.

## References

This letter was shown to the authors who replied as follows:

Wierzbicki and Reynolds suggest that our study “underestimates the benefits of statin treatment”. Statins produce a constant relative risk reduction in CHD of approximately 30%, in populations with baseline CHD risks as low as 0.6% per annum.1-1 This CHD risk reduction requires a reduction in cholesterol of 20–25%, and is independent of the initial cholesterol distribution. In high risk groups, such as the 4S population,1-2 the absolute risk reduction is obviously higher, with a consequent reduction in the number needed to treat (NNT) and, as we have shown, an increase in cost effectiveness. Wierzbicki and Reynolds correctly point out that the CHD risk in the general UK population is lower than that in 4S patients. This is precisely why treatment needs to be targeted at high risk groups. The important question is at what threshold?

There is no practical and valid method of estimating CHD risk in secondary prevention, nor is it necessary. All have high risk, they are easily identified, and there is general agreement that they are a priority for treatment. Primary prevention is where the debate lies over risk thresholds. The cost effectiveness of treatment is one important consideration in determining the risk threshold, and we have shown how this varies with CHD risk and with the cost of treatment. The recent fall in the price of statins is exactly the eventuality for which our analysis of cost effectiveness by price was designed. In estimating cost effectiveness we have used both the costs and the (intention to treat) benefits taken from trial evidence, rather than speculating on the effectiveness of lower doses. As we pointed out in our paper, our assumption of 100% compliance produces a conservative estimate of cost effectiveness, in line with published recommendations. This assumption is necessary because, although we know that compliance fell over the course of the trials, we do not know the point at which individuals discontinued treatment.

We agree with Wierzbicki and Reynolds that decisions about the threshold for treatment should be logical and explicit, and the data summarised in table 2 of our paper form a sound basis for the development of policy. With statins, as with renal dialysis and other forms of health care, the proportion of the population that will be treated as a consequence of treatment policy, and the total cost of treatment need to be considered, as well as cost effectiveness. The large number of patients, rather than cost effectiveness, provides the principal barrier to affordability of statin treatment. It would be extremely naive to think that the NHS has the resources to treat the 41% of the UK adult population who have an annual CHD risk of greater than 0.6%, and are likely to benefit from statins.1-3 The drug cost alone for this would be greater than £3.5 billion (\$5.6 billion) per annum, despite the recent price reductions, and would represent more than two thirds of the national drugs bill. It would be irresponsible to advocate lower risk thresholds while ignoring the plight of those who have to do the work and find the money to fund it.

## References

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