Models for describing relations among the various statin drugs, low-density lipoprotein cholesterol lowering, pleiotropic effects, and cardiovascular risk.

Five models are proposed to describe the relations among statins, pleiotropic effects, low-density lipoprotein (LDL) cholesterol lowering, and cardiovascular risk reduction. On the basis of the evidence available, the pleiotropic effects of statins do not appear to reduce cardiovascular risk more than would be predicted from LDL cholesterol lowering alone, which suggests that model 1 is not a valid model. Although most attention has focused on models 2 through 4, most data to date support model 3 for describing the relation between statins, inflammation, and cardiovascular risk. Stronger consideration should also be given to model 5, in which pleiotropic effects are the result of cardiovascular risk reduction in and of itself. It may be that other models are operative for nonatherosclerotic inflammatory disorders. However, beneficial effects of statins on rheumatologic or other noncardiovascular may still be due to effects of cholesterol reduction on the immune system, as in model 3. More high-quality research is needed to determine the role of statin pleiotropic effects in cardiovascular risk reduction. Well-designed animal studies can help elucidate potential mechanisms, which will then require confirmation in human studies with cardiovascular event outcomes. Substudies of cardiovascular end point trials and mechanistic studies should be methodologically sound and designed to test specific models. To sort out the independence of pleiotropic effects from LDL cholesterol lowering, studies will need to achieve similar LDL cholesterol reductions in each treatment group. It may be that the biologic impact of a specific pleiotropic effect is mediated by >1 model. Ultimately, once a predominant model has been identified for a given pleiotropic effect, long-term studies would be needed to evaluate the relative contributions of various pleiotropic effects to cardiovascular risk reduction. These findings may reveal new targets for the development of new agents that will prove effective for reducing cardiovascular events when added to LDL cholesterol lowering. To date, little evidence supports consideration of statin pleiotropic effects in clinical decision making. In conclusion, LDL cholesterol is currently the only reliable marker for statin effects on cardiovascular risk reduction. The focus should remain on closing the treatment gap and improving adherence to therapies directed at lowering LDL cholesterol and non-high-density lipoprotein cholesterol to reduce the burden of cardiovascular disease.