Clopidogrel versus aspirin for secondary prophylaxis of vascular events: a cost-effectiveness analysis

Monotherapy with P2Y12-inhibitors after dual antiplatelet therapy: Filling gaps in evidence

BACKGROUND

Whether P2Y12 inhibitor monotherapy (P2Y12-I) is superior to aspirin following DAPT discontinuation post-PCI remains to be established.

METHODS

We updated our prior network meta-analysis where P2Y12-I and aspirin had been compared with DAPT or directly with each other. The focus is specifically on the available direct evidence, now consisting of the three head-to-head comparisons of P2Y12-I and aspirin in event-free PCI patients after DAPT. We include a Trial Sequential Analysis of the direct evidence based on meta-analytical literature.

RESULTS

The main finding reveals a 39% significantly lower risk of myocardial infarction with P2Y12-I (RR 0.61, 95% CI 0.47-0.78, p = 0.0001, I2 = 0%) with no difference in bleeding. Trial Sequential Analysis demonstrates clinically meaningful evidence for a reduction in the incidence of myocardial infarction with P2Y12-I that is also supported by statistical significance.

CONCLUSIONS

Accruing data highlight that P2Y12-I following DAPT discontinuation after PCI is associated with lower risk for MI and a similar risk for bleeding as compared with ASA. In light of potential limitations to the widespread adoption of life-long P2Y12-I treatment, clinicians should consider identifying selected patients who are expected to derive the highest benefit.

Bleeding risk in patients prescribed dual antiplatelet therapy and triple therapy after coronary interventions: the ADAPTT retrospective population-based cohort studies

Background

Bleeding among populations undergoing percutaneous coronary intervention or coronary artery bypass grafting and among conservatively managed patients with acute coronary syndrome exposed to different dual antiplatelet therapy and triple therapy (i.e. dual antiplatelet therapy plus an anticoagulant) has not been previously quantified.

Objectives

The objectives were to estimate hazard ratios for bleeding for different antiplatelet and triple therapy regimens, estimate resources and the associated costs of treating bleeding events, and to extend existing economic models of the cost-effectiveness of dual antiplatelet therapy.

Design

The study was designed as three retrospective population-based cohort studies emulating target randomised controlled trials.

Setting

The study was set in primary and secondary care in England from 2010 to 2017.

Participants

Participants were patients aged ≥ 18 years undergoing coronary artery bypass grafting or emergency percutaneous coronary intervention (for acute coronary syndrome), or conservatively managed patients with acute coronary syndrome.

Data sources

Data were sourced from linked Clinical Practice Research Datalink and Hospital Episode Statistics.

Interventions

Coronary artery bypass grafting and conservatively managed acute coronary syndrome: aspirin (reference) compared with aspirin and clopidogrel. Percutaneous coronary intervention: aspirin and clopidogrel (reference) compared with aspirin and prasugrel (ST elevation myocardial infarction only) or aspirin and ticagrelor.

Main outcome measures

Primary outcome: any bleeding events up to 12 months after the index event. Secondary outcomes: major or minor bleeding, all-cause and cardiovascular mortality, mortality from bleeding, myocardial infarction, stroke, additional coronary intervention and major adverse cardiovascular events.

Results

The incidence of any bleeding was 5% among coronary artery bypass graft patients, 10% among conservatively managed acute coronary syndrome patients and 9% among emergency percutaneous coronary intervention patients, compared with 18% among patients prescribed triple therapy. Among coronary artery bypass grafting and conservatively managed acute coronary syndrome patients, dual antiplatelet therapy, compared with aspirin, increased the hazards of any bleeding (coronary artery bypass grafting: hazard ratio 1.43, 95% confidence interval 1.21 to 1.69; conservatively-managed acute coronary syndrome: hazard ratio 1.72, 95% confidence interval 1.15 to 2.57) and major adverse cardiovascular events (coronary artery bypass grafting: hazard ratio 2.06, 95% confidence interval 1.23 to 3.46; conservatively-managed acute coronary syndrome: hazard ratio 1.57, 95% confidence interval 1.38 to 1.78). Among emergency percutaneous coronary intervention patients, dual antiplatelet therapy with ticagrelor, compared with dual antiplatelet therapy with clopidogrel, increased the hazard of any bleeding (hazard ratio 1.47, 95% confidence interval 1.19 to 1.82), but did not reduce the incidence of major adverse cardiovascular events (hazard ratio 1.06, 95% confidence interval 0.89 to 1.27). Among ST elevation myocardial infarction percutaneous coronary intervention patients, dual antiplatelet therapy with prasugrel, compared with dual antiplatelet therapy with clopidogrel, increased the hazard of any bleeding (hazard ratio 1.48, 95% confidence interval 1.02 to 2.12), but did not reduce the incidence of major adverse cardiovascular events (hazard ratio 1.10, 95% confidence interval 0.80 to 1.51). Health-care costs in the first year did not differ between dual antiplatelet therapy with clopidogrel and aspirin monotherapy among either coronary artery bypass grafting patients (mean difference £94, 95% confidence interval -£155 to £763) or conservatively managed acute coronary syndrome patients (mean difference £610, 95% confidence interval -£626 to £1516), but among emergency percutaneous coronary intervention patients were higher for those receiving dual antiplatelet therapy with ticagrelor than for those receiving dual antiplatelet therapy with clopidogrel, although for only patients on concurrent proton pump inhibitors (mean difference £1145, 95% confidence interval £269 to £2195).

Conclusions

This study suggests that more potent dual antiplatelet therapy may increase the risk of bleeding without reducing the incidence of major adverse cardiovascular events. These results should be carefully considered by clinicians and decision-makers alongside randomised controlled trial evidence when making recommendations about dual antiplatelet therapy.

Limitations

The estimates for bleeding and major adverse cardiovascular events may be biased from unmeasured confounding and the exclusion of an eligible subgroup of patients who could not be assigned an intervention. Because of these limitations, a formal cost-effectiveness analysis could not be conducted.

Future work

Future work should explore the feasibility of using other UK data sets of routinely collected data, less susceptible to bias, to estimate the benefit and harm of antiplatelet interventions.

Trial registration

This trial is registered as ISRCTN76607611.

Funding

This project was funded by the National Institute for Health and Care Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 27, No. 8. See the NIHR Journals Library website for further project information.

Cost-effectiveness of Screening for Paroxysmal Atrial Fibrillation in Patients undergoing Echocardiography

OBJECTIVE

To compare the cost-effectiveness of unselected electrocardiographic (ECG) screening for atrial fibrillation (AF), and selective screening based on an abnormal echocardiogram.

METHODS

Two strategies of portable ECG screening for AF were compared in the base case of a hypothetical asymptomatic 65-year-old man (CHA₂ DS₂ -VASC=3 based on hypertension and diabetes mellitus) with previous echocardiography but without a cause for AF (eg. mitral valve disease, LV dysfunction). With age-based screening (AgeScreen, 3% AF detection rate) all patients underwent ECG. With imaging-guided screening (ImagingScreen; 5% detection rate), only patients with left atrial volume (LA) ≥34ml/m² and LA reservoir strain <34% or LV global longitudinal strain (GLS)>-18% underwent ECG screening. A Markov model was informed by published transition probabilities, costs and quality-adjusted life years (QALY). Costs, effects and incremental cost-effectiveness ratio (ICER) were assessed for each screening strategy over a 20 year period. The willingness-to-pay threshold was $53,000/QALY.

RESULTS

ImagingScreen dominated AgeScreen, with a lower cost ($54,823 vs $57,842) and better outcome (11.56 vs 11.52 QALY over 20 years). Monte Carlo simulation demonstrated that 61% of observations were more efficacious with ImagingScreen, with cost below willingness-to-pay. The main cost determinants were annual costs of stroke or heart failure and AF detection rates. ImagingScreen was more cost-effective for AF detection rates up to 14%, and more cost-effective across a range of annual stroke ($24,000-$102,000) and heart failure ($4,000-$12,000) costs.

CONCLUSION

In patients with a previous echocardiogram, AF screening of those with baseline clinical and imaging risk parameters is more cost-effective than age-based screening. This article is protected by copyright. All rights reserved.

Economic Evaluation of Ticagrelor Plus Aspirin Versus Aspirin Alone for Acute Ischemic Stroke and Transient Ischemic Attack

Background: Although ticagrelor plus aspirin is more effective than aspirin alone in preventing the 30-day risk of a composite of stroke or death in patients with an acute mild-to-moderate ischemic stroke (IS) or transient ischemic attack (TIA), the cost-effectiveness of this combination therapy remains unknown. This study aims to determine the cost-effectiveness of ticagrelor plus aspirin compared with aspirin alone.

Methods: A combination of decision tree and Markov model was built to estimate the expected costs and quality-adjusted life-years (QALYs) associated with ticagrelor plus aspirin and aspirin alone in the treatment of patients with an acute mild-to-moderate IS or TIA. Model inputs were extracted from published sources. One-way sensitivity, probabilistic sensitivity, and subgroup analyses were performed to test the robustness of the findings.

Results: Compared with aspirin alone, ticagrelor plus aspirin gained an additional lifetime QALY of 0.018 at an additional cost of the Chinese Yuan Renminbi (¥) of 269, yielding an incremental cost-effectiveness ratio of ¥15,006 (US$2,207)/QALY. Probabilistic sensitivity analysis showed that ticagrelor plus aspirin had a probability of 99.99% being highly cost-effective versus aspirin alone at the current willingness-to-pay threshold of ¥72,447 (US$10,500)/QALY in China. These findings remain robust under one-way sensitivity and subgroup analyses.

Conclusions: The results indicated that early treatment with a 30-days ticagrelor plus aspirin for an acute mild-to-moderate IS or TIA is highly cost-effective in a Chinese setting.

Peripheral Artery Disease: A comprehensive updated review

Peripheral arterial disease is estimated to affect more than 200 million people worldwide. Although more than 50% of those affected are asymptomatic, it accounts for 3-4% of amputations and a crude five-year death rate of 82.4 deaths per 1000 patient-years when adjusted for duration of follow-up. Additionally, peripheral artery disease is often an indicator of obstructive atherosclerotic disease involvement of cerebral and coronary vessels, consequently increasing the risk of stroke, cardiovascular death, and myocardial infarction in these patient populations. The management of peripheral arterial disease includes conservative therapies, pharmacological treatments, interventional and surgical revascularization of blood vessels. Percutaneous transluminal angioplasty with balloons and stents has improved clinical outcomes compared to medical treatment alone. Despite these advances, the prevalence of peripheral arterial disease remains high. This review article aims to provide focused, up-to-date information on the clinical course, diagnosis, medical and interventional approach of the management of peripheral artery disease.

Cost-utility of ticagrelor plus aspirin in diabetic patients with stable coronary artery disease

AIMS

Ticagrelor plus aspirin could reduce the risks of major adverse cardiac events in diabetic patients with stable coronary artery disease (SCD), and yet it also increases bleeding risk. This study would compare the cost and effectiveness of aspirin and ticagrelor plus aspirin therapies in diabetic patients with SCD from a US healthcare sector perspective.

METHODS AND RESULTS

A state-transition Markov model was developed to project probabilities of myocardial infarction, ischaemic stroke, bleeding, and death with and without ticagrelor among all diabetic patients with SCD as the overall population, and those with a history of previous percutaneous coronary intervention (PCI) as a sub-population. Model inputs were extracted from published sources. Lifetime costs and quality-adjusted life-years (QALYs) were measured. The clinical benefits and bleeding risk of ticagrelor added to aspirin were translated into additional 0.08 QALYs at incremental costs of $19 580 in the overall population, yielding an incremental cost-utility ratio (ICUR) of $260 032/QALY. In the sub-population with an additional 0.43 QALYs at an incremental cost of $20 189, the ICUR was $46 426/QALY. Two-way sensitivity showed the clinical benefits of ticagrelor plus aspirin was counterbalanced by its risk of major bleeding. One-way sensitivity and probabilistic sensitivity analysis demonstrated that the results were generally robust except the all-cause death reduction.

CONCLUSION

The results indicated that ticagrelor plus aspirin is likely to be a cost-effective option in the diabetic patients with a history of PCI. Diabetes management can be improved by carefully prescribing ticagrelor to individuals with low risk of bleeding and high risk of ischaemic events.

Cost-Effectiveness and Cost-Utility Analysis of the Use of Clopidogrel and Pantoprazole in Comparison with Clopidogrel and Omeprazole for the Secondary Prevention of Myocardial Infarction in Iran

Objective:

Gastrointestinal bleeding, a side effect of clopidogrel, is usually prevented by proton-pump inhibitors (PPIs). Due to omeprazole's inhibitory effects on the liver enzyme CYP2C19, its concomitant use with clopidogrel is argued to increase the risk of myocardial infarction (MI) recurrence, as CYP2C19 activates clopidogrel. Pantoprazole as an alternative PPI has shown no inhibitory effect on CYP2C19. This study investigates the cost-effectiveness of concomitant use of clopidogrel and pantoprazole in MI patients compared to the simultaneous use of clopidogrel and omeprazole.

Methods:

We used the Markov-modeling technique with a hypothetical cohort of 1000 acute MI patients aged 55 years using Microsoft Excel 2013 software. The study was done from the payer perspective, and a lifetime horizon with 1-year cycles was considered in the model. Life-years gained (LYG) and quality-adjusted life-years (QALYs) were used to quantify the health effects of these interventions. Two separate scenarios of public tariffs and private tariffs with various discount rates (0%, 3%, and 7.2% discounts (only for costs)) were evaluated, and an incremental cost-effectiveness ratio (ICER) was used to report the results. One-way and probabilistic sensitivity analyses were used to deal with uncertainty. Data were sourced from published literature and tariff book of the Iranian ministry of health.

Findings:

The estimated ICERs were 342 USD/QALY and 236 USD/LYG per patient for the base-case scenario.

Conclusion:

Abiding by the WHO threshold for cost-effectiveness, the concomitant use of pantoprazole and clopidogrel can be considered cost-effective compared to the use of omeprazole and clopidogrel.

Cost-effectiveness of CYP2C19-guided antiplatelet therapy in patients with acute coronary syndrome and percutaneous coronary intervention informed by real-world data

Current guidelines recommend dual antiplatelet therapy (DAPT) consisting of aspirin and a P2Y12 inhibitors following percutaneous coronary intervention (PCI). CYP2C19 genotype can guide DAPT selection, prescribing ticagrelor or prasugrel for loss-of-function (LOF) allele carriers (genotype-guided escalation). Cost-effectiveness analyses (CEA) are traditionally grounded in clinical trial data. We conduct a CEA using real-world data using a 1-year decision-analytic model comparing primary strategies: universal empiric clopidogrel (base case), universal ticagrelor, and genotype-guided escalation. We also explore secondary strategies commonly implemented in practice, wherein all patients are prescribed ticagrelor for 30 days post PCI. After 30 days, all patients are switched to clopidogrel irrespective of genotype (nonguided de-escalation) or to clopidogrel only if patients do not harbor an LOF allele (genotype-guided de-escalation). Compared with universal clopidogrel, both universal ticagrelor and genotype-guided escalation were superior with improvement in quality-adjusted life years (QALY's). Only genotype-guided escalation was cost-effective ($42,365/QALY) and demonstrated the highest probability of being cost-effective across conventional willingness-to-pay thresholds. In the secondary analysis, compared with the nonguided de-escalation strategy, although genotype-guided de-escalation and universal ticagrelor were more effective, with ICER of $188,680/QALY and $678,215/QALY, respectively, they were not cost-effective. CYP2C19 genotype-guided antiplatelet prescribing is cost-effective compared with either universal clopidogrel or universal ticagrelor using real-world implementation data. The secondary analysis suggests genotype-guided and nonguided de-escalation may be viable strategies, needing further evaluation.

Cost-Effectiveness of a Multifaceted Quality Improvement Intervention for Acute Ischemic Stroke in China

Background and Purpose- Multifaceted quality improvement interventions of stroke care have been shown to improve hospital personnel adherence to evidence-based performance measures and subsequent stroke outcomes. This study aimed to evaluate the cost-effectiveness of a multifaceted quality improvement intervention for stroke care in China, the world's largest low- and middle-income country. Methods- A short-term decision tree model and a long-term Markov model were used to analyze the cost-effectiveness of a multifaceted quality improvement intervention for patients with acute ischemic stroke. Outcomes, transition probability, and cost data were obtained from a recent clinical trial and the published literature. The benefit of the intervention was assessed by the costs per quality-adjusted life-years gained in the short- and long-term. One-way and probabilistic sensitivity analyses were performed to assess the uncertainty of the findings. Results- Compared with usual care, a multifaceted quality improvement intervention for stroke care was found to be cost-effective in the first year and highly cost-effective from the second year onward. In the long-term, the intervention yielded a lifetime gain of 0.246 quality-adjusted life-years at an additional cost of Chinese Yuan Renminbi 1510 (US $230), resulting in a cost of Chinese Yuan Renminbi 6138 (US $940) per quality-adjusted life-year gained. Probabilistic sensitivity analysis indicated that the intervention was highly cost-effective in 99.9% of the simulation runs at a willingness-to-pay threshold of Chinese Yuan Renminbi 59 700 (1× gross domestic product per capita of China in 2017, US $9200) per quality-adjusted life-year. Conclusions- A multifaceted quality improvement intervention for stroke care was highly cost-effective in China. The results of this study may be used as a reference for delivering such interventions in low- and middle-income countries and in underserved areas of high-income countries.

Comparison Between Aspirin and Clopidogrel in Secondary Stroke Prevention Based on Real-World Data

Background

Clopidogrel was thought to be superior to aspirin for secondary prevention of vascular diseases in clinical trials. In this study we assessed the safety and efficacy of clopidogrel versus aspirin in real‐world practice by using the Taiwan Stroke Registry.

Methods and Results

Patients with ischemic stroke (2006–2016) on aspirin or clopidogrel for secondary stroke prevention were identified in the Taiwan Stroke Registry. Stroke recurrence and mortality rates in patients receiving aspirin (N=34 679) were compared with those receiving clopidogrel (N=7611) during a 12‐month follow‐up period. Propensity score matching and conditional Cox proportional hazards regression model were applied to control confounding factors with 6443 patients in each group. After propensity score matching, stroke recurrence rates were comparable between groups, with 223 patients in the aspirin (3.46%) and 244 in the clopidogrel group (3.79%) (hazard ratio=1.13, 95% confidence interval=0.89–1.43, P=0.311). However, the mortality rate was significantly higher in the clopidogrel group (362 patients, 5.62%) than in the aspirin group (302 patients, 4.69%) (hazard ratio=1.30, 95% confidence interval=1.07–1.58, P=0.008). Results were consistent before and after propensity score matching.

Conclusions

Clopidogrel was as effective as aspirin for prevention of recurrent stroke in real‐world practice. However, the mortality rate was significantly higher in the clopidogrel than in the aspirin group.

Cost-effectiveness of low-dose rivaroxaban and aspirin versus aspirin alone in people with peripheral or carotid artery disease: An Australian healthcare perspective

Aims

Peripheral artery disease affects 1.2% of the population globally and is associated with an increased risk of atherothrombotic cardiovascular events, major adverse limb events and mortality. The Cardiovascular Outcomes for People Using Anti-coagulation Strategies (COMPASS) trial demonstrated positive results of rivaroxaban plus aspirin therapy compared to aspirin therapy alone in those with peripheral artery disease or carotid artery disease. We sought to estimate the cost-effectiveness from the Australian healthcare system perspective.

Methods and results

A Markov model was developed to simulate the experiences of a hypothetical population of 1000 individuals with peripheral artery disease or carotid artery disease, profiled on the COMPASS trial, treated with rivaroxaban plus aspirin therapy versus aspirin therapy alone. With each annual cycle, individuals were at risk of having non-fatal cardiovascular disease events, major adverse limb events, or dying. Individuals were also at risk of non-fatal major bleeding. The model had a lifetime time horizon. Costs and utilities were sourced from the literature and discounted at 5.0% annually. Rivaroxaban plus aspirin therapy prevented 143 non-fatal cardiovascular disease events, 118 major adverse limb events and 10 deaths compared to aspirin therapy alone. Conversely, 156 additional major non-fatal bleeds were accrued. With an additional 256 quality-adjusted life years gained, at an additional cost of AUD$6,858,103, the incremental cost-effectiveness ratio was AUD$26,769 (discounted) per quality-adjusted life year gained, which is below Australia’s arbitrary willingness to pay threshold of AUD$50,000.

Conclusion

In those with peripheral artery disease or carotid artery disease, rivaroxaban plus aspirin therapy is effective and cost-effective in the prevention of recurrent cardiovascular disease compared to aspirin therapy alone.

Quality of health economic evaluations for the ACC/AHA stable ischemic heart disease practice guideline: A systematic review

BACKGROUND

The American College of Cardiology/American Heart Association (ACC/AHA) recently published a rigorous framework to guide integration of economic data into clinical guidelines. We assessed the quality of economic evaluations in a major ACC/AHA clinical guidance report.

METHODS

We systematically identified cost-effectiveness analyses (CEAs) of RCTs cited in the ACC/AHA 2012 Guideline for the Diagnosis and Management of Patients with Stable Ischemic Heart Disease. We extracted: (1) study identifiers; (2) parent RCT information; (3) economic analysis characteristics; and (4) study quality using the Quality of Health Economic Studies instrument (QHES).

RESULTS

Quality scores were categorized as high (≥75 points) or low (<75 points). Of 1,266 citations in the guideline, 219 were RCTs associated with 77 CEAs. Mean quality score was 81 (out of 100) and improved over time, though 29.9% of studies were low-quality. Cost-per-QALY was the most commonly reported primary outcome (39.0%). Low-quality studies were less likely to report study perspective, use appropriate time horizons, or address statistical and clinical uncertainty. Funding was overwhelmingly private (83%). A detailed methodological assessment of high-quality studies revealed domains of additional methodological issues not identified by the QHES.

CONCLUSIONS

Economic evaluations of RCTs in the 2012 ACC/AHA ischemic heart disease guideline largely had high QHES scores but methodological issues existed among "high-quality" studies. Because the ACC/AHA has generally been more systematic in its integration of scientific evidence compared to other professional societies, it is likely that most societies will need to proceed more cautiously in their integration of economic evidence.

Cost-effectiveness of mechanical thrombectomy within 6 hours of acute ischaemic stroke in China

OBJECTIVES

Endovascular mechanical thrombectomy is an effective but expensive therapy for acute ischaemic stroke with proximal anterior circulation occlusion. This study aimed to determine the cost-effectiveness of mechanical thrombectomy in China, which is the largest developing country.

DESIGN

A combination of decision tree and Markov model was developed. Outcome and cost data were derived from the published literature and claims database. The efficacy data were derived from the meta-analyses of nine trials. One-way and probabilistic sensitivity analyses were performed in order to assess the uncertainty of the results.

SETTING

Hospitals in China.

PARTICIPANTS

The patients with acute ischaemic stroke caused by proximal anterior circulation occlusion within 6 hours.

INTERVENTIONS

Mechanical thrombectomy within 6 hours with intravenous tissue plasminogen activator (tPA) treatment within 4.5 hours versus intravenous tPA treatment alone.

OUTCOME MEASURES

The benefit conferred by the treatment was assessed by estimating the cost per quality-adjusted life-year (QALY) gained in the long term (30 years).

RESULTS

The addition of mechanical thrombectomy to intravenous tPA treatment compared with standard treatment alone yielded a lifetime gain of 0.794 QALYs at an additional cost of CNY 50 000 (US$7700), resulting in a cost of CNY 63 010 (US$9690) per QALY gained. The probabilistic sensitivity analysis indicated that mechanical thrombectomy was cost-effective in 99.9% of the simulation runs at a willingness-to-pay threshold of CNY 125 700 (US$19 300) per QALY.

CONCLUSIONS

Mechanical thrombectomy for acute ischaemic stroke caused by proximal anterior circulation occlusion within 6 hours was cost-effective in China. The data may be used as a reference with regard to medical resources allocation for stroke treatment in low-income and middle-income countries as well as in the remote areas in the developed countries.

Cost-effectiveness evaluation of aspirin in primary prevention of myocardial infarction amongst males with average cardiovascular risk in Iran

Aspirin is one of the certified medicines commonly used for the secondary prevention of myocardial infarction (MI). Aspirin side effects and gastrointestinal bleeding, in particular, have arisen debates on its use for the primary prevention of MI. The present research evaluates the cost-effectiveness of the use of aspirin in the primary prevention of MI among Iranian men with average cardiovascular disease (CVD) risk, using Markov modeling technique. The incremental cost-effectiveness ratios (ICERs) estimated to be 864 USA dollars (USD) per quality-adjusted life years (QALY) gained and 782 USD per life years gained (LYG) for each patient in the base-case scenario (public tariffs and no discounting). This research proves cost-effectiveness of the use of aspirin in the primary prevention of MI in targeted population, since the assessed ICERs are quite under the recommended threshold by WHO which is one gross domestic product (GDP) per capita ($5315.1 for Iran in 2015).

Clopidogrel versus aspirin in patients with recent ischemic stroke and established peripheral artery disease: an economic evaluation in a Chinese setting

BACKGROUND AND OBJECTIVES

Clopidogrel or aspirin are indicated for patients with recent ischemic stroke (IS) or established peripheral artery disease (PAD). We compared the cost effectiveness of clopidogrel with that of aspirin in Chinese patients with recent IS or established PAD.

METHODS

A discrete-event simulation was developed to evaluate the economic implications of secondary prevention with clopidogrel versus aspirin. All available evidence was derived from clinical studies. Costs from a Chinese healthcare perspective in 2013 US dollars and quality-adjusted life-years (QALYs) were projected over patients' lifetimes. Uncertainties were addressed using sensitivity analyses.

RESULTS

Compared with aspirin, clopidogrel yielded a marginally increased life expectancy by 0.46 and 0.21 QALYs at an incremental cost-effectiveness ratio of $US5246 and $US9890 per QALY in patients with recent IS and established PAD, respectively. One-way sensitivity analyses showed that the evaluation of patients with PAD and recent IS was robust except for the parameter of patient age. Given a willingness-to-pay of $US19,877 per QALY gained, clopidogrel had a probability of 90 and 68% of being cost effective in the recent IS or established PAD subgroups compared with aspirin, respectively.

CONCLUSIONS

The analysis suggests that clopidogrel for secondary prevention is cost effective for patients with either PAD or recent IS in a Chinese setting in comparison with aspirin.

Novel synthetic benzimidazole-derived oligosaccharide, M3BIM, prevents ex vivo platelet aggregation and in vivo thromboembolism

Background

Thrombus formation, a phenomenon primarily related to increased platelet activation, plays a key role in cardiovascular and cerebrovascular diseases. Although the established antiplatelet agents, such as aspirin and clopidogrel, have been shown to be beneficial in treating thromboembolic diseases, they have considerable limitations. Hence, the development of more effective and safe antithrombotic agents is necessary to satisfy a substantial unmet clinical need. In recent years, the favorable properties of imidazole-related drugs have prompted medicinal chemists to synthesize numerous novel therapeutic agents. The chemical structure of the benzimidazole backbone has proven antiplatelet properties. Moreover, synthetic oligosaccharides have exhibited antiplatelet properties. Therefore, we developed a new aldo-benzimidazole-derived oligosaccharide compound, M3BIM, for achieving a stronger antiplatelet effect than the drugs which are being used in clinical aspects. We investigated the effects of M3BIM on platelet activation ex vivo and its antithrombotic activity in vivo.

Results

M3BIM (10–50 μM) exhibited a more potent activity in inhibiting platelet aggregation stimulated by collagen than it did in inhibiting that stimulated by thrombin in washed human platelets. The M3BIM treatment revealed no cytotoxicity in zebrafish embryos, even at the highest concentration of 100 μM. In addition, M3BIM inhibited the phosphorylation of phospholipase Cγ2, protein kinase C (PKC), and mitogen-activated protein kinases (MAPKs; extracellular signal-regulated kinase 2 and c-Jun N-terminal kinase 1), and markedly reduced the ATP-release reaction and intracellular calcium mobilization in collagen-activated platelets. By contrast, M3BIM showed no effects on either collagen-induced p38 MAPK and Akt phosphorylation or phorbol 12, 13-dibutyrate-induced PKC activation and platelet aggregation. Moreover, the M3BIM treatment substantially prolonged the closure time in human whole blood, and increased the occlusion time in mesenteric microvessels and attenuated cerebral infarction in mice. For the study of anticoagulant activities, M3BIM showed no significant effects in the prolongation of activated partial thromboplastin time and prothrombin time in mice.

Conclusion

The findings of our study suggest that M3BIM is a potential therapeutic agent for preventing or treating thromboembolic disorders.

Cost-effectiveness analysis alongside clinical trials II-An ISPOR Good Research Practices Task Force report

Clinical trials evaluating medicines, medical devices, and procedures now commonly assess the economic value of these interventions. The growing number of prospective clinical/economic trials reflects both widespread interest in economic information for new technologies and the regulatory and reimbursement requirements of many countries that now consider evidence of economic value along with clinical efficacy. As decision makers increasingly demand evidence of economic value for health care interventions, conducting high-quality economic analyses alongside clinical studies is desirable because they broaden the scope of information available on a particular intervention, and can efficiently provide timely information with high internal and, when designed and analyzed properly, reasonable external validity. In 2005, ISPOR published the Good Research Practices for Cost-Effectiveness Analysis Alongside Clinical Trials: The ISPOR RCT-CEA Task Force report. ISPOR initiated an update of the report in 2014 to include the methodological developments over the last 9 years. This report provides updated recommendations reflecting advances in several areas related to trial design, selecting data elements, database design and management, analysis, and reporting of results. Task force members note that trials should be designed to evaluate effectiveness (rather than efficacy) when possible, should include clinical outcome measures, and should obtain health resource use and health state utilities directly from study subjects. Collection of economic data should be fully integrated into the study. An incremental analysis should be conducted with an intention-to-treat approach, complemented by relevant subgroup analyses. Uncertainty should be characterized. Articles should adhere to established standards for reporting results of cost-effectiveness analyses. Economic studies alongside trials are complementary to other evaluations (e.g., modeling studies) as information for decision makers who consider evidence of economic value along with clinical efficacy when making resource allocation decisions.

Cost-effectiveness of clopidogrel-aspirin versus aspirin alone for acute transient ischemic attack and minor stroke

Background

Treatment with the combination of clopidogrel and aspirin taken soon after a transient ischemic attack (TIA) or minor stroke was shown to reduce the 90‐day risk of stroke in a large trial in China, but the cost‐effectiveness is unknown. This study sought to estimate the cost‐effectiveness of the clopidogrel‐aspirin regimen for acute TIA or minor stroke.

Methods and Results

A Markov model was created to determine the cost‐effectiveness of treatment of acute TIA or minor stroke patients with clopidogrel‐aspirin compared with aspirin alone. Inputs for the model were obtained from clinical trial data, claims databases, and the published literature. The main outcome measure was cost per quality‐adjusted life‐years (QALYs) gained. One‐way and multivariable probabilistic sensitivity analyses were performed to test the robustness of the findings. Compared with aspirin alone, clopidogrel‐aspirin resulted in a lifetime gain of 0.037 QALYs at an additional cost of CNY 1250 (US$ 192), yielding an incremental cost‐effectiveness ratio of CNY 33 800 (US$ 5200) per QALY gained. Probabilistic sensitivity analysis showed that clopidogrel‐aspirin therapy was more cost‐effective in 95.7% of the simulations at a willingness‐to‐pay threshold recommended by the World Health Organization of CNY 105 000 (US$ 16 200) per QALY.

Conclusions

Early 90‐day clopidogrel‐aspirin regimen for acute TIA or minor stroke is highly cost‐effective in China. Although clopidogrel is generic, Plavix is brand in China. If Plavix were generic, treatment with clopidogrel‐aspirin would have been cost saving.

Estimating the potential annual welfare impact of innovative drugs in use in Switzerland

Expenditures of health care systems are increasing from year to year. Therefore, this study aimed to estimate the difference in costs and benefits of innovative pharmaceuticals launched 2000 onward compared to standard treatment on the national economy of Switzerland in 2010. The approach and formula described in the pilot study by Tsiachristas et al. (1), which analyzed the situation of welfare effects in the Netherlands, served as a model for our own calculations. A literature search was performed to identify cost-utility or cost-effectiveness studies of drugs launched 2000 onward compared to standard treatment. All parameters required for the calculation of welfare effects were derived from these analyses. The base-case threshold value of a quality-adjusted life year was set to CHF 100,000. Overall, 31 drugs were included in the welfare calculations. The introduction of innovative pharmaceuticals since 2000 onward to the Swiss market led to a potential welfare gain of about CHF 781 million in the year 2010. Univariate sensitivity analysis showed that results were robust. Probably because of the higher benefits of new drugs on health and quality of life compared to standard treatment, these drugs are worth the higher costs. The literature search revealed that there is a lack of information about the effects of innovative pharmaceuticals on the overall economy of Switzerland. Our study showed that potential welfare gains in 2010 by introducing innovative pharmaceuticals to the Swiss market were substantial. Considering costs and benefits of new drugs is important.

Screen or not to screen for peripheral arterial disease: guidance from a decision model

Background

Asymptomatic Peripheral Arterial Disease (PAD) is associated with greater risk of acute cardiovascular events. This study aims to determine the cost-effectiveness of one time only PAD screening using Ankle Brachial Index (ABI) test and subsequent anti platelet preventive treatment (low dose aspirin or clopidogrel) in individuals at high risk for acute cardiovascular events compared to no screening and no treatment using decision analytic modelling.

Methods

A probabilistic Markov model was developed to evaluate the life time cost-effectiveness of the strategy of selective PAD screening and consequent preventive treatment compared to no screening and no preventive treatment. The analysis was conducted from the Dutch societal perspective and to address decision uncertainty, probabilistic sensitivity analysis was performed. Results were based on average values of 1000 Monte Carlo simulations and using discount rates of 1.5% and 4% for effects and costs respectively. One way sensitivity analyses were performed to identify the two most influential model parameters affecting model outputs. Then, a two way sensitivity analysis was conducted for combinations of values tested for these two most influential parameters.

Results

For the PAD screening strategy, life years and quality adjusted life years gained were 21.79 and 15.66 respectively at a lifetime cost of 26,548 Euros. Compared to no screening and treatment (20.69 life years, 15.58 Quality Adjusted Life Years, 28,052 Euros), these results indicate that PAD screening and treatment is a dominant strategy. The cost effectiveness acceptability curves show 88% probability of PAD screening being cost effective at the Willingness To Pay (WTP) threshold of 40000 Euros. In a scenario analysis using clopidogrel as an alternative anti-platelet drug, PAD screening strategy remained dominant.

Conclusion

This decision analysis suggests that targeted ABI screening and consequent secondary prevention of cardiovascular events using low dose aspirin or clopidogrel in the identified patients is a cost-effective strategy. Implementation of targeted PAD screening and subsequent treatment in primary care practices and in public health programs is likely to improve the societal health and to save health care costs by reducing catastrophic cardiovascular events.

Optimizing the use of aspirin for cardiovascular prevention

This article describes the mechanism of action, pharmacokinetics, and pharmacodynamics of aspirin at doses used for cardiovascular prevention and provides specific management recommendations for optimal use in clinical practice. The paper highlights practical aspects related to antiplatelet therapy, including the optimal dose of aspirin, concomitant treatment with other NSAIDs, and strategies for the prevention of gastrointestinal toxicity. Specifically, we revise the benefits and hazards in different clinical settings to help the clinician in the decision-making process for individuals who have different risks for cardiovascular and gastrointestinal bleeding events.

Sequential Value-of-Information Assessment for Prospective Drug Safety Monitoring Using Claims Databases

Background. Key to conducting active drug safety surveillance using longitudinal health care data is determining whether and when there is sufficient evidence to raise a safety alert. We propose to quantify the expected value of the information (VOI) to be gained through continued monitoring in terms of its potential to reduce health losses among future patients and weigh this against the health cost of exposing current patients during continued monitoring. Objective. To apply this sequential VOI approach to monitoring the comparative safety of prasugrel v. clopidogrel on gastrointestinal (GI) bleeding. Methods. We calculated expected health losses assuming expected mortality, nonfatal myocardial infarction (MI), and nonfatal stroke on clopidogrel were 1.27, 5.93, and 1.14 per 100 person-years, using historical data; relative rates on prasugrel were 0.95, 0.76, and 1.02 based on trial data; and MI, stroke, and GI bleed were 9%, 25%, and 0.1% as bad as death, respectively. We assigned gamma prior distributions to the rates of bleeding on clopidogrel and prasugrel to capture baseline uncertainty; in Monte Carlo simulations, prasugrel’s efficacy parameters were sampled from distributions. Results. Treating all patients with prasugrel minimized expected health losses, resulting in 475.3 death-equivalents over 25,000 person-years of treatment. Monitoring increased expected losses by 5, and treating all patients with clopidogrel increased losses by 46.4. In Monte Carlo simulation, monitoring on average increased expected losses by 4.6, but a reduction in losses from monitoring was supported within the bounds of uncertainty (95% confidence interval, −0.6 to 11.1). Limitations. Patient heterogeneity and the possibility of updating efficacy parameters during monitoring were not incorporated. Conclusion. The proposed approach integrates expected health harms and benefits of continued monitoring in the decision to raise a safety alert.

Impact of antiplatelet treatment on colorectal cancer staging characteristics

AIM: To evaluate whether antiplatelet medication leads to an earlier stage colorectal cancer (CRC) diagnosis.

METHODS: From January 2002 until March 2010, patients that presented to our institution with the initial diagnosis of CRC and were submitted to an open curative CRC resection or a palliative procedure were retrospectively reviewed. Exclusion criteria were the use of antithrombotic medication, i.e., coumarins, and appendiceal malignancies. Data acquired from medical files included age, gender, past medical history, antithrombotic treatment received prior to endoscopic diagnosis, preoperative imaging staging, location of the tumor, surgical and final histopathological report. Patients that did not receive any antithrombotic medication prior to the endoscopic diagnosis comprised the control group of the study, while patients that were on antiplatelet medication comprised the antiplatelet group. Primary end point was a comparison of CRC stage in the two groups of the study. CRC presenting symptoms and the incidence of each cancer stage in the two groups were also evaluated.

RESULTS: A total of 387 patients with the diagnosis of CRC were submitted to our department for further surgical treatment. Ninety-eight patients (25.32%), with a median age of 71 years (range 52-91 years), were included in the antiplatelet group, while 289 (74.67%) patients, with a median age of 67 years (range 41-90 years), were not in any thrombosis prophylaxis medication (control group). Thirty-one patients were treated with some kind of palliative procedure, either endoscopic, such as endoscopic stent placement, or surgical, such as de-compressive colostomy or deviation. Coronary disease (77.55% - 76 patients), stroke recurrence prevention (14.28% - 14 patients) and peripheral arterial disease (8.16% - 8 patients) were the indications for the administration of antiplatelet treatment (aspirin, clopidogrel, ticlopidine or dipyridamole) in the antiplatelet group. All patients on aspirin treatment received a dosage of 100 mg/d, while the minimum prophylactic dosages were also used for the rest of the antiplatelet drugs. Investigation of an iron deficiency anemia (147 patients), per rectum blood loss (84 patients), bowel obstruction and/or perforation (81 patients), bowel habits alterations (32 patients), non-specific symptoms, such as weight loss, intermittent abdominal pain and fatigue, (22 patients) or population screening (21 patients) were the indications for the endoscopic investigation in both groups. Bleeding, either chronic presenting as anemia or acute was significantly higher (P = 0.002) for the antiplatelet arm of the study (71 patients - 72.4% of the antiplatelet group vs 160 patients - 55.3% of the control group). The mean tumor, node and metastasis stage was 2.57 ± 0.96 for the control group, 2.27 ± 0.93 for the antiplatelet group (P = 0.007) and 2.19 ± 0.92 for the subgroup of patients taking aspirin (P = 0.003). The incidence of advanced disease (stage IV) was lower for the antiplatelet group of the study (P = 0.033).

CONCLUSION: The adverse effect of bleeding that is justifiably attached to this drug category seems to have a favorable impact on the staging characteristics of CRC.

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.

Oral antiplatelet therapy in the secondary prevention of atherothrombotic events

Atherothrombosis is the leading cause of death worldwide and has a large economic impact. It is a pathologic process related to atherosclerosis, which leads to adverse clinical manifestations, including acute coronary syndrome, cerebrovascular disease, and peripheral arterial disease. Patients with atherothrombosis are at heightened risk for recurrent ischemic events or death, and therefore, secondary prevention is an important goal in the treatment of these patients. Antiplatelet therapies available for long-term secondary prevention include aspirin (acetylsalicylic acid), extended-release dipyridamole plus aspirin, and clopidogrel. A number of clinical trials have demonstrated the benefit of combined antiplatelet therapy in secondary prevention, supporting the recommendations made in current published guidelines. Although the efficacy and safety of antiplatelet agents is well established and supported by clinical trials, their utilization rate in patients with atherothrombosis remains suboptimal. Quality improvement initiatives have demonstrated effectiveness in promoting the awareness and implementation of treatment guidelines. This article reviews the benefits and risks of antiplatelet therapy in patients with cardiovascular disease with the aim of spurring greater adherence to treatment recommendations and, thereby, better patient outcomes.

Correlation between prescribing quality and pharmaceutical costs in English primary care: national cross-sectional analysis

BACKGROUND

Both pharmaceutical costs and quality-indicator performance vary substantially between general practices, but little is known about the relationship between prescribing costs and quality.

AIM

To measure the association between prescribing quality and pharmaceutical costs among English general practices.

DESIGN AND SETTING

Cross-sectional observational study using data from the Quality and Outcomes Framework and the Prescribing Analysis and Cost database from all 8409 general practices in England in 2005-2006.

METHOD

Correlation between practice achievement of 26 prescribing quality indicators in eight prescribing areas and related pharmaceutical costs was examined.

RESULTS

There was no significant association between the overall achievement of quality indicators and related pharmaceutical costs (P= 0.399). Mean achievement of quality indicators across all eight prescribing areas was 79.0% (standard deviation 4.4%). There were small positive correlations in five prescribing areas: influenza vaccination, beta blockers, angiotensin converting enzyme inhibitors, lipid lowering, and antiplatelet treatment (all P<0.001). There were small negative correlations in two prescribing areas: hypertension (P<0.001) and smoking cessation (P = 0.018).

CONCLUSION

Correlations between prescribing quality and pharmaceutical costs were much smaller than expected; possible explanations for this include a substantial variation in rates of prescribing outside evidence-based protocols, and use of expensive pharmaceuticals instead of cheaper effective alternatives. There remains considerable scope for some practices to make pharmaceutical cost savings while improving quality performance. The ratio of quality scores to related pharmaceutical costs could be developed into a performance indicator.

Primary and secondary prevention of cardiovascular disease: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines

BACKGROUND

This guideline focuses on long-term administration of antithrombotic drugs designed for primary and secondary prevention of cardiovascular disease, including two new antiplatelet therapies.

METHODS

The methods of this guideline follow those described in Methodology for the Development of Antithrombotic Therapy and Prevention of Thrombosis Guidelines: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines in this supplement.

RESULTS

We present 23 recommendations for pertinent clinical questions. For primary prevention of cardiovascular disease, we suggest low-dose aspirin (75-100 mg/d) in patients aged > 50 years over no aspirin therapy (Grade 2B). For patients with established coronary artery disease, defined as patients 1-year post-acute coronary syndrome, with prior revascularization, coronary stenoses > 50% by coronary angiogram, and/or evidence for cardiac ischemia on diagnostic testing, we recommend long-term low-dose aspirin or clopidogrel (75 mg/d) (Grade 1A). For patients with acute coronary syndromes who undergo percutaneous coronary intervention (PCI) with stent placement, we recommend for the first year dual antiplatelet therapy with low-dose aspirin in combination with ticagrelor 90 mg bid, clopidogrel 75 mg/d, or prasugrel 10 mg/d over single antiplatelet therapy (Grade 1B). For patients undergoing elective PCI with stent placement, we recommend aspirin (75-325 mg/d) and clopidogrel for a minimum duration of 1 month (bare-metal stents) or 3 to 6 months (drug-eluting stents) (Grade 1A). We suggest continuing low-dose aspirin plus clopidogrel for 12 months for all stents (Grade 2C). Thereafter, we recommend single antiplatelet therapy over continuation of dual antiplatelet therapy (Grade 1B).

CONCLUSIONS

Recommendations continue to favor single antiplatelet therapy for patients with established coronary artery disease. For patients with acute coronary syndromes or undergoing elective PCI with stent placement, dual antiplatelet therapy for up to 1 year is warranted.

Antithrombotic and thrombolytic therapy for ischemic stroke: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines

OBJECTIVES

This article provides recommendations on the use of antithrombotic therapy in patients with stroke or transient ischemic attack (TIA).

METHODS

We generated treatment recommendations (Grade 1) and suggestions (Grade 2) based on high (A), moderate (B), and low (C) quality evidence.

RESULTS

In patients with acute ischemic stroke, we recommend IV recombinant tissue plasminogen activator (r-tPA) if treatment can be initiated within 3 h (Grade 1A) or 4.5 h (Grade 2C) of symptom onset; we suggest intraarterial r-tPA in patients ineligible for IV tPA if treatment can be initiated within 6 h (Grade 2C); we suggest against the use of mechanical thrombectomy (Grade 2C) although carefully selected patients may choose this intervention; and we recommend early aspirin therapy at a dose of 160 to 325 mg (Grade 1A). In patients with acute stroke and restricted mobility, we suggest the use of prophylactic-dose heparin or intermittent pneumatic compression devices (Grade 2B) and suggest against the use of elastic compression stockings (Grade 2B). In patients with a history of noncardioembolic ischemic stroke or TIA, we recommend long-term treatment with aspirin (75-100 mg once daily), clopidogrel (75 mg once daily), aspirin/extended release dipyridamole (25 mg/200 mg bid), or cilostazol (100 mg bid) over no antiplatelet therapy (Grade 1A), oral anticoagulants (Grade 1B), the combination of clopidogrel plus aspirin (Grade 1B), or triflusal (Grade 2B). Of the recommended antiplatelet regimens, we suggest clopidogrel or aspirin/extended-release dipyridamole over aspirin (Grade 2B) or cilostazol (Grade 2C). In patients with a history of stroke or TIA and atrial fibrillation we recommend oral anticoagulation over no antithrombotic therapy, aspirin, and combination therapy with aspirin and clopidogrel (Grade 1B).

CONCLUSIONS

These recommendations can help clinicians make evidence-based treatment decisions with their patients who have had strokes.

Antiplatelet and antithrombotic activities of timosaponin B-II, an extract of Anemarrhena asphodeloides

1. Antithrombotic agents are effective in the treatment of ischaemic stroke. Timosaponin B-II (TB-II) is a major active component of Anemarrhena asphodeloides Bunge (Liliaceae; rhizome) that has protective effects against cerebral ischaemic damage. The present study examined the antiplatelet and antithrombotic actions of TB-II. 2. In in vitro experiments, TB-II (20, 40 and 80 mg/mL) potently and dose-dependently inhibited ADP-induced platelet aggregation. Furthermore, 1, 3 and 6 mg/kg TB-II prolonged activated partial thromboplastin time by 9.29, 16.86 and 25.50%, respectively, but had no effect on the prothrombin time. Furthermore, 1, 3 and 6 mg/kg TB-II significantly reduced the wet weight, dry weight and length of the thrombi (%inhibition (based on wet weight): 13.6, 19.8 and 24.7%, respectively). 3. In a rabbit arteriovenous shunt model, 1, 3 and 6 mg/kg, i.v., TB-II had no effect on thrombus formation. Plasma euglobulin lysis time and fibrin degradation product were not affected by 1, 3 and 6 mg/kg TB-II, but plasminogen levels were decreased significantly by 14.4, 18.3 and 29.0%, respectively. 4. The results of the present study demonstrate significant antiplatelet and anticoagulation effects of TB-II and suggest that these actions could contribute to its neuroprotective effect against damage following cerebral ischaemia damage.

Potent antiplatelet activity of sesamol in an in vitro and in vivo model: pivotal roles of cyclic AMP and p38 mitogen-activated protein kinase

Sesamol is a potent phenolic antioxidant which possesses antimutagenic, antihepatotoxic and antiaging properties. Platelet activation is relevant to a variety of acute thrombotic events and coronary heart diseases. There have been few studies on the effect of sesamol on platelets. Therefore, the aim of this study was to systematically examine the detailed mechanisms of sesamol in preventing platelet activation in vitro and in vivo. Sesamol (2.5-5 μM) exhibited more potent activity of inhibiting platelet aggregation stimulated by collagen than other agonists. Sesamol inhibited collagen-stimulated platelet activation accompanied by [Ca(2+)](i) mobilization, thromboxane A(2) (TxA(2)) formation, and phospholipase C (PLC)γ2, protein kinase C (PKC) and mitogen-activated protein kinase (MAPK) phosphorylation in washed platelets. Sesamol markedly increased cAMP and cGMP levels, endothelial nitric oxide synthase (eNOS) expression and NO release, as well as vasodilator-stimulated phosphoprotein (VASP) phosphorylation. SQ22536, an inhibitor of adenylate cyclase, markedly reversed the sesamol-mediated inhibitory effects on platelet aggregation and p38 MAPK phosphorylation, and sesamol-mediated stimulatory effects on VASP and eNOS phosphorylation, and NO release. Sesamol also reduced hydroxyl radical (OH(●)) formation in platelets. In an in vivo study, sesamol (5 mg/kg) significantly prolonged platelet plug formation in mice. The most important findings of this study demonstrate for the first time that sesamol possesses potent antiplatelet activity, which may involve activation of the cAMP-eNOS/NO-cGMP pathway, resulting in inhibition of the PLCγ2-PKC-p38 MAPK-TxA(2) cascade, and, finally, inhibition of platelet aggregation. Sesamol treatment may represent a novel approach to lowering the risk of or improving function in thromboembolism-related disorders.

Cost-effectiveness of clopidogrel plus aspirin versus aspirin alone for secondary prevention of cardiovascular events: results from the CHARISMA trial

OBJECTIVE

To determine the incremental cost-effectiveness of clopidogrel plus aspirin (C + A) compared with aspirin (A) alone during the Clopidogrel for High Atherothrombotic Risk and Ischemic Stabilization, Management and Avoidance (CHARISMA) trial from a US payer perspective.

BACKGROUND

Although the CHARISMA trial did not find a benefit of adding clopidogrel to aspirin in its overall study cohort, a benefit was suggested in a prespecified subgroup of patients with established cardiovascular (CV) disease. The cost-effectiveness of dual antiplatelet therapy in this population is unknown.

METHODS

Medical resource utilization was assessed prospectively, and costs for hospitalizations, physician services, outpatient care, and medications were assigned using 2007 US dollars. Life expectancy was estimated contingent on fatal and nonfatal CV events using statistical models of long-term survival from the Saskatchewan Health database.

RESULTS

C + A was associated with a 12.5% relative reduction in CV death, myocardial infarction, or stroke compared with A alone (6.9% vs. 7.9%, P = 0.048) over a median 28 months of follow-up. Severe or moderate bleeding events were higher in patients receiving C + A versus A alone (3.6% vs. 2.5%, P < 0.001). Mean cost/patient was $2607 higher for C + A, while projected life expectancy increased by an average of 0.072 years due to fewer in-trial events. The resulting incremental cost-effectiveness ratio (ICER) for C + A was $36,343/year of life gained. Findings were insensitive to discount rate, life expectancy projections, post-event costs, and indirect costs from lost productivity; the ICER was most sensitive to the cost of clopidogrel. Bootstrap analysis demonstrated that the ICER for C + A remained <$50,000/life-year gained in 70.6% of bootstrap replicates and <$100,000/life-year gained in 87.4%.

CONCLUSIONS

Among patients with established CV disease, adding clopidogrel to aspirin appears to increase life expectancy modestly at a cost generally considered acceptable within the US health-care system.

Resource use and costs of treatment with anticoagulation and antiplatelet agents: results of the WATCH trial economic evaluation

BACKGROUND

The Warfarin and Antiplatelet Therapy in Chronic Heart Failure (WATCH) trial revealed no significant differences among 1587 symptomatic heart failure patients randomized to warfarin, clopidogrel, or aspirin in time to all-cause death, nonfatal myocardial infarction, or nonfatal stroke. We compared within-trial medical resource use and costs between treatments.

METHODS AND RESULTS

We assigned country-specific costs to medical resources incurred during follow-up. Annualized rates of hospitalizations, inpatient and outpatient procedures, and emergency department visits did not differ significantly between groups. Annualized total costs averaged $5901 (95% confidence interval [CI], $4776-$7520) for the aspirin group, $5646 (95% CI, $4903-$6584) for the clopidogrel group, and $5830 (95% CI, $4838-$7400) for the warfarin group.

CONCLUSIONS

Consistent with clinical findings, our analyses did not identify significant cost differences between treatments.

Involvement of Ca2+ in the inhibition by crocetin of platelet activity and thrombosis formation

Crocetin, a unique carotenoid with potent antioxidative and anti-inflammatory activities, is a major ingredient of saffron used as an important spice and food colorant in various parts of the world. In the present study, the effects of crocetin on platelet activity and thrombosis formation were systematically investigated. Crocetin showed a dose-dependent inhibition of platelet aggregation induced by ADP, collagen, but not by arachidonic acid (AA). Crocetin significantly attenuated dense granule release, while neither platelets adhesion to collagen nor cyclic AMP level was altered by crocetin. Pretreatment with crocetin was confirmed to partially inhibit Ca (2+) mobilization via reducing both intracellular Ca (2+) release and extracellular Ca (2+) influx. Besides that, crocetin prolonged the occlusive time in electrical stimulation-induced carotid arterial thrombosis. These findings suggest that the favorable impacts of crocetin on platelet activity and thrombosis formation may be related to the inhibition of Ca (2+) elevation in stimulated platelets.

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.

Inhibitory mechanisms of resveratrol in platelet activation: pivotal roles of p38 MAPK and NO/cyclic GMP

Resveratrol has been reported to have antiplatelet activity; however, the detailed mechanisms have not yet been resolved. This study aimed to systematically examine the detailed mechanisms of resveratrol in the prevention of platelet activation in vitro and in vivo. Resveratrol (0.05-0.25 micromol/l) showed stronger inhibition of platelet aggregation stimulated by collagen (1 microg/ml) than other agonists. Resveratrol (0.15 and 0.25 micromol/l) inhibited collagen-induced platelet activation accompanied by [Ca(+2)]i mobilization, thromboxane A(2) (TxA(2)) formation, phosphoinositide breakdown, and protein kinase C (PKC) activation. Resveratrol markedly increased levels of NO/cyclic guanosine monophosphate (GMP), and cyclic GMP-induced vasodilator-stimulated phosphoprotein phosphorylation. Resveratrol markedly inhibited p38 mitogen-activated protein kinase (MAPK) but not Jun N-terminal kinase or extracellular signal-regulated kinase-2 phosphorylation in washed platelets. Resveratrol-reduced hydroxyl radical (OH(-)) formation in the electron spin resonance study. In an in vivo study, resveratrol (5 mg/kg) significantly prolonged platelet plug formation of mice. In conclusion, the main findings of this study suggest that the inhibitory effects of resveratrol possibly involve (i) inhibition of the p38 MAPK-cytosolic phospholipase A(2)-arachidonic acid-TxA(2)-[Ca(+2)]i cascade and (ii) activation of NO/cyclic GMP, resulting in inhibition of phospholipase C and/or PKC activation. Resveratrol is likely to exert significant protective effects in thromboembolic-related disorders by inhibiting platelet aggregation.

Cost-effectiveness of antiplatelet therapy for secondary stroke prevention

Antiplatelet therapy is recommended over anticoagulants for the secondary prevention of vascular death in patients with noncardioembolic ischemic stroke or transient ischemic attack based upon the 2006 American Heart Association/American Stroke Association guidelines for the prevention of stroke and the National Stroke Association guidelines for the management of transient ischemic attack. Aspirin is commonly used as a cornerstone antiplatelet agent considering its mild but definite prevention benefit and low costs. Other antiplatelet strategies that are currently recommended include extended-release dipyridamole plus low-dose aspirin (Aggrenox((R)), Asasantin((R))) and clopidogrel. In this brief review, we evaluate the cost-effectiveness of antiplatelet agents for secondary stroke prevention to better understand the socioeconomical value of the recommended agents.

Peripheral arterial disease: diagnosis, treatment, and systemic implications

Peripheral arterial disease is common in adults and is found in many patients with lower extremity ulcers. It is important to diagnose peripheral arterial disease not only because of its impact on the involved lower extremity but also because it often occurs with atherosclerotic disease in other vascular beds. Although patient symptoms may be helpful in the diagnosis, most afflicted patients either are asymptomatic or have atypical symptoms. Physical examination, an ankle-brachial index, referral to a noninvasive vascular laboratory, contrast angiography, and magnetic resonance angiography can be helpful diagnostically. Beneficial therapies include smoking cessation, exercise therapy, cholesterol reduction, antiplatelet therapy, and treatment of hypertension and diabetes. For patients with symptomatic claudication, cilostazol can be considered. Patients with nonhealing ulcers, rest pain, or severe claudication should be referred for interventions.

Impact du choix d'un antiagrégant plaquettaire dans l'artériopathie oblitérante des membres inférieurs sur les pertes de chances et sur les coûts médicaux

OBJECTIVES

To evaluate in peripheral arterial disease two strategies of antiplatelet therapy (clopidogrel and aspirin) in terms of number of ischemic stroke and hemorrhagic events, to estimate the losses of chances after no-choice of the most favorable strategy and the impact of these losses of chances in terms of days of hospitalizations, to estimate the cost-effectiveness ratio of the most effective and best tolerated strategy.

METHOD

The number of patients to be treated to avoid one critical event (ischemic and hemorrhagic events) was calculated from the results of the annual rates established by the CAPRIE trial conducted in a population of French patients with peripheral arterial disease. This number of patients to treat was then extrapolated to the entire French population of peripheral arterial disease patients. The absolute numbers of critical events avoided with clopidogrel in France defined the losses of chances in the case of no-choice of this drug. Estimates in terms of days of hospitalization and cost-effectiveness ratio (in euro per life year gained) were based on data from the French Medical Information System.

RESULTS

The number of patients to treat to avoid one ischemic event was 87 and the number of patients to treat to avoid one major hemorrhagic event was 149. In the peripheral arterial disease population, the numbers of ischemic and hemorrhagic events generated by non-treatment with clopidogrel was estimated at 3761 and 2191, respectively i.e. a total of 5952 events per year. These events included: 2025 myocardial infarctions, 1157 ischemic strokes, 579 deaths of vascular origin and 2191 digestive hemorrhages, requiring 60,394 hospitalization days. The cost-effectiveness ratio of clopidogrel was 10,393 euro per life year gained, and was much lower than commonly accepted cost-effective thresholds in Europe, which are around 30,000 euro per life year gained.

CONCLUSION

The choice of clopidogrel in patients with peripheral arterial disease improves the prevention of subsequent events (ischemic and hemorrhagic events) with a cost-effectiveness ratio 2 to 3 times lower than the European thresholds accepted by the World Health Organization and avoids 1 day of hospitalization for 5.4 treated patients.

Clopidogrel

Clopidogrel (Plavix), Iscover) selectively and irreversibly inhibits adenosine diphosphate (ADP)-induced platelet aggregation. Long-term administration of clopidogrel was associated with a modest but statistically significant advantage over aspirin in reducing adverse cardiovascular outcomes in patients with established cardiovascular disease in the CAPRIE trial. In other large well designed multicentre trials, such as CURE, COMMIT and CLARITY-TIMI 28, the addition of clopidogrel to aspirin therapy improved outcomes in patients with acute coronary syndromes. However, some issues regarding the use of clopidogrel remain unresolved, such as the optimal loading dose in patients undergoing percutaneous coronary interventions (PCI) and the optimal treatment duration following drug-eluting intracoronary stent placement. Results of several large randomised trials, therefore, have established clopidogrel as an effective and well tolerated antiplatelet agent for the secondary prevention of ischaemic events in patients with various cardiovascular conditions, including those with ischaemic stroke or acute coronary syndromes. In addition, treatment guidelines from the US and Europe acknowledge the importance of clopidogrel in contemporary cardiovascular medicine.

A cost-effectiveness analysis of n-3 PUFA (Omacor) treatment in post-MI patients

This study evaluates the cost-effectiveness of Omacor treatment as a standard prevention measure post-MI in the UK. A cost-effectiveness model was developed based on the GISSI-P trial, combining a survival and a Markov model, over a lifetime period. The base case results for Omacor, at 4 years and over a lifetime, respectively, were: cost [corrected] per QALY gained: pound15,189 and 3,723; [corrected] cost per life years gained (LYG): pound12,011 and pound2,812 [corrected] The cost per death avoided at 4 years was pound31,786. Deterministic and probabilistic sensitivity analyses did not change the base case results substantially. The use of Omacor as a standard post-MI prevention treatment seems warranted in the UK, both on the basis of its efficacy, which is in addition to other prophylactic treatments as evidenced by the results of the GISSI-P trial, and on cost-effectiveness grounds - both at 4 years and over a lifetime's time-horizon, using the current cost-effectiveness thresholds.

Intermittent claudication: an overview

Intermittent claudication (IC) is defined by leg muscle pain, cramping and fatigue brought on by ambulation/exercise; relieved on rest; and caused by inadequate blood supply and is the primary symptom of peripheral arterial disease (PAD). PAD has a detrimental effect on the quality of life. PAD is a debilitating atherosclerotic disease of the lower limbs and is associated with an increased risk of cardiovascular morbidity and mortality. IC is an extremely important marker of atheroma. Up to 60% patients with IC have significant underlying coronary and/or carotid disease and 40% of all patients suffering from IC die or suffer a stroke within 5 years of presentation. The therapeutic intervention of IC essentially aims at providing symptomatic relief and reducing the systemic cardiovascular complications. Although exercise therapy is one of the most efficacious conservative treatments for claudication, the pharmacotherapeutic goals can be best achieved through an increase in the walking capacity to improve quality of life and a decrease in rates of amputation. In the development of treatment for IC, an aggressive non-pharmacological intervention and pharmacological treatment of the risk factors associated with IC are considered. In the next 2 years, the results of major trials of drugs that stabilize and regress atherosclerosis such as statins and angiotensin converting enzyme inhibitors, and anti-platelet agents, recombinant growth factors and immune modulators will be available for IC. Levocarnitine (l-carnitine) and a derivative, propionyl levocarnitine, are emerging agents that increase the pain-free walking and improve the quality of life in IC patients by working at the metabolism and exercise performance of ischemic muscles. This article provides a comprehensive review of the pathophysiology involved, diagnosis of IC and existing and emerging pharmacotherapies with rationale for their use in its treatment.

Effect on platelet function of cilostazol, clopidogrel, and aspirin, each alone or in combination

Management of peripheral arterial disease (PAD) requires standard atherosclerotic risk management interventions. However, PAD is often complicated by walking pain (intermittent claudication [IC]), which requires symptom-specific therapies as well. Thus, all PAD patients are encouraged to take antiplatelet agents to reduce the associated risks of major cardiovascular events, and those with IC may also require treatment with cilostazol, an agent proven to increase exercise capacity and enhance quality of life in these patients. Although it was initially thought that cilostazol's antiplatelet properties might render it unsafe to use in combination with other platelet inhibitors because of possible additive effects, a recent study has dispelled such concerns. There is evidence that in a crossover trial of 21 patients with PAD and IC, aspirin alone, or clopidogrel alone, significantly increased bleeding times, but cilostazol alone did not. The combination of aspirin and clopidogrel had a greater effect on increasing bleeding time than either monotherapy, and no further bleeding time prolongation was observed, when cilostazol was added to any aspirin/clopidogrel regimen. These findings suggest that PAD patients with IC may be safely managed with both cilostazol and standard antiplatelet therapy, without increasing the risk of adverse bleeding effects.