Is lower and lower better and better? A re-evaluation of the evidence from the Cholesterol Treatment Trialists' Collaboration meta-analysis for low-density lipoprotein Lowering

Mike Rosenbloom Laboratory for Cardiovascular Research, Room H7,22, McGill University Health Centre, Royal Victoria Hospital, 687 Pine Avenue West, Montreal, Quebec, H3A 1A1 Canada.
Journal of Clinical Lipidology (Impact Factor: 3.9). 07/2012; 6(4):303-9. DOI: 10.1016/j.jacl.2012.05.004
Source: PubMed


Researchers from the Cholesterol Treatment Trialists' (CTT) Collaboration have argued for maximal lowering of low-density lipoprotein cholesterol (LDL-C) by the use of pharmacologic agents, with the strongest evidence coming from the five comparison statin studies in their second meta-analysis. The CTT meta-analysis has many strengths but also a number of limitations, which have not been discussed and which, given the clinical implications, require consideration. Among these are: (1) the impact and validity of including revascularizations within a composite primary end point; (2) the inclusion of the A-Z study, whose design does not allow for valid comparisons of two statin regimens; (3) the fact that baseline LDL-C levels in the comparison studies were not low enough to test whether statin therapy reduces risk significantly in groups with an initial low LDL-C; and, most important, (4) authors of the five studies compared doses at the extremes of statin regimens. However, the clinical choice is not between the lowest and the greatest dose of a statin statin regimens, for example, between 10 and 80 mg atorvastatin, but, more realistically, between intermediate and high dose, that is, between 40 and 80 mg atorvastatin. On the basis of the CTT meta-analysis, we calculate that any potential gain from increasing the dose from 40 to 80 mg atorvastatin would be very small, at best a further 2% further reduction in clinical events. The increase in dose, unfortunately, would likely be associated with increased side effects and decreased compliance. Accordingly, whether net benefit would be demonstrable cannot be assumed. It follows that definitive evidence supporting maximal lowering of LDL-C or maximal dose of statins is still lacking and guidelines, if they are to be evidence-based, should acknowledge this uncertainty.

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    • "The lower targets suggested in recent guidelines are based on studies comparing different treatment regimens and on meta-analyses of a large number of statin trials [27••, 28]. Although these studies give good support for the low LDL-C targets, the “lower the better” approach is still under debate [29, 30]. ApoB and non-HDL-C have not been studied as primary targets in randomized studies, but post-hoc analyses suggest that both may be used [31–33] and these analyses form the basis for target levels in guidelines (Table 2). "
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    ABSTRACT: A number of plasma lipid parameters have been used to estimate cardiovascular risk and to be targets for treatment to reduce risk. Most risk algorithms are based on total cholesterol (T-C) or low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein cholesterol (HDL-C), and most intervention trials have targeted the LDL-C levels. Emerging measures, which in some cases may be better for risk calculation and as alternative treatment targets, are apolipoprotein B and non-HDL-C. Other lipid measures that may contribute in risk analysis are triglycerides (TG), lipoprotein(a), and lipoprotein-associated phospholipase A2. The primary treatment target in cardiovascular prevention is LDL-C, and potential alternative targets are apoB and non-HDL-C. In selected individuals at high cardiovascular (CV) risk, TG should be targeted, but HDL-C, Lp(a), and ratios such as LDL-C/HDL-C or apoB/apoAI are not recommended as treatment targets. Lipids should be monitored during titration to targets. Thereafter, lipids should be checked at least once a year or more frequently to improve treatment adherence if indicated. Monitoring of muscle and liver enzymes should be done before the start of treatment. In stable conditions during treatment, the focus should be on clinical symptoms that may alert muscle or liver complications. Routine measurement of CK or ALT is not necessary during treatment with statins.
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