Time to benefit: an emerging concept for assessing the efficacy of statin therapy in cardiovascular disease

Efferocytosis in atherosclerosis

Cardiovascular disease is the leading cause of death worldwide, and it commonly results from atherosclerotic plaque progression. One of the increasingly recognized drivers of atherosclerosis is dysfunctional efferocytosis, a homeostatic mechanism responsible for the clearance of dead cells and the resolution of inflammation. In atherosclerosis, the capacity of phagocytes to participate in efferocytosis is hampered, leading to the accumulation of apoptotic and necrotic tissue within the plaque, which results in enlargement of the necrotic core, increased luminal stenosis and plaque inflammation, and predisposition to plaque rupture or erosion. In this Review, we describe the different forms of programmed cell death that can occur in the atherosclerotic plaque and highlight the efferocytic machinery that is normally implicated in cardiovascular physiology. We then discuss the mechanisms by which efferocytosis fails in atherosclerosis and other cardiovascular and cardiometabolic diseases, including myocardial infarction and diabetes mellitus, and discuss therapeutic approaches that might reverse this pathological process.

Evaluation of Time to Benefit of Statins for the Primary Prevention of Cardiovascular Events in Adults Aged 50 to 75 Years: A Meta-analysis

Importance

Guidelines recommend targeting preventive interventions toward older adults whose life expectancy is greater than the intervention's time to benefit (TTB). The TTB for statin therapy is unknown.

Objective

To conduct a survival meta-analysis of randomized clinical trials of statins to determine the TTB for prevention of a first major adverse cardiovascular event (MACE) in adults aged 50 to 75 years.

Data Sources

Studies were identified from previously published systematic reviews (Cochrane Database of Systematic Reviews and US Preventive Services Task Force) and a search of MEDLINE and Google Scholar for subsequently published studies until February 1, 2020.

Study Selection

Randomized clinical trials of statins for primary prevention focusing on older adults (mean age >55 years).

Data Extraction and Synthesis

Two authors independently abstracted survival data for the control and intervention groups. Weibull survival curves were fit, and a random-effects model was used to estimate pooled absolute risk reductions (ARRs) between control and intervention groups each year. Markov chain Monte Carlo methods were applied to determine time to ARR thresholds.

Main Outcomes and Measures

The primary outcome was time to ARR thresholds (0.002, 0.005, and 0.010) for a first MACE, as defined by each trial. There were broad similarities in the definition of MACE across trials, with all trials including myocardial infarction and cardiovascular mortality.

Results

Eight trials randomizing 65 383 adults (66.3% men) were identified. The mean age ranged from 55 to 69 years old and the mean length of follow-up ranged from 2 to 6 years. Only 1 of 8 studies showed that statins decreased all-cause mortality. The meta-analysis results suggested that 2.5 (95% CI, 1.7-3.4) years were needed to avoid 1 MACE for 100 patients treated with a statin. To prevent 1 MACE for 200 patients treated (ARR = 0.005), the TTB was 1.3 (95% CI, 1.0-1.7) years, whereas the TTB to avoid 1 MACE for 500 patients treated (ARR = 0.002) was 0.8 (95% CI, 0.5-1.0) years.

Conclusions and Relevance

These findings suggest that treating 100 adults (aged 50-75 years) without known cardiovascular disease with a statin for 2.5 years prevented 1 MACE in 1 adult. Statins may help to prevent a first MACE in adults aged 50 to 75 years old if they have a life expectancy of at least 2.5 years. There is no evidence of a mortality benefit.

The Effect of Statins on the Functionality of CD4+CD25+FOXP3+ Regulatory T-cells in Acute Coronary Syndrome: A Systematic Review and Meta-analysis of Randomised Controlled Trials in Asian Populations

Acute coronary syndrome (ACS) is characterised by increased effector cells and decreased regulatory T-cells (Tregs). Statins have been shown to be clinically beneficial in ACS patients. This effect could be mediated via the induction of Tregs in ACS patients. The aim of this systemic review and meta-analysis was to evaluate whether statin therapy enhances the frequency of Tregs determined by CD4+CD25+FOXP3+ in this subset of patients. A comprehensive search of PubMed and Embase was performed. Studies were restricted to randomised controlled trials that quantified CD4+CD25+FOXP3+ cell frequency by flow cytometric analysis before and after statin treatment in adults diagnosed with ACS. A minimum of at least two of the conventional markers to identify Tregs was compulsory. Four randomised controlled trials studies (439 participants) were included, all with low-to-moderate risk of bias. Pooled data showed a significant increase in Treg frequency after statin therapy in ACS patients. A further meta-regression and subgroup analysis also showed a negative dose-related effect, and a statin type-related effect (rosuvastatin versus atorvastatin), respectively. The results confirmed that statins positively alter the frequency of Tregs, which may indicate a potential mechanism of their therapeutic effect. However, there was a risk of information bias due to the markers used to identify Tregs, which was not fully explored, therefore, further randomised controlled trials should utilise markers of Tregs, such as the FOXP3 locus (Treg-specific demethylated region), for identification.

Understanding and anticipating lag-time bias in cost-effectiveness studies: the role of time in cost-effectiveness analysis

BACKGROUND

Timely provision of information on the cost-effectiveness of innovations in health care becomes more and more important, resulting in increasing pressure on researchers to provide proof of cost-effectiveness in a short time frame. However, most of these innovations require considerable time and effort to optimally implement leading to a biased "steady state" cost-effectiveness outcome. As decision makers in health care predominantly have a short-term focus, the discrepancy between short-term study outcomes and long-term cost-effectiveness may very well lead to misguided decisions about the adoption of innovations in health care.

METHODS

Factors such as learning effects, capacity constraints, and delayed time to benefit are all related to a short-run timeframe and result in inefficiencies during the implementation of an innovation. These factors and the mechanisms by which they influence the cost-effectiveness outcome are explained for three different types of healthcare innovations.

RESULTS

As standard cost-effectiveness analysis assumes costs and effects to behave constant and representative for an innovation's entire economic lifetime, resulting cost-effectiveness outcomes might give a biased, and often overly pessimistic, reflection of the actual cost-effectiveness of an innovation. This is further amplified by the fact that short-run inefficiencies are most prevalent and impactful during an innovation's earliest stage of operation.

CONCLUSIONS

This study advocates to carefully take into account the different factors contributing to lag-time bias in the design and analysis of cost-effectiveness studies, and to communicate potential biases due to short-run inefficiencies to all stakeholders involved in the decision making process.

Rationalizing prescribing for older patients with multimorbidity: considering time to benefit

Given the growing number of older adults with multimorbidity who are prescribed multiple medications, clinicians need to prioritize which medications are most likely to benefit and least likely to harm an individual patient. The concept of time to benefit (TTB) is increasingly discussed in addition to other measures of drug effectiveness in order to understand and contextualize the benefits and harms of a therapy to an individual patient. However, how to glean this information from available evidence is not well established. The lack of such information for clinicians highlights a critical need in the design and reporting of clinical trials to provide information most relevant to decision making for older adults with multimorbidity. We define TTB as the time until a statistically significant benefit is observed in trials of people taking a therapy compared to a control group not taking the therapy. Similarly, time to harm (TTH) is the time until a statistically significant adverse effect is seen in a trial for the treatment group compared to the control group. To determine both TTB and TTH, it is critical that we also clearly define the benefit or harm under consideration. Well-defined benefits or harms are clinically meaningful, measurable outcomes that are desired (or shunned) by patients. In this conceptual review, we illustrate concepts of TTB in randomized controlled trials (RCTs) of statins for the primary prevention of cardiovascular disease. Using published results, we estimate probable TTB for statins with the future goal of using such information to improve prescribing decisions for individual patients. Knowing the relative TTBs and TTHs associated with a patient's medications could be immensely useful to a clinician in decision making for their older patients with multimorbidity. We describe the challenges in defining and determining TTB and TTH, and discuss possible ways of analyzing and reporting trial results that would add more information about this aspect of drug effectiveness to the clinician's evidence base.

Lipid-independent pleiotropic effects of statins in the management of acute coronary coronary syndromes

Acute coronary syndromes involve a complex interplay between the vessel wall, inflammatory cells, and the coagulation cascade. Statins possess beneficial effects that are independent of low-density lipoprotein cholesterol lowering and that have favorable effects on inflammation, the endothelium, and the coagulation cascade. There is now accumulating evidence that these lipid-independent pleiotropic effects are clinically relevant in the management of acute coronary syndromes.

Beyond lipid lowering: What have we learned about the benefits of statins from the acute coronary syndromes trials?

The long-term benefits for prevention of primary and secondary cardiovascular events achieved by lowering serum cholesterol levels with statins are undisputed. However, results of early clinical trials and preclinical studies suggested the possibility that benefits of treatment with the 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins) may not be entirely due to their effects on low-density lipoprotein (LDL) cholesterol. Since then, large-scale clinical trials of statin treatment for acute coronary syndromes (ACS) have demonstrated early benefits that are associated with aggressive initiation of statin therapy. Support for pleiotropic effects of statins in these trials has been provided not only by these acute effects but also by apparent differences in efficacy between various statin regimens that seem unrelated to their effects on serum cholesterol levels. Analyses of biomarkers of inflammation, oxidation, and thrombosis in samples from patients in these studies have also suggested possible mechanisms underlying the benefits of statins in ACS. This article reviews some of the key statin trials in ACS and assesses the evidence for benefits of these drugs independent of their effects on LDL cholesterol.

The Potential Relevance of the Multiple Lipid-Independent (Pleiotropic) Effects of Statins in the Management of Acute Coronary Syndromes

Emerging data suggest that acute presentations of coronary artery disease may involve a complex interplay between the vessel wall, inflammatory cells, and the coagulation cascade. Although a culprit thrombotic lesion may be treated effectively by antithrombotic therapy and revascularization, this will have little effect on the global processes that determine recurrent events at non-culprit sites. Thus, additional systemic treatment is required to modulate the adverse biological features that are the hallmark of acute coronary syndromes (ACS). Statins possess multiple beneficial effects that are independent of low-density-lipoprotein cholesterol (LDL-C) lowering and that have favorable effects on inflammation, the endothelium, and the coagulation cascade. In the Pravastatin or Atorvastatin Evaluation and Infection Therapy-Thrombolysis In Myocardial Infarction 22 (PROVE IT-TIMI 22) trial, differences were seen based on achieved LDL-C that could be further discriminated by the achieved C-reactive protein level. Studies of non-vascular disease such as multiple sclerosis have shown that statins reduce inflammation, supporting the presence of lipid-independent effects of statins. This review focuses on the potential importance of these effects in the management of ACS.

Early time to benefit with intensive statin treatment: could it be the pleiotropic effects?

Acute coronary syndrome (ACS) is associated with a number of abnormalities in inflammation, endothelial function, and coagulation, all of which appear to be modulated by statins. We examined the time to benefit of different statin regimens in the Pravastatin or Atorvastatin Evaluation and Infection Therapy-Thrombolysis in Myocardial Infarction 22 (PROVE IT-TIMI 22) trial and other ACS trials that compared statin therapies in patients with ACS. In PROVE IT-TIMI 22, apparent clinical benefit was observed as early as 30 days, with significant reduction in all-cause mortality, myocardial infarction, unstable angina requiring rehospitalization, revascularization performed 30 days postrandomization, or stroke observed as early as 4 months. In PROVE IT-TIMI 22, atorvastatin 80 mg lowered both low-density lipoprotein (LDL) cholesterol and C-reactive protein (CRP) at 30 days and 4 months to a greater extent than pravastatin 40 mg. Those who achieved the lowest LDL and the lowest CRP levels at 30 days after ACS had the lowest risk of acute cardiac events. The very early benefits of statin therapy appeared to be correlated with CRP reductions, which may relate to the intensity of the pleiotropic effects of statins.