Response to Study highlights need for considered clinical approach to statin switching

Abstract

To the Editor: We thank Dr Lloyd for her response in which she highlights the importance of carefully screening patients before switching from atorvastatin to simvastatin. Our study (1) was prompted by the ever-increasing pressure from many Primary Care Trusts across the UK for doctors to switch patients from atorvastatin to simvastatin for cost-saving purposes. As we point out in our original study, however, such switches need to be considered on an individual basis. From dosing studies we know that simvastatin 40 mg lowers low-density lipoprotein cholesterol (LDL-C) by 3% more than atorvastatin 10 mg and 4% less than atorvastatin 20 mg. However, simvastatin 40 mg has a larger high-density lipoprotein cholesterol (HDL-C) raising effect than any atorvastatin dose (10–80 mg) (2–5). Our study was a careful audit of current practice and was not designed to be a clinical trial. Nevertheless, we did see a small increase in both the total cholesterols (0.18 ± 0.7 mmol/l) and HDL-C (0.046 ± 0.2 mmol/l) in the 19 patients switched from atorvastatin 20 mg to simvastatin 40 mg. There were, however, no new diagnoses of coronary heart disease (CHD) or cardiovascular events in these patients and the rise in HDL-C might be important because a 1% increase in HDL-C is associated with a 2–3% decrease in CHD risk while a 1% decrease in LDL-C is associated with a 1% decrease in CHD risk (6). We agree entirely with the findings of Butler and Wainwright (7) that it is not appropriate to switch high-dose atorvastatin to moderate doses of simvastatin in patients with known coronary artery disease. We excluded all patients taking more than 20 mg atorvastatin and those on 10 or 20 mg who had either failed to reach or were only just below the General Medical Services (GMS) cholesterol target. As a result, only 69% of the patients taking atorvastatin 10 mg and 43% of those taking 20 mg were switched to simvastatin. The finding that the switch was successful in this group of patients was precisely the purpose of the study and it now provides support for the already widespread practice of switching from low-dose atorvastatin to simvastatin providing appropriate efforts are made to screen patients and exclude those who are unsuitable.