Economic evaluation of ezetimibe combined with simvastatin for the treatment of primary hypercholesterolaemia

Cost-effectiveness of Ezetimibe plus statin lipid-lowering therapy: A systematic review and meta-analysis of cost-utility studies

In addition to statin therapy, Ezetimibe, a non-statin lipid-modifying agent, is increasingly used to reduce low-density lipoprotein cholesterol and atherosclerotic cardiovascular disease risk. Literature suggests the clinical effectiveness of Ezetimibe plus statin (EPS) therapy; however, primary evidence on its economic effectiveness is inconsistent. Hence, we pooled incremental net benefit to synthesise the cost-effectiveness of EPS therapy. We identified economic evaluation studies reporting outcomes of EPS therapy compared with other lipid-lowering therapeutic agents or placebo by searching PubMed, Embase, Scopus, and Tufts Cost-Effective Analysis registry. Using random-effects meta-analysis, we pooled Incremental Net Benefit (INB) in the US $ with a 95% confidence interval (CI). We used the modified economic evaluations bias checklist and GRADE quality assessment for quality appraisal. The pooled INB from twenty-one eligible studies showed that EPS therapy was significantly cost-effective compared to other lipid-lowering therapeutic agents or placebo. The pooled INB (95% CI) was $4,274 (621 to 7,927), but there was considerable heterogeneity (I² = 84.21). On subgroup analysis EPS therapy is significantly cost-effective in high-income countries [$4,356 (621 to 8,092)], for primary prevention [$4,814 (2,523 to 7,106)], and for payers’ perspective [$3,255 (571 to 5,939)], and from lifetime horizon [$4,571 (746 to 8,395)]. EPS therapy is cost-effective compared to other lipid-lowering therapeutic agents or placebo in high-income countries and for primary prevention. However, there is a dearth of evidence from lower-middle-income countries and the societal perspective.

Economic evaluation of ezetimibe treatment in combination with statin therapy in the United States

AIMS

This study assessed the cost-effectiveness of ezetimibe with statin therapy vs statin monotherapy from a US payer perspective, assuming the impending patent expiration of ezetimibe.

METHODS

A Markov-like economic model consisting of 28 distinct health states was used. Model population data were obtained from US linked claims and electronic medical records, with inclusion criteria based on diagnostic guidelines. Inputs came from recent clinical trials, meta-analyses, and cost-effectiveness analyses. The base-case scenario was used to evaluate the cost-effectiveness of adding ezetimibe 10 mg to statin in patients aged 35-74 years with a history of coronary heart disease (CHD) and/or stroke, and with low-density lipoprotein cholesterol (LDL-C) levels ≥70 mg/dL over a lifetime horizon, assuming a 90% price reduction of ezetimibe after 1 year to take into account the impending patent expiration in the second quarter of 2017. Sub-group analyses included patients with LDL-C levels ≥100 mg/dL and patients with diabetes with LDL-C levels ≥70 mg/dL.

RESULTS

The lifetime discounted incremental cost-effectiveness ratio (ICER) for ezetimibe added to statin was $9,149 per quality-adjusted life year (QALY) for the base-case scenario. For patients with LDL-C levels ≥100 mg/dL, the ICER was $839/QALY; for those with diabetes and LDL-C levels ≥70 mg/dL, it was $560/QALY. One-way sensitivity analyses showed that the model was sensitive to changes in cost of ezetimibe, rate reduction of non-fatal CHD, and utility weight for non-fatal CHD in the base-case and sub-group analyses.

LIMITATIONS

Indirect costs or treatment discontinuation estimation were not included.

CONCLUSIONS

Compared with statin monotherapy, ezetimibe with statin therapy was cost-effective for secondary prevention of CHD and stroke and for primary prevention of these conditions in patients whose LDL-C levels are ≥100 mg/dL and in patients with diabetes, taking into account a 90% cost reduction for ezetimibe.

A systematic literature review of methods of incorporating mortality in cost-effectiveness analyses of lipid-lowering therapies

AIMS

Cost effectiveness analysis (CEA) is a useful tool for estimating the value of an intervention in relation to alternatives. In cardiovascular disease (CVD), CEA is especially important, given the high economic and clinical burden. One key driver of value is CVD mortality prevention. However, data used to inform CEA parameters can be limited, given the difficulty in demonstrating statistically significant mortality benefit in randomized clinical trials (RCTs), due in part to the frequency of fatal events and limited trial durations. This systematic review identifies and summarizes whether published CVD-related CEAs have incorporated mortality benefits, and the methodology among those that did.

MATERIALS AND METHODS

A systematic literature review was conducted of CEAs of lipid-lowering therapies published between 2000-2017. Health technology assessments (HTA) and full-length manuscripts were included, and sources of mortality data and methods of applying mortality benefits were extracted. Results were summarized as proportions of articles to articulate common practices in CEAs of CVD.

RESULTS

This review identified 100 studies for inclusion, comprising 93 full-length manuscripts and seven HTA reviews. Among these, 99% assumed a mortality benefit in the model. However, 87 of these studies that incorporated mortality differences did so despite the trials used to inform model parameters not demonstrating statistically significant differences in mortality. None of the 12 studies that used statistically significant findings from an individual RCT were based on active control studies. In a sub-group analysis considering the 60 CEAs that incorporated a direct mortality benefit, 48 (80%) did not have RCT evidence for statistically significant benefit in CVD mortality.

LIMITATIONS AND CONCLUSIONS

The finding that few CEA models included mortality inputs from individual RCTs of lipid-lowering therapy may be surprising, as one might expect that treatment efficacy should be based on robust clinical evidence. However, regulatory requirements in CVD-related RCTs often lead to insufficient sample sizes and observation periods for detecting a difference in CVD mortality, which results in the use of intermediate outcomes, composite end-points, or meta-analysis to extrapolate long-term mortality benefit in a lifetime CEA.

A Systematic Review of Cardiovascular Outcomes-Based Cost-Effectiveness Analyses of Lipid-Lowering Therapies

BACKGROUND

Previous reviews have evaluated economic analyses of lipid-lowering therapies using lipid levels as surrogate markers for cardiovascular disease. However, drug approval and health technology assessment agencies have stressed that surrogates should only be used in the absence of clinical endpoints.

OBJECTIVE

The aim of this systematic review was to identify and summarise the methodologies, weaknesses and strengths of economic models based on atherosclerotic cardiovascular disease event rates.

METHODS

Cost-effectiveness evaluations of lipid-lowering therapies using cardiovascular event rates in adults with hyperlipidaemia were sought in Medline, Embase, Medline In-Process, PubMed and NHS EED and conference proceedings. Search results were independently screened, extracted and quality checked by two reviewers.

RESULTS

Searches until February 2016 retrieved 3443 records, from which 26 studies (29 publications) were selected. Twenty-two studies evaluated secondary prevention (four also assessed primary prevention), two considered only primary prevention and two included mixed primary and secondary prevention populations. Most studies (18) based treatment-effect estimates on single trials, although more recent evaluations deployed meta-analyses (5/10 over the last 10 years). Markov models (14 studies) were most commonly used and only one study employed discrete event simulation. Models varied particularly in terms of health states and treatment-effect duration. No studies used a systematic review to obtain utilities. Most studies took a healthcare perspective (21/26) and sourced resource use from key trials instead of local data. Overall, reporting quality was suboptimal.

CONCLUSIONS

This review reveals methodological changes over time, but reporting weaknesses remain, particularly with respect to transparency of model reporting.

Hypolipidemic Effect of a Blue-Green Alga (Nostoc commune) Is Attributed to Its Nonlipid Fraction by Decreasing Intestinal Cholesterol Absorption in C57BL/6J Mice

We previously demonstrated that Nostoc commune var. sphaeroids Kützing (NO), a blue-green alga (BGA), exerts a hypolipidemic effect in vivo and its lipid extract regulates the expression of genes involved in cholesterol and lipid metabolism in vitro. The objective of this study was to investigate whether the hypolipidemic effect of NO is attributed to an algal lipid or a delipidated fraction in vivo compared with Spirulina platensis (SP). Male C57BL/6J mice were fed an AIN-93M diet containing 2.5% or 5% of BGA (w/w) or a lipid extract equivalent to 5% of BGA for 4 weeks to measure plasma and liver lipids, hepatic gene expression, intestinal cholesterol absorption, and fecal sterol excretion. Plasma total cholesterol (TC) was significantly lower in 2.5% and 5% NO-fed groups, while plasma triglyceride (TG) levels were decreased in the 5% NO group compared with controls. However, neither NO organic extract (NOE) nor SP-fed groups altered plasma lipids. Hepatic mRNA levels of sterol regulatory element-binding protein 2, 3-hydroxy-3-methyl-glutaryl-CoA reductase (HMGR), carnitine palmitoyltransferase-1α, and acyl-CoA oxidase 1 were induced in 5% NO-fed mice, while there were no significant changes in hepatic lipogenic gene expression between groups. NO, but not NOE and SP groups, significantly decreased intestinal cholesterol absorption. When HepG2 cells and primary mouse hepatocytes were incubated with NOE and SP organic extract (SPE), there were marked decreases in protein levels of HMGR, low-density lipoprotein receptor, and fatty acid synthase. In conclusion, the nonlipid fraction of NO exerts TC and TG-lowering effects primarily by inhibiting intestinal cholesterol absorption and by increasing hepatic fatty acid oxidation, respectively.

Cost-effectiveness of adding ezetimibe to atorvastatin vs switching to rosuvastatin therapy in Portugal

BACKGROUND

Statin monotherapy is the mainstay of low-density lipoprotein cholesterol (LDL-C) management for high cardiovascular risk patients in Portugal; however, several therapeutic options are available and predicted to have different clinical and economic impacts. The aim of this study was to evaluate the cost-effectiveness of adding ezetimibe 10 mg (EZ10) to atorvastatin 10 or 20 mg (A10/20) vs switching to rosuvastatin 10 or 20 mg (R10/20) in Portuguese patients with coronary heart disease (CHD) and/or diabetes who are currently above the LDL-C goal.

METHODS

A Markov model was used to describe CHD disease progression and the lifetime costs and utilities associated with each disease state were used to estimate the gains in life-years and quality-adjusted life-years (QALYs), as well as the incremental cost-effectiveness ratio (ICER), of the two treatment regimens. Model inputs, such as age, gender, and prevalence of cardiovascular risk factors of the dyslipidemic Portuguese patients were obtained from the Portuguese cohort of the Dyslipidemia International Study (DYSIS). The efficacy of each treatment regimen, the cost of drugs and of treating CHD events, and the utilities for each disease state were derived from published sources.

RESULTS

The estimated lifetime discounted number of QALYs gained by patients treated with A10/20 was 8.70, while in those switching to R10/20 it was 8.81 and in those adding EZ10 it was 8.93. Discounted total health costs were estimated to be €11,131 for A10/20, but €14,511 and €16,571 for R10/20 and A10/20 + EZ10, respectively. The ICER of adding ezetimibe vs switching to rosuvastatin was €16,465/QALY. Based on the Portuguese cost-effectiveness willingness-to-pay threshold of €30,000/QALY, adding ezetimibe vs switching to rosuvastatin would be a cost-effective use of resources in Portugal. Sensitivity analyses in patients with differing clinical histories (CHD or diabetes or both) yielded similar values, with no ICER over €30,000/QALY.

CONCLUSIONS

From the perspective of the National Health Service, prescribing ezetimibe to high cardiovascular risk patients being treated with atorvastatin vs switching them to rosuvastatin is projected to be a cost-effective use of resources in Portugal.

Using health state utility values in models exploring the cost-effectiveness of health technologies

BACKGROUND

To improve comparability of economic data used in decision making, some agencies recommend that a particular instrument should be used to measure health state utility values (HSUVs) used in decision-analytic models. The methods used to incorporate HSUVs in models, however, are often methodologically poor and lack consistency. Inconsistencies in the methodologies used will produce discrepancies in results, undermining policy decisions informed by cost per quality-adjusted life-years.

OBJECTIVE

To provide an overview of the current evidence base relating to populating decision-analytic models with HSUVs.

FINDINGS

Research exploring suitable methods to accurately reflect the baseline or counterfactual HSUVs in decision-analytic models is limited, and while one study suggested that general population data may be appropriate, guidance in this area is poor. Literature describing the appropriateness of different methods used to estimate HSUVs for combined conditions is growing, but there is currently no consensus on the most appropriate methodology. While exploratory analyses suggest that a statistical regression model might improve accuracy in predicted values, the models require validation and testing in external data sets. Until additional research has been conducted in this area, the current evidence suggests that the multiplicative method is the most appropriate technique. Uncertainty in the HSUVs used in decision-analytic models is rarely fully characterized in decision-analytic models and is generally poorly reported.

CONCLUSIONS

A substantial volume of research is required before definitive detailed evidence-based practical advice can be provided. As the methodologies used can make a substantial difference to the results generated from decision-analytic models, the differences and lack of clarity and guidance will continue to lead to inconsistencies in policy decision making.