Cost-effectiveness of clopidogrel in myocardial infarction with ST-segment elevation: A European model based on the CLARITY and COMMIT trials

The Role of Clopidogrel in 2020: A Reappraisal

Antiplatelet therapy is the mainstay of treatment and secondary prevention of cardiovascular disease (CVD), including acute coronary syndrome (ACS), transient ischemic attack (TIA) or minor stroke, and peripheral artery disease (PAD). The P2Y12 inhibitors, of which clopidogrel was the first, play an integral role in antiplatelet therapy and therefore in the treatment and secondary prevention of CVD. This review discusses the available evidence concerning antiplatelet therapy in patients with CVD, with a focus on the role of clopidogrel. In combination with aspirin, clopidogrel is often used as part of dual antiplatelet therapy (DAPT) for the secondary prevention of ACS. Although newer, more potent P2Y12 inhibitors (prasugrel and ticagrelor) show a greater reduction in ischemic risk compared with clopidogrel in randomized trials of ACS patients, these newer P2Y12 inhibitors are often associated with an increased risk of bleeding. Deescalation of DAPT by switching from prasugrel or ticagrelor to clopidogrel may be required in some patients with ACS. Furthermore, real-world studies of ACS patients have not confirmed the benefits of the newer P2Y12 inhibitors over clopidogrel. In patients with very high-risk TIA or stroke, short-term DAPT with clopidogrel plus aspirin for 21-28 days, followed by clopidogrel monotherapy for up to 90 days, is recommended. Clopidogrel monotherapy may also be used in patients with symptomatic PAD. In conclusion, there is strong evidence supporting the use of clopidogrel antiplatelet therapy in several clinical settings, which emphasizes the importance of this medication in clinical practice.

Which Costs Matter? Costs Included in Economic Evaluation and their Impact on Decision Uncertainty for Stable Coronary Artery Disease

BACKGROUND

Variation exists in the resource categories included in economic evaluations, and National Institute for Health and Care Excellence (NICE) guidance suggests the inclusion only of costs related to the index condition or intervention. However, there is a growing consensus that all healthcare costs should be included in economic evaluations for Health Technology Assessments (HTAs), particularly those related to extended years of life.

OBJECTIVE AND METHODS

We aimed to quantify the impact of a range of cost categories on the adoption decision about a hypothetical intervention, and uncertainty around that decision, for stable coronary artery disease (SCAD) based on a dataset comprising 94,966 patients. Three costing scenarios were considered: coronary heart disease (CHD) costs only, cardiovascular disease (CVD) costs and all costs. The first two illustrate different interpretations of what might be regarded as related costs.

RESULTS

Employing a 20-year time horizon, the highest mean expected incremental cost was when all costs were included (£2468) and the lowest when CVD costs only were included (£2377). The probability of the treatment being cost effective, estimating health opportunity costs using a ratio of £30,000 per quality-adjusted life-year (QALY), was different for each of the CHD (70%) costs, CVD costs (73%) and all costs (56%) scenarios. The results concern a hypothetical intervention and are illustrative only, as such they cannot necessarily be generalised to all interventions and diseases.

CONCLUSIONS

Cost categories included in an economic evaluation of SCAD impact on estimates of both cost effectiveness and decision uncertainty. With an aging and co-morbid population, the inclusion of all healthcare costs may have important ramifications for the selection of healthcare provision on economic grounds.

Modeling hard clinical end-point data in economic analyses

OBJECTIVE

The availability of hard clinical end-point data, such as that on cardiovascular (CV) events among patients with type 2 diabetes mellitus, is increasing, and as a result there is growing interest in using hard end-point data of this type in economic analyses. This study investigated published approaches for modeling hard end-points from clinical trials and evaluated their applicability in health economic models with different disease features.

METHODS

A review of cost-effectiveness models of interventions in clinically significant therapeutic areas (CV diseases, cancer, and chronic lower respiratory diseases) was conducted in PubMed and Embase using a defined search strategy. Only studies integrating hard end-point data from randomized clinical trials were considered. For each study included, clinical input characteristics and modeling approach were summarized and evaluated.

RESULTS

A total of 33 articles (23 CV, eight cancer, two respiratory) were accepted for detailed analysis. Decision trees, Markov models, discrete event simulations, and hybrids were used. Event rates were incorporated either as constant rates, time-dependent risks, or risk equations based on patient characteristics. Risks dependent on time and/or patient characteristics were used where major event rates were >1%/year in models with fewer health states (<7). Models of infrequent events or with numerous health states generally preferred constant event rates.

LIMITATIONS

The detailed modeling information and terminology varied, sometimes requiring interpretation.

CONCLUSIONS

Key considerations for cost-effectiveness models incorporating hard end-point data include the frequency and characteristics of the relevant clinical events and how the trial data is reported. When event risk is low, simplification of both the model structure and event rate modeling is recommended. When event risk is common, such as in high risk populations, more detailed modeling approaches, including individual simulations or explicitly time-dependent event rates, are more appropriate to accurately reflect the trial data.

Antiplatelet therapy in patients undergoing percutaneous coronary intervention: economic considerations

Percutaneous coronary intervention (PCI) is one of the most common medical procedures performed for treatment of coronary artery disease. Antiplatelet medications as adjunctive therapy for PCI are used routinely, with indications for specific agents or their combinations varying depending on the clinical scenario. While the cost-effectiveness of well-established agents has been extensively studied, newer drugs have not been evaluated as thoroughly. In addition, the clinical application of some antiplatelet drugs has recently changed, thus making older studies of cost effectiveness less applicable to the current landscape of clinical practice. This article reviews cost-effectiveness considerations of antiplatelet therapies in the treatment of coronary artery disease in patients undergoing PCI. Aspirin, P2Y12 inhibitors including clopidogrel and the newer agents prasugrel and ticagrelor, as well as glycoprotein (GP) IIb/IIIa inhibitors, are discussed. Overall, the use of dual antiplatelet therapy with aspirin and a P2Y12 inhibitor in patients undergoing PCI improves ischaemic outcomes and appears to be cost effective. The few available studies suggest that the recently approved medications prasugrel and ticagrelor are cost-effective alternatives to clopidogrel. However, no direct comparison between these two newer agents is available. The indications for GP IIb/IIIa inhibitors have changed in the current PCI era, and there is a paucity of cost-effectiveness data for their use in contemporary care.

Clopidogrel versus aspirin in patients with atherothrombosis: a CAPRIE-based cost-effectiveness model for Greece

BACKGROUND

Atherothrombosis represents a leading cause of morbidity and mortality worldwide. Given the prominent role of platelet aggregation in atherothrombosis, antiplatelet therapy forms the cornerstone of treatment, with proven efficacy in the secondary prevention of atherothrombotic events. Although clopidogrel seems to be superior to aspirin in terms of risk reduction for an atherothrombotic event, whether this clinical advantage is cost effective in Greece is unknown.

OBJECTIVE

The aim of this study was to conduct a cost-effectiveness analysis comparing clopidogrel with aspirin in the secondary prevention of atherothrombotic events in patients with peripheral artery disease, a recent stroke or a recent myocardial infarction, from the third-party-payer perspective in Greece.

METHODS

A Markov model with a 6-month cycle length was developed. Transition probabilities used in the model were obtained from the event rates reported in the CAPRIE trial. The effect of clopidogrel was applied only during the first 2 years of the model. Utility data were used to estimate quality-adjusted life-years (QALYs). Costs (for the year 2012) assigned to each health state included antiplatelet treatment cost, cost for the management of adverse events related to antiplatelet therapy and the direct healthcare cost of patients (i.e. concomitant medication, hospitalization, outpatient visits, rehabilitation, laboratory and imaging diagnostic examinations as well as interventions) in the acute and follow-up phase, separately. The incremental cost-effectiveness ratio (ICER) was calculated for life-years (LYs) and QALYs, separately. A probabilistic sensitivity analysis was conducted in order to evaluate the impact of the variation that characterizes the majority of model parameters to the cost-effectiveness results.

RESULTS

The Markov analysis revealed that the discounted survival was 11.83 (95% CI 11.40, 12.22) years and 12.17 (95% CI 11.75, 12.55) years in the aspirin and clopidogrel treatment groups, respectively, a difference of 0.34 (95% CI 0.09, 0.618) LYs. The corresponding discounted QALYs were 8.63 (95% CI 8.34, 8.90) and 8.84 (95% CI 8.54, 9.10), respectively, a difference of 0.21 (95% CI 0.05, 0.37) QALYs. The cumulated lifetime costs per patient were €20 678 (95% CI 19 675, 21 724) and €21 688 (95% CI 20 649, 22 773), for aspirin and clopidogrel treatment arm, respectively. The ICER for clopidogrel was calculated to be €4038 (95% CI 2743, 7837) for each LY saved and €5518 (95% CI 3358, 12 921) for each QALY saved.

CONCLUSION

The analysis indicates that clopidogrel is cost effective for the secondary prevention of atherothrombotic events in the Greek setting. These findings are in line with those reported in other European countries.

Cost of clinical events in health economic evaluations in Germany: a systematic review

Guidance from the Institute for Quality and Efficiency in Health Care (IQWiG) on cost estimation in cost-benefit assessments in Germany acknowledges the need for standardization of costing methodology. The objective of this review was to assess current methods for deriving clinical event costs in German economic evaluations. A systematic literature search of 24 databases (including MEDLINE, BIOSIS, the Cochrane Library and Embase) identified articles, published between January 2005 and October 2009, which reported cost-effectiveness or cost-utility analyses. Studies assessed German patients and evaluated at least one of 11 predefined clinical events relevant to patients with diabetes mellitus. A total of 21 articles, describing 199 clinical cost events, met the inclusion criteria. Year of costing and time horizon were available for 194 (97%) and 163 (82%) cost events, respectively. Cost components were rarely specified (32 [16%]). Costs were generally based on a single literature source (140 [70%]); where multiple sources were cited (32 [16%]), data synthesis methodology was not reported. Cost ranges for common events, assessed using a Markov model with a cycle length of 12 months, were: acute myocardial infarction (nine studies), first year, 4,618-17,556 €; follow-up years, 1,006-3,647 €; and stroke (10 studies), first year; 10,149-24,936 €; follow-up years, 676-7,337 €. These results demonstrate that costs for individual clinical events vary substantially in German health economic evaluations, and that there is a lack of transparency and consistency in the methods used to derive them. The validity and comparability of economic evaluations would be improved by guidance on standardizing costing methodology for individual clinical events.

Cost-effectiveness analysis of short-term clopidogrel therapy for ST elevation myocardial infarction

Clopidogrel improves outcomes in patients with ST-segment elevation myocardial infarction (STEMI) and is recommended in the guidelines. We sought to determine the incremental cost-effectiveness of clopidogrel therapy in this patient population. We used primary patient-level resource use and clinical outcomes data from 3491 STEMI patients treated with fibrinolysis and either clopidogrel or placebo prior to a diagnostic coronary angiogram in the Clopidogrel as Adjunctive Reperfusion Therapy-Thrombolysis in Myocardial Infarction 28 (CLARITY-TIMI 28) trial. Costs for each patient were calculated based on diagnosis-related groups-specific Medicare reimbursement rates for all hospitalizations and the average wholesale price of clopidogrel. Cost per event prevented and cost per life year gained (LYG) were calculated using standard methods. The estimate of LYG due to clopidogrel therapy was based on recurrent myocardial infarction and death outcomes. The bootstrap method was used to produce bias-corrected confidence intervals for cost and efficacy estimates as well as the cost per LYG ratio. Total costs and resource use were not significantly different for the clopidogrel and placebo groups ($8128 vs. $8134), indicating that short-term clopidogrel therapy is an economically dominant treatment strategy. Even in a sensitivity analysis accounting for higher long-term medical costs due to greater life expectancy, clopidogrel remained under $6000 per LYG. Clopidogrel therapy was dominant in 35% of the bootstrap simulations and cost less than $50,000 per LYG in 67% of simulations. In conclusion, this analysis finds short-term clopidogrel therapy to be a highly economically attractive therapy, improving patient outcomes at no increase in costs.

Cost-effectiveness of clopidogrel in STEMI patients in the Netherlands: a model based on the CLARITY trial

OBJECTIVE

This study assesses the costs and effects of combination treatment with clopidogrel and aspirin in comparison to aspirin alone in patients with an ST-segment elevation myocardial infarction (STEMI) in a Dutch setting.

METHODS

A decision tree model is used to combine data from different sources about efficacy, epidemiology and costs. In the short-run, cost-effectiveness is based on efficacy data derived from the CLARITY trial. The cost-effectiveness of continued treatment is addressed by analysing which conditions need to be fulfilled to deem the strategy 'cost-effective', and discussing whether it is likely that it is. Estimates concerning the benefits of preventing events are derived from Swedish registries. Approximations of both direct and indirect costs are derived from the literature. Effects are expressed as life years gained and Quality Adjust Life Years (QALYs). Uncertainties are addressed by uni- and multivariate sensitivity analyses with and without taking account of the dependency between the separate ischaemic events.

RESULTS

A treatment regimen similar to that of the CLARITY trial, including patients similar to those in the trial, is estimated to result in 0.05 additional life years and 0.062 additional quality adjusted life years for a cost that is euro1929 lower than aspirin therapy. Continuation of treatment outside the trial period is expected to result in ICERs of below euro20,000 per QALY as long as the real risk reduction of combination treatment is greater than 0.487% per year.

CONCLUSION

The results indicate that clopidogrel therapy combined with aspirin, according to the regimen seen in CLARITY, and using data from Swedish registries to inform the model, is cost-effective. Sensitivity analyses suggest that the model is robust to a wide range of parameter estimates, including those based on data from Swedish registries. Continued treatment is very likely to be cost effective in light of all the indirect evidence.

Costs and consequences of clopidogrel versus aspirin for secondary prevention of ischaemic events in (high-risk) atherosclerotic patients in Sweden: a lifetime model based on the CAPRIE trial and high-risk CAPRIE subpopulations

BACKGROUND

Antiplatelet therapy plays a central role in the prevention of atherothrombotic events. Both acetylsalicylic acid (aspirin) and clopidogrel have been shown to reduce the risk of recurrent cardiovascular events in various subgroups of patients with vascular disease.

OBJECTIVE

To estimate the cost effectiveness of clopidogrel versus aspirin in Sweden for the prevention of atherothrombotic events based on CAPRIE trial data. The focus of this study is on two high-risk subpopulations: (i) patients with pre-existing symptomatic atherosclerotic disease; and (ii) patients with polyvascular disease.

METHODS

A Markov model combining clinical, epidemiological and cost data was used to assess the economic value of clopidogrel compared with aspirin during a patient's lifetime. A societal perspective was used, with costs stated in Swedish kronor (SEK), year 2007 values. For the first 2 years, the clinical input for the model was based on the relevant subpopulations in the CAPRIE trial. Thereafter, transition probabilities were extrapolated, taking account of increased risks related to age and to a history of events. Cost effectiveness of 2 years of therapy is presented as cost per life-year gained (LYG) and as cost per QALY. Univariate and multivariate sensitivity analyses were performed to investigate robustness of results.

RESULTS

For patients resembling the total CAPRIE population, who were treated with clopidogrel, the expected cost per LYG was SEK217,806 and the cost per QALY was estimated at SEK169,154. For the high-risk CAPRIE subpopulations, costs per QALY were lowest for patients with pre-existing symptomatic atherosclerotic disease (SEK38,153). Using a 'willingness-to-pay' perspective indicated that treatment with clopidogrel instead of aspirin in high-risk patients is associated with a high probability for cost effectiveness; 81% using a threshold of SEK100,000 per QALY and 98% using a threshold of SEK500,000 per QALY. Overall, the results appeared to be robust over the sensitivity analyses performed.

CONCLUSION

When considering the cost-effectiveness categorization as proposed by the Swedish National Board of Health and Welfare, clopidogrel appears to be associated with costs per QALY that range from intermediate in the total CAPRIE population to low in high-risk atherosclerotic patients.

Adherence to guidelines for sensitivity analysis: cost-effectiveness analyses of dual oral antiplatelet therapy

OBJECTIVE

Cost-effectiveness analyses of new treatments for cardiovascular disease frequently require input parameters whose values are known with uncertainty due to limited data. The objective of this paper is to examine the extent to which published sensitivity analyses addressing this uncertainty adhere to Health Technology Assessment (HTA) guidelines.

RESEARCH DESIGN AND METHODS

A systematic review of published cost-effectiveness analyses was performed for an example drug treatment scenario, dual oral antiplatelet therapy compared with aspirin alone following acute coronary syndromes and/or percutaneous coronary intervention. The following medical literature databases were searched for articles published from January 1997 to June 2007: PubMed, Cochrane Collaboration, EMBASE and the Health Economic Evaluation Database (HEED). Evidence tables were created to show the sensitivity of the cost-effectiveness estimates to changes in the input parameter values, as well as the data sources used for the reference-case and sensitivity analysis input parameter values. The extent to which the sensitivity analyses adhered to HTA guidelines were also examined.

RESULTS

Cost-effectiveness ratios were most sensitive to changes in the efficacy of dual antiplatelet therapy and reference-case model assumptions about costs beyond the trial period. Although alternative values tested in the sensitivity analysis for some input parameters were based on observed ranges or distributions, alternative values tested for many other input parameters were assumed without justification.

CONCLUSIONS

Sensitivity analyses in the cost-effectiveness studies of dual oral antiplatelet therapy were not fully adherent with HTA guidelines. In particular, long-term costs and benefits were not always included in the sensitivity estimates, the impact of differential effects on death and myocardial infarction was not explored, and justification for the alternative parameter values tested was not always provided.

Cost-effectiveness of clopidogrel: seeing through the smoke

BACKGROUND

The authors reviewed various recommendations and practices for cost-effectiveness analysis. They also performed a PubMed search for clopidogrel and cost-effectiveness from 2004 to early 2008 to obtain original analyses published in English to look for possible associations of assumptions and conclusions with reported pharmaceutical support.

RESULTS

. Inclusion of incident cases and truncation at a sensible follow-up time more appropriately reflect the burden to be assumed by third-party payers. Extending the time horizon too far runs the risk of decreasing any relation with future reality. Parsimony cannot justify simplifications that omit relevant issues such as noncoronary costs, which worsen the calculated cost-effectiveness ratio of clopidogrel by 5% to 27%. The choice of the population to be analyzed has a major effect on cost-effectiveness: pharmaceutically sponsored studies published between 2004 and early 2008 focused on high-risk patients and have routinely shown more favorable cost-effectiveness ratios for clopidogrel than studies without pharmaceutical support.

CONCLUSION

. Any entity hoping to make the cost-effectiveness ratio of clopidogrel look more favorable would prefer the isolated, cohort approach and limit the analysis to high-risk patients most likely to benefit from it. This approach ignores the reality of medical policies and does not address the most relevant questions regarding the optimum use of clopidogrel.