Cost effectiveness of thrombolytic therapy with tissue plasminogen activator as compared with streptokinase for acute myocardial infarction

Molecular mechanisms of plasminogen activation: bacterial cofactors provide clues

Plasminogen activation is a key event in the fibrinolytic system that results in the dissolution of blood clots, and also promotes cell migration and tissue remodelling. The recent structure determinations of microplasmin in complex with the bacterial plasminogen activators staphylokinase and streptokinase have provided novel insights into the molecular mechanisms of plasminogen activation and cofactor function. These bacterial proteins are cofactor molecules that contribute to exosite formation and enhance the substrate presentation to the enzyme. At the same time, they modulate the specificity of plasmin towards substrates and inhibitors, making a 'specificity switch' possible.

Debate: Should the elderly receive thrombolytic therapy, or primary angioplasty, for acute myocardial infarction? The case for primary angioplasty

As the population ages the number of elderly patients presenting with acute myocardial infarction (AMI) will continue to increase. There has been no head-to-head trial of thrombolytic therapy versus primary percutaneous coronary intervention (PCI) in this patient cohort, but there is evidence that favors primary PCI. Most elderly patients are candidates for primary PCI, but many have contraindications to thrombolytic therapy. Hemorrhagic complications are more common in the elderly, and many of these patients present with conditions in which thrombolytic agents have decreased efficacy, such as heart failure or prior bypass surgery. PCI can also obviate the need for further risk stratification in most patients.

Economics and Quality of Life After Acute Myocardial Infarction: Insights from GUSTO-I

Reperfusion therapy for acute myocardial infarction is one of the most thoroughly studied treatments in all of medicine. The GISSI-1 and ISIS-2 megatrials definitively established the superiority of intravenous streptokinase over conservative care for this condition. Tissue plasminogen activator (t-PA) was introduced with the expectation that it would be substantially more effective than streptokinase. It was also priced at approximately $2000, more than streptokinase, a cost differential that set the stage for a heated and often contentious debate about the added value of t-PA. Two European trials, GISSI-2 and ISIS-3, subsequently found that t-PA and streptokinase provided equivalent health outcomes. It was in this setting that the GUSTO trial was conceived. The major result of GUSTO was the finding that accelerated t-PA saved 11 additional lives per 1000 patients treated. In order to address the question of whether the extra benefits of t-PA were worth its significant extra costs, we performed a detailed cost-effectiveness analysis using the empirical data from the GUSTO-I trial. The net incremental cost for each patient shifted from streptokinase to t-PA in GUSTO-I was;dollar;2845. The majority of this difference was attributable to the difference in the cost of the thrombolytic agents. Survival modeling showed that accelerated t-PA added 0.14 undiscounted years per patient or, alternatively, that each of the 11 extra survivors per 1000 patients shifted from streptokinase to t-PA lived an average of 14 additional years. The incremental cost-effectiveness ratio for routine substitution of t-PA for streptokinase was;dollar;32,678 per added life year. Compared with standard benchmarks, our analysis shows that routine substitution of t-PA for streptokinase is "economically attractive." Subgroups analysis further showed that cost-effectiveness ratios were most favorable in older patients and in anterior myocardial infarctions. Perhaps one of the most important results of the GUSTO-I trial is that it demonstrates that an expensive new biotechnology therapy can have a favorable economic profile if it produces sufficient additional health benefits.

Outcomes at 1 year and economic implications of platelet glycoprotein IIb/IIIa blockade in patients undergoing coronary stenting: results from a multicentre randomised trial. EPISTENT Investigators. Evaluation of Platelet IIb/IIIa Inhibitor for Stenting

BACKGROUND

We assessed in a randomised trial the long-term outcomes for potent adjunctive antiplatelet therapy given at the time of coronary stenting.

METHODS

In 63 hospitals in the USA and Canada, 2399 patients were randomly assigned stenting with abciximab, stenting with placebo, or balloon angioplasty with abciximab. Standard adjunctive therapy with aspirin, ticlopidine, and heparin was used. The major outcomes of death and myocardial infarction were assessed at 1-year follow-up by intention to treat. We also investigated the 1-year cost-effectiveness of combined stenting and abciximab therapy.

FINDINGS

At 1-year follow-up, eight (1.0%) of 794 patients in the stent plus abciximab group had died, compared with 19 (2.4%) of 809 in the stent plus placebo group (hazard ratio 0.43 [95% CI 0.19-0.97], p=0.037). The combined endpoint of death or large myocardial infarction occurred in 42 (5.3%) and 89 (11.0%), respectively (0.46 [0.32-0.67], p<0.001). By multivariate modelling, the factors independently associated with improved survival were assignment to stenting with abciximab (p=0.027) and greater preprocedural stenosis (p=0.002); those associated with worse survival were age greater than 70 years (p<0.001), previous heart failure (p=0.001), diabetes treated with insulin (p=0.02), and postprocedural occlusion (p<0.001). Relative to stenting plus placebo and balloon angioplasty plus abciximab, the incremental 1-year costs of stenting plus abciximab were US$581 and $932. The corresponding cost-effectiveness ratios were US$5291 and $6213 per added life-year.

INTERPRETATION

Coronary stenting with abciximab, compared with stenting alone or balloon angioplasty with abciximab, is associated with improved survival and is an economically attractive therapy by conventional standards.

Cost estimates for treatment of cardiac ischemia (from the Asymptomatic Cardiac Ischemia Pilot [ACIP] study)

Costs for management of myocardial ischemia are enormous, yet comparison cost and outcome data for various ischemia treatment strategies from randomized trials are lacking and will require cost and resource utilization data from a large prospective trial. The Asymptomatic Cardiac Ischemia Pilot provided feasibility data for planning such a trial and an opportunity to estimate the long-term costs of different treatment strategies. Economic implications for ischemia management were compared in 558 patients with stable coronary artery disease and myocardial ischemia during both stress testing and daily life. Participants were randomized to 3 different initial treatment strategies and followed for 2 years. Based on cost trends over follow-up, costs for subsequent care were estimated. As expected, due to initial procedural costs, at 3 months, estimated costs for revascularization were approximately 10 times greater than costs for a medical care strategy. Extrapolated costs for anticipated resource consumption for care beyond 2 years, however, were approximately 2 times greater for an initial medical care strategy than for initial revascularization. This was due to increased need for drugs and hospitalizations for both late revascularizations and other ischemia-related events. Estimated costs for anticipated care in the medical strategies reached the anticipated cost of the revascularization strategy within 10 years. Because this cost-equal time period is well within the median life expectancy for such a patient population, these findings could have important public health implications and require testing in a full-scale prognosis trial. We anticipate that over the patients' life expectancy, early revascularization is likely to become either cost-neutral or cost-effective.

Cost analysis of diagnostic testing for coronary artery disease in women with stable chest pain. Economics of Noninvasive Diagnosis (END) Study Group

BACKGROUND

Seven clinical sites compiled data from 4638 women who were referred directly to coronary angiography (catheterization-first strategy; n = 3375) or who underwent stress myocardial perfusion imaging (MPI) first (n = 1263) followed by coronary angiography if at least one reversible myocardial perfusion abnormality was detected. The study examines the cost minimization potential of these available invasive and noninvasive diagnostic strategies in women with chest pain.

METHODS AND RESULTS

Women in both groups were subclassified by the core laboratory as being at low (<0.15), intermediate (0.15 to 0.60), or high (>0.60) pretest likelihood for coronary artery disease (CAD). Among the catheterization-first patients, at least one coronary stenosis >70% was present in 13% of low likelihood patients, 29% of intermediate likelihood patients, and 52% of patients with high CAD likelihood. Perfusion abnormality rates in the MPI-first group were 23% in low likelihood patients, 27% in intermediate likelihood patients, and 34% in high CAD likelihood patients. Of the MPI-first subset, 50%, 55%, and 76%, respectively, underwent catheterization in at least one coronary stenosis >70%. Cardiac death rates ranged from 0.5% to 2.2% in patients with CAD and did not differ from the 2 testing strategies (P = not significant). The composite cost per patient of diagnostic testing plus follow-up medical care over a period of 2.5 +/- 1.5 years (calculated for both strategies from inflation-corrected Medicare charges, adjusted for institutional cost-charge ratios) ranged from $2490 for patients with low likelihood to $3687 for patients with high likelihood with the catheterization-first strategy and from $1587 to $2585 for patients undergoing MPI first (P < .01 between risk subsets and strategies).

CONCLUSIONS

In women referred for diagnostic evaluation of stable chest pain, MPI followed by selective coronary angiography in patients with at least 1 perfusion abnormality minimizes the near-term composite cost per patient compared with a direct catheterization-first strategy, regardless of pretest CAD likelihood.

The cost-effectiveness of losartan versus captopril in patients with symptomatic heart failure

The Losartan Heart Failure ELITE Study recently found that in patients with symptomatic heart failure and a left ventricular ejection fraction of </=0.40, losartan compared to captopril improved survival with better tolerability. The objective of this study was to perform an economic evaluation of losartan versus captopril based on the results of the Losartan Heart Failure ELITE Study. The Losartan Heart Failure ELITE Study was a multinational, double-blind, randomized 48-week study comparing the safety and efficacy of losartan to captopril in angiotensin-converting enzyme-inhibitor-naive patients >/=65 years with symptomatic heart failure. Data on health care resource utilization were collected as part of the trial. We conducted a cost-effectiveness analysis to estimate the lifetime benefits of treatment and the associated costs. We observed no differences between treatments in the number of hospitalizations, hospital days, and emergency room visits per patient over the trial period. We estimated the total cost of losartan to be USD 54 (95% CI: USD -1,717, USD 1,755) less per patient than captopril over this time frame. We also estimated that over the projected remaining lifetime of the study population, losartan compared to captopril would increase survival by 0.20 years (undiscounted) at an average cost of USD 769 (discounted) more per patient. This cost increase translated into a cost-effectiveness ratio of USD 4,047 per year of life gained for losartan relative to captopril. In patients with symptomatic heart failure, losartan compared to captopril increased survival with better tolerability at a cost well within the range accepted as cost-effective.

Medical decision making in the choice of a thrombolytic agent for acute myocardial infarction. Quebec Acute Coronary Care Working Group

Little is known about how physicians make decisions when the evidence is incomplete or controversial. While thrombolysis improves survival following acute myocardial infarction (AMI), conflicting evidence exists as to any specific agent's superiority, particularly if cost-effectiveness is considered. Using a Bayesian hierarchical model, the authors examined the patient, physician, and hospital characteristics that are related to the decision-making process concerning the choice of thrombolytic agent in a prospective registry of 1,165 AMI patients receiving thrombolysis. Tissue plasminogen activator (t-PA) was administered to 432 patients (31.8%) and streptokinase (SK) to the remainder. The presence of an anterior infarction, a previous myocardial infarction, low blood pressure, a cardiologist decision maker, younger age, and receiving treatment within six hours after the start of symptoms were independent predictors of receiving t-PA. The levels of importance that physicians accorded to these patient characteristics differed according to their practicing institutions. Generally, they followed evidence-based medicine and reasonably targeted high-risk patients to receive the more expensive t-PA. However, they also preferentially treated younger patients, where only a small absolute advantage appears to exist.

Current state of thrombolytic therapy

More than 200,000 people have been enrolled into clinical trials examining different reperfusion strategies for patients with acute myocardial infarction. Each year approximately 1 million people in the United States experience acute myocardial infarction. Thrombolytic agents, including streptokinase and tissue-type plasminogen activator, activate plasminogen. These agents are often divided into "fibrin-specific" and "non-fibrin-specific" drugs. New thrombolytic agents designed to address several of the shortcomings of existing thrombolytics are in various stages of clinical development.

A catalytic switch and the conversion of streptokinase to a fibrin-targeted plasminogen activator

Plasminogen (Pg) activators such as streptokinase (SK) save lives by generating plasmin to dissolve blood clots. Some believe that the unique ability of SK to activate Pg in the absence of fibrin limits its therapeutic utility. We have found that SK contains an unusual NH(2)-terminal "catalytic switch" that allows Pg activation through both fibrin-independent and fibrin-dependent mechanisms. Unlike SK, a mutant (rSKDelta59) fusion protein lacking the 59 NH(2)-terminal residues was no longer capable of fibrin-independent Pg activation (k(cat)/K(m) decreased by >600-fold). This activity was restored by coincubation with equimolar amounts of the NH(2)-terminal peptide rSK1-59. Deletion of the NH(2) terminus made rSKDelta59 a Pg activator that requires fibrin, but not fibrinogen, for efficient catalytic function. The fibrin-dependence of the rSKDelta59 activator complex apparently resulted from selective catalytic processing of fibrin-bound Pg substrates in preference to other Pg forms. Consistent with these observations, the presence (rSK) or absence (rSKDelta59) of the SK NH(2)-terminal peptide markedly altered fibrinolysis of human clots suspended in plasma. Like native SK, rSK produced incomplete clot lysis and complete destruction of plasma fibrinogen; in contrast, rSKDelta59 produced total clot lysis and minimal fibrinogen degradation. These studies indicate that structural elements in the NH(2) terminus are responsible for SK's unique mechanism of fibrin-independent Pg activation. Because deletion of the NH(2) terminus alters SK's mechanism of action and targets Pg activation to fibrin, there is the potential to improve SK's therapeutic efficacy.

Cost-effectiveness of reperfusion strategies

Reperfusion of acute myocardial infarction has become the standard of management during the first few hours. Cost per year of life saved is one measure of the effectiveness of reperfusion strategies. Estimates of the cost per year of life saved have been approximately $17,000 for streptokinase and percutaneous transluminal coronary angioplasty and approximately $33,000 for tissue plasminogen activator. Assuming that percutaneous transluminal coronary angioplasty is more effective than thrombolysis, we calculated the cost-effectiveness of this strategy in different hospital settings. The estimated costs in hospitals with existing cardiac catheterization laboratories were $11,000 per year of life saved for primary angioplasty and $14,000 for thrombolysis compared with no intervention. In hospitals without catheterization facilities, it would be cost-ineffective to build such laboratories only to treat acute infarction with angioplasty. Preliminary results suggest that stenting may also be cost-effective in association with angioplasty.

Cost-effectiveness of stress-echocardiography

Because of constraints on the costs of providing medical care, cardiologists in the future will find themselves challenged to provide care for their patients in the most cost-effective manner possible. Although stress-echocardiography has been shown to compare favorably with other tests in diagnostic accuracy, data on cost-effectiveness are scarce. In this article, general concepts of cost-effectiveness as they relate to stress-echocardiography are reviewed and the available literature is summarized. Although definitive data are lacking, there is evidence to suggest that stress-echocardiography may prove to be cost-effective in several clinical situations.

Economic evaluation of pharmacy services--fact or fiction?

Previous attempts to conduct economic evaluation of pharmacy services are almost exclusively from the US and the UK. Studies from the US concentrate largely on the drug cost savings realised by pharmacists. Few detail the costs of service provision and even fewer give an estimate of service benefits other than decreased drug expenditure. UK evaluation to date focuses on quantifying pharmacists' interventions, but there is no clear indication of the quality or the impact of these. This article proposes a model for economic evaluation and discusses the factors which make evaluation results useful to decision makers. The costs and outcomes, that need to be considered for economic evaluation, are discussed and the example of a pharmacist led anticoagulation clinic is used. The nature of modern health care systems demands that services are effective and, increasingly, cost-effective. If pharmacy as a profession is to develop, decision makers must decide that pharmaceutical care delivered by pharmacists is a cost-effective use of health care resources. Politics, education and cost pressures will mean that decision makers are likely to put more weight on the results of economic evaluation in future. If pharmacists do not start to provide good quality data about the costs and outcomes of pharmacy services then other evaluators will.

Cost-effectiveness of treatment of early stage endometrial cancer

OBJECTIVE

The purpose of this study was to determine the average life-years gained and cost per life-year gained in treatment of early endometrial cancer.

METHODS

We performed a decision analysis using statistical models for survival after treatment for Stage I endometrial cancer. Estimates for survival probabilities without treatment, with surgery alone, and with surgery and radiation were derived from the literature. Charges and costs of treatment were estimated based on data from our institution. We calculated the average number of life-years gained and the cost per life-year gained of various treatment options based on these estimates. Sensitivity analyses were performed to determine the effect of uncertainty about parameter estimates on the results derived from our model.

RESULTS

Based on the assumptions of our model, most of the life-years gained in treatment of early endometrial cancer are attributable to hysterectomy, with a very low associated cost. For the "average" woman with endometrial cancer, about 10 life-years are gained from hysterectomy at a cost of $1000 per life-year gained, whereas adjuvant radiation yields on average 1 year of life gained at $4000 per life-year gained. Both life-years gained and cost are dramatically affected by age at diagnosis and to a lesser extent by histologic grade and comorbid medical conditions.

CONCLUSIONS

This analysis suggests that the use of hysterectomy and adjuvant radiation in treatment of early endometrial cancer is a worthwhile use of health care resources. More sophisticated models may help determine the cost-effectiveness of various treatment strategies in specific subgroups of patients.

Monte Carlo estimation of extrapolation of quality-adjusted survival for follow-up studies

The expected quality-adjusted survival (QAS) for an index population with a specific disease can be estimated by summing the product of the survival function and the mean quality of life function of the population. In many follow-up studies with heavy censoring, the expected QAS may not be well estimated due to the lack of data beyond the close of follow-up. In this paper, we first created a reference population from the life tables of the general population according to the Monte Carlo method. Secondly, we fitted a simple linear regression line to the logit of the ratio of quality-adjusted survival functions for the index and reference populations up to the end of follow-up. Finally, combining information on the reference population with the fitted line, we predicted the expected quality-adjusted survival curve beyond the follow-up period for the index population. Simulation studies have shown that the simple Monte Carlo estimation procedure is a potential approach for estimating expected QAS and the survival function beyond the follow-up with a certain degree of accuracy.

Platelet reactivity and streptokinase resistance following antecedent streptokinase therapy for myocardial infarction

AIMS

To assess the efficacy of second-time administration of streptokinase (SK). First-time thrombolysis with SK in myocardial infarction (MI) is established but the efficacy of subsequent SK is unknown.

METHODS AND RESULTS

Platelet reactivity to shear stress, spontaneous and SK-induced thrombolysis were measured in vitro in 28 patients who had received SK for MI and compared to 15 controls. SK antibody (Ab) titres were inversely related to time from MI. Platelet reactivity was greatly enhanced in patients (p < 0.0001). Spontaneous thrombolysis in patients was poor and in 17 failed to occur. In contrast, thrombolysis occurred in all but 1 control. In patients platelet reactivity was strongly related to thrombolytic activity (r = -0.516; p = 0.0029). SK in vitro was at least 4 times more effective in controls than in patients.

CONCLUSION

The chances of achieving patency with second administration of SK are poor. Ab titre is not a reliable predictor of resistance.

The treatment and prevention of coronary heart disease in Canada: do older patients receive efficacious therapies? The Clinical Quality Improvement Network (CQIN) Investigators

OBJECTIVES

To review the evidence for clinical efficacy and cost-effectiveness of proven medications in the treatment and prevention of myocardial infarction (MI) in older patients; to summarize Canadian data on treatment patterns and clinical outcomes for younger and older patients with coronary heart disease; to explore the reasons for gaps between best care, based on the evidence of efficacy from trials, and usual care, based on the population effectiveness audits; and to explore potential approaches to closing the care gaps.

DESIGN

Review of the recent clinical trial literature on the management of MI, highlighting results in older patients. Review of medication utilization and outcomes data from a series of large, consecutively enrolled patient cohorts with acute MI (N = 7070) in a variety of cardiac care settings (10 centers in five Canadian provinces, including university-based teaching hospitals, community hospitals, cardiologist and family physician out-patient clinics) from 1987 to 1996.

RESULTS

There is no qualitative interaction of cardiac therapies: thrombolytics, beta-blockers, acetylsalicylic acid (ASA), and statins are efficacious in all clinically relevant patient subgroups, including older people. However, there are consistent gaps between usual care and best care, particularly among older patients (in whom there is also a concomitantly higher mortality risk). Repeated multivariate analyses confirm older age to be an independent contributor to increased risk. Use of efficacious medications is, in contrast, consistently associated with increased survival. Analysis of temporal trends suggests beneficial changes in practice patterns and outcomes are possible to achieve. However, "best care" has not been rapidly or completely achieved. Review of strategies to close these care gaps suggests that audit and feedback, critical pathways, and multifactorial interventions involving patients and other members of the healthcare team as well as physicians may be the most efficacious strategies for change.

CONCLUSIONS

Despite equal or enhanced efficacy, there is consistently less prescription of proven drugs among older cardiac patients. These care patterns may contribute to their enhanced risk. The causes underlying these practice patterns are complex, and their population impact may be undervalued by clinicians and managers. Improvement of these patterns is difficult, but ultimately it would be beneficial for this presently disadvantaged, readily identified, high risk patient population.

How to use the results of an economic evaluation

BACKGROUND

Given the high costs of delivering care to critically ill patients, practitioners and policymakers are beginning to scrutinize the costs and outcomes associated with intensive care. Health economics is a discipline concerned with determining the best way of using resources to maximize the health of the community. This involves addressing questions such as which procedure, test, therapy, or program should be provided, and to whom, given available resources.

PURPOSE

The purpose of this article is to review general economic principles that will help intensivists to better interpret published economic evaluations.

DATA SOURCES

Selected articles from the health economics and critical care literature.

RESULTS

In this article, we use an economic evaluation that examines sedation strategies in critically ill patients. We discuss how learning to critically appraise an economic evaluation is only part of the task for end users. Determining whether and how to apply the results of economic evaluations to local settings presents bigger challenges and remains largely a matter of judgment.

CONCLUSIONS

Economic evaluations use analytic techniques to systematically consider all possible costs and consequences of clinical actions. Although they should never form the sole basis for clinical decisions for individual patients, economic evaluations offer potentially useful information at different levels of decision-making.

Sample size and power issues in estimating incremental cost-effectiveness ratios from clinical trials data

It is becoming increasingly more common for a randomized controlled trial of a new therapy to include a prospective economic evaluation. The advantage of such trial-based cost-effectiveness is that conventional principles of statistical inference can be used to quantify uncertainty in the estimate of the incremental cost-effectiveness ratio (ICER). Numerous articles in the recent literature have outlined and compared various approaches for determining confidence intervals for the ICER. In this paper we address the issue of power and sample size in trial-based cost-effectiveness analysis. Our approach is to determine the required sample size to ensure that the resulting confidence interval is narrow enough to distinguish between two regions in the cost-effectiveness plane: one in which the new therapy is considered to be cost-effective and one in which it is not. As a result, for a given sample size, the cost-effectiveness plane is divided into two regions, separated by an ellipse centred at the origin, such that the sample size is adequate only if the truth lies on or outside the ellipse.

Cost-effectiveness analysis of alternative factor VIII products in treatment of haemophilia A

Manufactured factor VIII (FVIII) concentrates of varying purity are available for managing patients with haemophilia A. This study is a cost-effectiveness analysis of ultra-high purity and recombinant (UHP/R) FVIII products relative to intermediate and very-high purity (IP/VHP) preparations. Because the societal (including research and development) costs of FVIII products are unknown and product prices vary with market conditions, we conducted the analysis with treatment cost as a variable quantity. We estimated the largest price premium that could be paid for a UHP/R concentrate relative to an IP/VHP concentrate such that the UHP/R product is the more cost-effective preparation. In the analysis haemophilic patients were assumed to be seropositive for human immunodeficiency virus, seropositive for hepatitis C (HCV), or at risk for seroconversion of hepatitis A (HAV) or hepatitis B (HBV). The results showed that the maximum cost-effective UHP/R price premium is essentially zero if the patient is only at risk of HAV or HBV infection, positive but small for the base-case HCV+ patient, and positive and large for the base-case HIV+ patient having a short life expectancy. Thus UHP/R preparations are not uniformly more cost-effective than IP/VHP products across the spectrum of haemophilic patients' health problems, and the relative cost-effectiveness of the two classes of prepared FVIII products is sensitive to product prices. The methodology employed here can be used in other circumstances where multiple treatments exist for illnesses for which there are significant multiple comorbidities or health risks.

Pharmacoeconomics research credibility: a controversial and recurring theme in health outcomes research

OBJECTIVE

This paper provides a framework for and discussion of the continued development and adoption of good health outcomes practice with application to health outcomes research.

METHODS

We explored the issue of credibility in health outcomes research, including efforts within academia, governments, industry, and other interested parties to elevate the standard of health outcomes research to that currently expected of clinical research. A large percentage of health outcomes research programs are designed, implemented, and funded through efforts of the pharmaceutical industry; this fact casts doubt on the validity of study findings, with the result that these results often may be disregarded entirely.

CONCLUSIONS

The constantly increasing need to demonstrate value for money in the context of health-care interventions is likely to continue as the need for continued high quality medical care persists and health-care budgets decline. Efforts aimed at guiding healthcare expenditures, such as health outcomes research, require further examination and attention.

Cost effectiveness of carvedilol for heart failure

In this study, we examine the cost effectiveness of carvedilol for the treatment of chronic heart failure (CHF). We use a Markov model to project life expectancy and lifetime medical care costs for a hypothetical cohort of patients with CHF who were assumed alternatively to receive carvedilol plus conventional therapy (digoxin, diuretics, and angiotensin-converting enzyme inhibitors) or conventional therapy alone. Patients on carvedilol were assumed to experience a reduced risk of death and hospitalization for CHF, which is consistent with findings from the US Carvedilol Heart Failure Trials Program. The benefits of carvedilol were projected under 2 alternative scenarios. In the first ("limited benefits"), benefits were conservatively assumed to persist for 6 months, the average duration of follow-up in these clinical trials, and then end abruptly. In the other ("extended benefits"), they were arbitrarily assumed to persist for 6 months and then decline gradually over time, vanishing by the end of 3 years. We estimated our model using data from the US Carvedilol Heart Failure Trials Program and other sources. For patients receiving conventional therapy alone, estimated life expectancy was 6.67 years; corresponding figures for those also receiving carvedilol were 6.98 and 7.62 years under the limited and extended benefits scenarios, respectively. Expected lifetime costs of CHF-related care were estimated to be $28,756 for conventional therapy, and $36,420 and $38,867 for carvedilol (limited and extended benefits, respectively). Cost per life-year saved for carvedilol was $29,477 and $12,799 under limited and extended benefits assumptions, respectively. The cost effectiveness of carvedilol for CHF compares favorably to that of other generally accepted medical interventions, even under conservative assumptions regarding the duration of therapeutic benefit.

Performing cost-effectiveness analysis by integrating randomized trial data with a comprehensive decision model: application to treatment of acute ischemic stroke

A recent national panel on cost-effectiveness in health and medicine has recommended that cost-effectiveness analysis (CEA) of randomized controlled trials (RCTs) should reflect the effect of treatments on long-term outcomes. Because the follow-up period of RCTs tends to be relatively short, long-term implications of treatments must be assessed using other sources. We used a comprehensive simulation model of the natural history of stroke to estimate long-term outcomes after a hypothetical RCT of an acute stroke treatment. The RCT generates estimates of short-term quality-adjusted survival and cost and also the pattern of disability at the conclusion of follow-up. The simulation model incorporates the effect of disability on long-term outcomes, thus supporting a comprehensive CEA. Treatments that produce relatively modest improvements in the pattern of outcomes after ischemic stroke are likely to be cost-effective. This conclusion was robust to modifying the assumptions underlying the analysis. More effective treatments in the acute phase immediately following stroke would generate significant public health benefits, even if these treatments have a high price and result in relatively small reductions in disability. Simulation-based modeling can provide the critical link between a treatment's short-term effects and its long-term implications and can thus support comprehensive CEA.

The economic consequences of available diagnostic and prognostic strategies for the evaluation of stable angina patients: an observational assessment of the value of precatheterization ischemia. Economics of Noninvasive Diagnosis (END) Multicenter Study Group

OBJECTIVES

The study aim was to determine observational differences in costs of care by the coronary disease diagnostic test modality.

BACKGROUND

A number of diagnostic strategies are available with few data to compare the cost implications of the initial test choice.

METHODS

We prospectively enrolled 11,372 consecutive stable angina patients who were referred for stress myocardial perfusion tomography or cardiac catheterization. Stress imaging patients were matched by their pretest clinical risk of coronary disease to a series of patients referred to cardiac catheterization. Composite 3-year costs of care were compared for two patients management strategies: 1) direct cardiac catheterization (aggressive) and 2) initial stress myocardial perfusion tomography and selective catheterization of high risk patients (conservative). Analysis of variance techniques were used to compare costs, adjusting for treatment propensity and pretest risk.

RESULTS

Observational comparisons of aggressive as compared with conservative testing strategies reveal that costs of care were higher for direct cardiac catheterization in all clinical risk subsets (range: $2,878 to $4,579), as compared with stress myocardial perfusion imaging plus selective catheterization (range: $2,387 to $3,010, p < 0.0001). Coronary revascularization rates were higher for low, intermediate and high risk direct catheterization patients as compared with the initial stress perfusion imaging cohort (13% to 50%, p < 0.0001); cardiac death or myocardial infarction rates were similar (p > 0.20).

CONCLUSIONS

Observational assessments reveal that stable chest pain patients who undergo a more aggressive diagnostic strategy have higher diagnostic costs and greater rates of intervention and follow-up costs. Cost differences may reflect a diminished necessity for resource consumption for patients with normal test results.

The challenge of health care delivery to the elderly patient with cardiovascular disease. Demographic, epidemiologic, fiscal, and health policy implications

Old age as our society is experiencing it is a new phenomenon. Never before in history have societies of developed countries enjoyed such longevity of life. In the next several decades the United States will face an unparalleled increase in the absolute number of elderly persons in our population. How will health care professionals, policy-makers, and society in general face the mammoth task of providing quality cardiovascular care for the elderly in an environment of limited financial resources? This article discusses the demographic, fiscal, and health policy implications of our aging society with particular emphasis on existing and anticipated impediments to the delivery of cardiovascular care to this rapidly expanding segment of our population.

Economics, health-related quality of life, and cost-effectiveness methods for the TACTICS (Treat Angina With Aggrastat [tirofiban]] and Determine Cost of Therapy with Invasive or Conservative Strategy)-TIMI 18 trial

Concern over escalating health care costs has led to increasing focus on economics and assessment of outcome measures for expensive forms of therapy. This is being investigated in the Treat Angina With Aggrastat [tirofiban] and Determine Cost of Therapy with Invasive or Conservative Strategy (TACTICS)-TIMI 18 trial, a randomized trial comparing outcome of patients with unstable angina or non-Q-wave myocardial infarction treated with tirofiban and then randomized to an invasive versus a conservative strategy. Hospital and professional costs initially and over 6 months, including outpatient costs, will be assessed. Hospital costs will be determined for patients in the United States from the UB92 formulation of the hospital bill, with costs derived from charges using departmental cost to charge ratios. Professional costs will be determined by accounting for professional services and then converted to resource units using the Resource Based Relative Value Scale and then to costs using the Medicare conversion factor. Follow-up resource consumption, including medications, testing and office visits, will be carefully measured with a Patient Economic Form, and converted to costs from the Medicare fee schedule. Health-related quality of life will be assessed with a specific instrument, the Seattle Angina Questionnaire, and a general instrument, the Health Utilities Index at baseline, 1, and 6 months. The Health Utilities Index will also be used to construct a utility. By knowing utility and survival, quality-adjusted life years will be determined. These measures will permit the performance of a cost-effectiveness analysis, with the cost-effectiveness of the invasive strategy defined and the difference in cost between the invasive and conservative strategies divided by the difference in quality-adjusted life years. The economic and health-related quality of life aspects of TACTICS-TIMI 18 are an integral part of the study design and will provide a comprehensive understanding of the impact of invasive versus conservative management strategies on a broad range of outcomes after hospitalization for unstable angina or non-Q-wave myocardial infarction.

Effects of stroke on medical resource use and costs in acute myocardial infarction. GUSTO I Investigators. Global Utilization of Streptokinase and Tissue Plasminogen Activator for Occluded Coronary Arteries Study

BACKGROUND

Stroke occurs concurrently with myocardial infarction (MI) in approximately 30 000 US patients each year. This number is expected to rise with the increasing use of thrombolytic therapy for MI. However, no data exist for the economic effect of stroke in the setting of acute MI (AMI). The purpose of this prospective study was to assess the effect of stroke on medical resource use and costs in AMI patients in the United States.

METHODS AND RESULTS

Medical resource use and cost data were prospectively collected for 2566 randomly selected US GUSTO I patients (from 23 105 patients) and for the 321 US GUSTO I patients who developed non-bypass surgery-related stroke during the baseline hospitalization. Follow-up was for 1 year. All costs are expressed in 1993 US dollars. During the baseline hospitalization, stroke was associated with a reduction in cardiac procedure rates and an increase in length of stay, despite a hospital mortality rate of 37%. Together with stroke-related procedural costs of $2220 per patient, the baseline medical costs increased by 44% ($29 242 versus $20 301, P<0.0001). Follow-up medical costs were substantially higher for stroke survivors ($22 400 versus $5282, P<0.0001), dominated by the cost of institutional care. The main determinant for institutional care was discharge disability status. The cumulative 1-year medical costs for stroke patients were $15 092 higher than for no-stroke patients. Hemorrhagic stroke patients had a much higher hospital mortality rate than non-hemorrhagic stroke patients (53% versus 15%, P<0.001), which was associated with approximately $7200 lower mean baseline hospitalization cost. At discharge, hemorrhagic stroke patients were more likely to be disabled (68% versus 46%, P=0.002).

CONCLUSIONS

In this first large prospective economic study of stroke in AMI patients, we found that strokes were associated with a 60% ($15 092) increase in cumulative 1-year medical costs. Baseline hospitalization costs were 44% higher because of longer mean lengths of stay. Stroke type was a key determinant of baseline cost. Follow-up costs were more than quadrupled for stroke survivors because of the need for institutional care. Disability level was the main determinant of institutional care and thus of follow-up costs.

Local overexpression of thrombomodulin for in vivo prevention of arterial thrombosis in a rabbit model

-Endothelial thrombomodulin plays a critical role in hemostasis by binding thrombin and subsequently converting protein C to its active form, a powerful anticoagulant. Thrombomodulin thus represents a central mechanism by which patency is maintained in normal vessels. However, thrombomodulin expression decreases in perturbed endothelial cells, predisposing to thrombotic occlusion. An adenoviral construct expressing thrombomodulin (Adv/RSV-THM) was created and functionally characterized in vitro and in vivo. The impact of local overexpression of thrombomodulin on in vivo thrombus formation was subsequently examined in a stasis/injury model of arterial thrombosis. The construct prevented arterial thrombosis formation in all animals, while viral and nonviral controls typically developed occluding thrombi. By histological analysis, nonviral controls exhibited intravascular thrombus occluding a mean of 70.52+/-3.72% of available lumen, while viral controls reached 86. 85+/-2.82% thrombotic occlusion; in contrast, Adv/RSV-THM reduced thrombosis to 28.61+/-3.31% of lumen in cross section. No significant intima-to-media ratio was observed in the thrombomodulin group relative to controls. Local infiltration of granulocytes and macrophages significantly decreased in the Adv/RSV-THM group relative to controls, while neutrophilic infiltration increased in viral controls relative to nonviral controls. This construct thus offers a viable technique for promoting a locally thromboresistant small-caliber artery, without the inflammatory damage that has limited many other adenoviral applications.

Cost-effective treatment of the infertile couple

OBJECTIVE

To review the published literature on the cost-effective approach to infertility treatment.

DESIGN

The literature on the economics and cost-effectiveness of infertility treatments was reviewed. Studies related to this topic were identified through MEDLINE.

RESULT(S)

Few cost-effectiveness studies about infertility treatment have been published. In the absence of tubal blockage and severe male factor, use of IUI and hMG-IUI is more cost-effective than IVF. In vitro fertilization is at least as cost-effective as tubal surgery. Although IVF costs are high, they fall well within the range of other accepted medical treatments and are below the general public's willingness to pay for these treatments.

CONCLUSION(S)

Cost-effectiveness analysis is an important means of improving quality of care while controlling costs. Further work regarding cost-effectiveness of treatments among different diagnostic groups is needed.

Prevalence-based economic evaluation

OBJECTIVE

Researchers have often stated that economic evaluations of new drugs have rarely been used to inform healthcare decisions, despite the large volume of published studies. In this paper, a new categorization for economic evaluations of new drugs is proposed: incidence-based and prevalence-based. This categorization is designed to increase the likelihood that decision-makers are given more complete and usable economic information about new treatments.

RESULTS

Incidence-based evaluations (such as cost-effectiveness analysis) focus on the impact of a new treatment on a health condition from onset until cure or death. Prevalence-based evaluations focus on the impact of a new treatment on a health condition during a 1-year period. An incidence-based evaluation may focus either on a representative individual or on a specific disease cohort. A prevalence-based evaluation generally focuses on a specific population. Incidence-based evaluations measure the value of the new treatment compared to alternative treatments for the same health conditions and compared to commonly used treatments for other health conditions. Prevalence-based evaluations measure the impact of introducing the new treatment on annual healthcare budgets and population health.

CONCLUSION

Both types of evaluation provide important information when a new treatment is introduced to a population.

Utilities for major stroke: results from a survey of preferences among persons at increased risk for stroke

BACKGROUND

Patient beliefs, values, and preferences are crucial to decisions involving health care. In a large sample of persons at increased risk for stroke, we examined attitudes toward hypothetical major stroke.

METHODS AND RESULTS

Respondents were obtained from the Academic Medical Center Consortium (n = 621), the Cardiovascular Health Study (n = 321 ), and United Health Care (n = 319). Preferences were primarily assessed by using the time trade off (TTO). Although major stroke is generally considered an undesirable event (mean TTO = 0.30), responses were varied: although 45% of respondents considered major stroke to be a worse outcome than death, 15% were willing to trade off little or no survival to avoid a major stroke.

CONCLUSIONS

Providers should speak directly with patients about beliefs, values, and preferences. Stroke-related interventions, even those with a high price or less than dramatic clinical benefits, are likely to be cost-effective if they prevent an outcome (major stroke) that is so undesirable.

Gains in life expectancy from medical interventions--standardizing data on outcomes

BACKGROUND

The gain in life expectancy is an important measure of the effectiveness of medical interventions, but its interpretation requires that it be placed in context. The interpretation of gains in life expectancy is particularly problematic for preventive interventions, for which the gains are often just weeks or even days when averaged across the entire target population.

METHODS

We tabulated the gains in life expectancy from a variety of medical interventions as reported in 83 published sources and categorized them according to target population and disease. We considered prevention in populations at average risk for particular diseases, prevention in populations at elevated risk, and treatments in populations with established disease.

RESULTS

The gains in life expectancy from preventive interventions in populations at average risk ranged from less than one month to slightly more than one year per person receiving the intervention, but the gains were as high as five years or more if the prevention was targeted at persons at especially high risk. The gains in life expectancy from treatments of established disease ranged from several months (for coronary thrombolysis and revascularization to treat heart disease) to as long as nine years (for chemotherapy to treat advanced testicular cancer).

CONCLUSIONS

A gain in life expectancy from a medical intervention can be categorized as large or small by comparing it with gains from other interventions aimed at the same target population. A gain in life expectancy of a month from a preventive intervention targeted at populations at average risk and a gain of a year from a preventive intervention targeted at populations at elevated risk can both be considered large. The framework we developed for standardizing gains in life expectancy can be used in the interpretation of data on the outcomes of interventions.

Refining the risk-benefit equation for thrombolysis: how to identify the low risk patient before administering thrombolytic therapy

In view of the relative risk of intracranial haemorrhage and major bleeding with thrombolytic therapy, it is important to identify as early as possible the low risk patient who may not have a net clinical benefit from thrombolysis in the setting of acute myocardial infarction. An analysis of 5434 hospital-treated patients with myocardial infarction in the Perth MONICA study showed that age below 60 and absence of previous infarction or diabetes, shock, pulmonary oedema, cardiac arrest and Q-wave or left bundle branch block on the initial ECG identified a large group of patients with a 28 day mortality of only 1%, and one year mortality of only 2%. Identification of baseline risk in this way helps refine the risk-benefit equation for thrombolytic therapy, and may help avoid unnecessary use of thrombolysis in those unlikely to benefit.

Issues in extrapolating from clinical trials to clinical practice and outcomes

Extrapolation of clinical trial results to clinical practice requires consideration of whether the trial patients were representative of clinical practice, whether the trial therapy studied was optimal, whether the sample size was adequate, and the impact of adjunctive treatments. In thrombolytic trials in particular, regional variations in attitudes to coronary angiography may have affected outcomes. Clinical trial results need to be interpreted in the light of the cost effectiveness of the application. The assessment of clinical outcomes depends on interplay between the structure and process of care, patient factors and chance. Large standardised databases are necessary to assess clinical practice and outcomes.

[Pharmacoeconomic evaluation of pravastatin in the secondary prevention of coronary heart disease in patients with average cholesterol levels. An analysis for Germany based on the CARE study]

Those people who are to decide about health care systems are increasingly forced to identify unnecessary costs and achieve savings in health care. Especially for diseases with high prevalence like illnesses of the heart and the circulatory system preventive measures are very important. This economic analysis tries to clarify whether the secondary-preventive application of the HMG-CoA reductase-inhibitor pravastatin is, apart from the clinical benefit, economically justified in patients suffering from coronary heart disease with average cholesterol levels. In the case of this study, the underlying type of economic evaluation was an incremental cost-effectiveness analysis. The outcome was defined as costs per life-year saved. This retrospective study is based on the results of the CARE (Cholesterol And Recurrent Events) study which has been published elsewhere [21]. When calculating costs we took into account the perspective of 3rd party payers (public health insurance) in Germany. The calculation of cost-effectiveness was carried out for the whole study population in CARE as well as for all patients aged 60 or more years in the CARE study. This was done because the different groups vary by the numbers of avoided myocardial infarctions, strokes and loss of life years. Netcosts for pravastatin therapy, i.e. drug costs for pravastatin minus costs for avoided events, were about 9.54 Mio DM (referring to 1,000 patients treated for a period of 5 years). Net-costs for patients aged 60 or more years were 8.18 Mio DM. The effectiveness was defined as the number of life years saved and amounted to 216 years of life saved (YOLS) in the overall study group. For patients aged 60 or more years we found that 358 years were saved. The costs per life years saved (i.e. the net-costs of pravastatin therapy divided through the number of life years saved) turned out to be 44,000 DM per person in the study group. For patients over 60 the costs were 23,000 DM. Lipid-lowering with pravastatin in the secondary prevention of coronary heart disease in Germany is cost-effective. In those patients aged 60 or more yeas the use of pravastatin is even more cost-effective than in all patients included in the CARE study.

Cardiac rehabilitation in the elderly

Rehabilitation for patients with heart disease consists of exercise training, behavioral interventions, counseling, and education with the goal of improving physiologic and psychosocial status. The Cardiac Rehabilitation Clinical Practice Guidelines, recently published in the United States, list the most substantial benefits of cardiac rehabilitation as an improvement in exercise tolerance, symptoms, blood lipid levels, and psychosocial well-being, and a reduction in cigarette smoking, stress, and mortality. With the evidence-base on the elderly in the Guidelines derived from 1 non-randomized controlled trial and 7 observational studies, the efficacy and effectiveness of cardiac rehabilitation is based almost exclusively on data generated on young and middle-aged males. We have located an additional 10 randomized and 2 non-randomized controlled trials published since the Guidelines, but only one provided age-specific data. The elderly are the fastest growing segment of the population, and may be more responsive to the effects of cardiac rehabilitation as they often have greater initial disability and less independence than younger patients. While referral of elderly persons to cardiac rehabilitation services appears safe and warranted in the secondary prevention of heart disease, the lack of rigorous scientific evidence has created an important clinical research and clinical policy vacuum which urgently needs to be filled.

Evidence-based medicine and cost-effectiveness analysis

Health care has become increasingly expensive and clinicians have come under increased scrutiny to critically appraise the economic impact of medical programs and interventions. To ensure an equitable allocation of scarce resources and the attainment of maximal clinical benefit, it is vital to adhere to certain basic tenets of economic analysis and to understand the basic approach to cost-effectiveness analysis. These principles are applied to critical care medicine and analogies are made to the methodological rigor of evidence-based medicine.

Thrombolytic therapy: a review of its use in acute myocardial infarction

OBJECTIVE

To review the literature on the use of thrombolytic agents in the pharmacotherapeutic management of acute myocardial infarction (AMI).

DATA SOURCE

English-language clinical trials, reviews, and editorials derived from MEDLINE (January 1966-September 1997) and/or cross-referencing of selected articles.

STUDY SELECTION

Articles that were selected best represent the clinical trials researching the role for thrombolytics in the therapy of AMI to improve morbidity and mortality.

DATA SYNTHESIS

AMI is one of the leading causes of mortality in the US. Following supportive data that the most common cause of an AMI is an intracoronary thrombus, clinical investigation has demonstrated that intravenous thrombolytic agents improve survival rates in patients who experience an AMI. Several clinical trials have been conducted to determine whether one thrombolytic agent is superior to others with respect to improving mortality. At present, only the first Global Use of Streptokinase and Tissue Plasminogen Activator for Occluded Coronary Arteries (GUSTO-I) trial has reported any statistically significant difference in mortality rate. In this trial, "front-loaded" alteplase induced a statistically significant (p < 0.001) 1% absolute reduction in 30-day and 1-year mortality compared with streptokinase. This has led to alteplase being the preferred thrombolytic at many US institutions. However, the results of GUSTO-I have been questioned by some on the basis of either study design or clinical significance.

CONCLUSIONS

Thrombolytic agents have secured a place in the treatment of AMI due to their well-proven reduction in mortality rates. In general, comparative trials have demonstrated minimal differences in efficacy among these agents. Probably just as important as choosing which thrombolytic agent to use is ensuring that a patient experiencing an AMI is administered thrombolytic therapy unless a contraindication to receive such therapy exists in the patient and/or the patient is a candidate to receive an emergent intracoronary procedure. Trials also indicate that the sooner thrombolytics can be administered, the greater the benefit to the patient.

Evaluating the cost-effectiveness of clinical and public health measures

Cost-effectiveness analysis, an analytic tool that expresses as a ratio the cost of obtaining an additional unit of health outcome, can help decision makers achieve more health protection for the same or less cost. We characterize the state of the cost-effectiveness analysis literature by reviewing how this technique is applied to various clinical and public health interventions. We describe the results of cost-effectiveness analyses for over 40 interventions to reduce cancer, heart disease, trauma, and infectious disease. The cost-effectiveness ratios for these interventions vary enormously, from interventions that save money to those that cost more than $1 million per year of life gained. The methods used to derive the cost-effectiveness ratios also vary considerably, and we summarize this variation within each health area. Greater uniformity of analytical practice will be necessary if cost-effectiveness analysis is to become a more influential tool in debates about resource allocation.

Toward consistency in cost-utility analyses: using national measures to create condition-specific values

OBJECTIVES

The authors developed an "off-the-shelf" source of health-related quality of life (HRQL) scores for cost-effectiveness analysts unable to collect primary data.

METHODS

The authors derived and conducted preliminary validation on a set of health-related quality of life scores for chronic conditions using nationally representative data from the National Health Interview Survey (NHIS) and the Healthy People 2000 Years of Healthy Life measure developed to monitor the health (longevity and health-related quality of life) of Americans during this decade. The measure comprises two domains, role function and self-rated health, and is scaled from 0 (death) to 1 (best health state). Health-related quality of life scores for chronic conditions were calculated using the Years of Healthy Life scores associated with chronic conditions reported in the 1987-1992 National Health Interview Survey. Preliminary validation was examined by comparing the health-related quality of life scores with those obtained in two other studies.

RESULTS

Tables provide health-related quality of life scores for persons with and without conditions. The scores had reasonable face validity, ranging from 0.87 for allergic rhinitis to 0.27 for hemiplegia. Correlations of the health-related quality of life condition weight scores with those from two other studies were 0.78 and 0.86.

CONCLUSIONS

These condition weights may prove useful to investigators conducting cost-effectiveness analyses using secondary data, where community ratings of health-related quality of life for chronic conditions are required. Use of a standard set of health-related quality of life weights gathered from a national sample can enhance the comparability of cost-effectiveness analyses. Improvements in national data collection techniques, with empirical gathering of preferences, will further strengthen this measure.