To the Editor: The article by Simpson et al1 did not take into account the difference in the cholesterol-lowering effects of atorvastatin and simvastatin. Atorvastatin at 10 mg has been estimated to be equivalent in potency to 40 mg of simvastatin,2 which would bias the end points chosen for the atorvastastin group after matching. If patients in the simvastatin group collectively had higher cholesterol levels, which seems likely, any further analysis of cost-benefit and conclusions is erroneous. Because Simpson et al did not report cholesterol outcomes, it would be of interest to have them reanalyze their data after adjusting for equivalent dosing. Zhou et al3 have reported that all the statins are effective for secondary prevention after acute myocardial infarction. In their study, atorvastatin was compared to simvastatin, pravastatin, lovastatin, and fluvastatin, and no differences in outcomes were detected. A meta-analysis has demonstrated a 1% reduction in cardiovascular events for each 1% decline in low-density lipoprotein cholesterol (LDL-C) values by statins, leading to the conclusion that the benefits of LDL-C lowering induced by statins are universal.4 Improved outcomes from the use of a high-dose statin vs a moderate-dose statin have already been demonstrated (using atorvastatin as the high-dose agent5), as referenced in the article by Simpson et al. Here again, “apples to apples comparison” was not evaluated. Switching the studied agents and placing atorvastatin as the lower-dose agent could well prove simvastatin as the drug with more favorable outcomes. Comparative effectiveness in the article by Simpson et al cannot be fairly assessed without cholesterol reporting, or at least an approximation of equivalent doses among statins being compared. It is important that comparative effectiveness research not be tainted by unfair comparisons.