Warfarin for dilated cardiomyopathy: a bloody tough pill to swallow?

Cohort decomposition for Markov cost-effectiveness models

Cohort analysis is a widespread tool for computing expected costs and quality-adjusted life years (QALYs) in Markov models for medical cost-effectiveness analyses. Although not always explicitly identified, such models commonly have multiple simple factors, or components. In these, a health state consists of a multiple component vector, one component for each factor, and arbitrary combinations of components are possible. The authors show here that when the model does not assume any probabilistic dependence among these factors, then a standard cohort analysis may be decomposed into several independent cohort analyses, one for each factor, and the results may be combined to produce desired expected costs and QALYs. These single-factor cohort analyses are not only simpler but also computationally more efficient. The authors derive the appropriate formulas for this cohort decomposition in discrete time and give several examples of their use based on published cost-effectiveness analyses. Explicitly identifying the simple factors of which a model is composed allows these factors to be portrayed graphically. Graphical depiction of the simple factors that comprise a model reduces model complexity, makes model formulation easier and more transparent, and thereby facilitates peer inspection and critique.

Influence of warfarin on symptoms of fatigue: findings of a randomized trial

BACKGROUND

Some patients develop fatigue while taking warfarin, but causality is uncertain.

OBJECTIVE

To assess whether warfarin use is associated with fatigue.

METHODS

This investigation was a substudy of a randomized double-blind trial in 13 outpatient thromboembolism clinics. Subjects who had received one month of open-label warfarin therapy for venous thromboembolism due to a transient risk factor were randomly assigned to receive warfarin or placebo for 2 months and followed for another 9 months after stopping the study drug. Fatigue was measured using a Likert scale, and change of fatigue was measured by the patient's global rating.

RESULTS

In 87 subjects, the overall ratings of fatigue were 0.1 unit lower (95% CI 0.6 units lower to 0.4 units higher) while taking warfarin. Global rating for change in fatigue intensity showed no increase of fatigue with warfarin use.

CONCLUSIONS

The short-term use of warfarin was not associated with symptoms of fatigue.

Prophylaxis of thromboembolic events in congestive heart failure

In patients with heart failure the incidence of thromboembolism is 0.9-5.5%/year (mean 1.9%/year), but no randomized studies are available to support the indication for anticoagulant therapy in those patients. Atrial fibrillation and previous thromboembolic events seem to be the major risk factors, whereas the effect of ventricular dysfunction has not been independently evaluated; nonetheless several studies suggest that thromboembolism is more likely among those patients with lower ejection fraction and lower peak exercise oxygen consumption. Anticoagulant therapy seems to be indicated also in patients with left ventricular aneurysm with mobile and protruding thrombi. Several studies of patients with dilated cardiomyopathy show that the incidence of thromboembolism ranges from 1.6 to 4.5%/year in patients not treated with anticoagulants, while it is virtually absent in anticoagulated patients. The clinical opportunity of long-term anticoagulant treatment in heart failure patients should be weighted not only on the clinical markers of thromboembolic risk, but also on the relative risk/benefit ratio of the single patient.

[Evidence based medical treatment of heart failure]

INTRODUCTION AND OBJECTIVES

Recommendations for the treatment of heart failure were carried out by a systematic review of the available evidence of the different pharmacologic treatments.

MATERIAL AND METHODS

The review focused on the treatment of chronic and systolic heart failure. All the studies published in english about the pharmacologic treatment of heart failure where identified. The evidence of every pharmacologic treatment was classified according to: a) efficacy variables (reduction of mortality and hospitalizations, improvement of functional class, ejection fraction and exercise tolerance), and b) the level of quality of the evidence according to an evaluation scale. The evidence was also reviewed for the comparisons and the combinations of the pharmacologic treatments, as well as for the toxicity and costs of treatments.

RESULTS

The recommendations were defined according to the NYHA functional class and were classified in the A, B and C categories according to the level of quality of the available evidence. The evidence on mortality was considered the most important. First line drugs, the alternatives and other possible treatments were take into account.

CONCLUSIONS

There is enough evidence based on information about some variables such as reduction of mortality or hospitalizations to carry out treatment recommendations in all stages of heart failure. This point out the interest ant the priority of used them in the evaluation and improvement of the results of heart failure.

Carotid Doppler high-intensity transient signals in dilated cardiomyopathy

BACKGROUND

Thromboembolism is an infrequent but serious complication in dilated cardiomyopathy (DCM), and the role of primary preventive antithrombotic or anticoagulation therapy is undetermined. High-intensity transient signals (HITS) by Doppler ultrasound representing microemboli have been described in various clinical settings associated with increased risk of stroke. This study assessed the feasibility, reproducibility, and prevalence of HITS in patients with DCM.

METHODS

Thirty patients with severely reduced left ventricular ejection fraction (< or = 35%, mean 25%) and New York Heart Association class II to III who were not receiving antithrombotic or anticoagulant therapy and 20 age-matched normal subjects were prospectively examined. Patients with atrial fibrillation, significant cardiac valvular heart disease, a history of cerebrovascular disease, and those who otherwise required antithrombotic or anticoagulation therapy were excluded. One-hour pulsed-wave Doppler recordings over the common carotid artery (CCA) were performed on 3 separate days in each subject by a single, experienced, blinded sonographer with a 4-MHz probe (TC-2000, Nicolet/EME) with a specially designed probe holder. Studies were read in a blinded, random fashion by 2 independent, experienced HITS Doppler recording readers.

RESULTS

HITS in the CCA were detected in 6 (20%) of 30 patients with DCM and in 3 (15%) of 20 volunteers. This difference was not statistically significant. Intrareader and interreader reproducibility were high (kappa = 0.91 and 0.84, respectively; P <.001), whereas intrasubject reproducibility over the 3 visits was moderate to low (kappa = 0.22). There was no significant difference between HITS characteristics, that is, intensity and duration, in patients versus controls.

CONCLUSIONS

The prevalence of CCA HITS in patients with clinically stable heart failure who are not receiving anticoagulation/antithrombotic therapy and are not in atrial fibrillation is low and not significantly different from normal patients. These data suggest that HITS monitoring is not a viable surrogate marker for increased thromboembolic risk in such patients with DCM.

The cost-effectiveness of different management strategies for patients on chronic warfarin therapy

OBJECTIVE

To examine the cost-effectiveness of moving from usual care to more organized management strategies for patients on chronic warfarin therapy.

DESIGN

Using information available in the scientific literature, supplemented with data from a large health system and, when necessary, expert opinion, we constructed a 5-year Markov model to evaluate the health and economic outcomes associated with each of three different anticoagulation management approaches: usual care, anticoagulation clinic testing with a capillary monitor, and patient self-testing with a capillary monitor.

PATIENTS

Three hypothetical cohorts of patients beginning long-term warfarin therapy were used to generate model results.

MAIN RESULTS

Model results indicated that moving from usual care to anticoagulation clinic testing would result in a total of 1.7 thromboembolic events and 2.0 hemorrhagic events avoided per 100 patients over 5 years. Another 4.0 thromboembolic events and 0.8 hemorrhagic events would be avoided by moving to patient self-testing. When direct medical care costs and those incurred by patients and their caregivers in receiving care were considered, patient self-testing was the most cost-effective alternative, resulting in an overall cost saving.

CONCLUSIONS

Results illustrate the potential health and economic benefits of organized care management approaches and capillary monitors in the management of patients receiving warfarin therapy.

Quality of life after cerebrovascular stroke: a systematic study of patients' preferences for different functional outcomes

OBJECTIVES

To elicit valid quality of life estimates and the highest acceptable treatment risk of different outcomes after stroke. This is a prerequisite for rational medical decision-making, especially when considering treatments like thrombolysis.

SUBJECTS

Healthy people, non-stroke medical patients and stroke survivors aged 20-84 years (n = 158)

INTERVENTIONS

Subjects were interviewed by a physician using three different methods ('standard gamble', 'time trade-off' and 'direct scaling') supported by an interactive computer program.

MAIN OUTCOME MEASURES

We measured utility, a numerical value ranging from 0.00 (death) to 1.00 (perfect health), representing the strength of the patient's preference for an outcome. When using the standard gamble method, risk is also introduced into the measurement.

RESULTS

People's preferences for stroke outcomes varied widely, and the estimates were influenced by assessment method. We found that previous stroke, marital status and age were the only independent variables influencing the utility given. Subjects in our population over the age of 45 were very comparable to the real population at risk for acute stroke regarding these three variables, and they assigned a median utility of 0.91 (10th percentile, 0.65; 90th percentile, 0.99) to a minor stroke and 0.61 (10th percentile, 0.08; 90th percentile, 0.95) to a major stroke using the standard gamble method.

CONCLUSIONS

Most people do not feel that suffering from stroke is an overwhelming catastrophe and they do not accept treatment options with very high risks.

Intracardiac thrombus formation in cardiac impairment: the role of anticoagulant therapy

The presence of intracardiac thrombus has been associated with many diseases and clinical states, although cardiac impairment is commonly also present. Despite this, there continues to be a lack of consensus on which patients with cardiac impairment should have anticoagulant therapy. This review discusses the relationship between thromboembolism and cardiac impairment secondary to ischaemic heart disease, and suggests possible mechanisms, methods of diagnosis and therapeutic strategies for anticoagulation in such patients. In particular, warfarin has been established as thromboprophylaxis in certain subgroups of patients with cardiac impairment secondary to ischaemic heart disease. A large-scale randomised controlled trial in ambulant patients with cardiac impairment to evaluate the effectiveness of anticoagulant therapy and antiplatelet therapy is, however, long overdue.

Therapeutic strategies for atrial fibrillation. The value of decision analysis

In the absence of randomized, controlled trials of low-dose amiodarone in atrial fibrillation or a randomized, controlled trial of ventricular rate control versus antifibrillatory therapy, a Markov decision analysis is useful in comparing different therapeutic strategies for atrial fibrillation. The decision analysis described compared warfarin, quinidine, and low-dose amiodarone in patients with asymptomatic or minimally symptomatic chronic, persistent atrial fibrillation. This model suggests that electrical cardioversion followed by low-dose amiodarone is a relatively safe, effective alternative to long-term warfarin therapy.

Decision analysis in the clinical neurosciences: a systematic review of the literature

Clinical decision analysis can be a useful scientific tool for individual patient management, for planning of clinical research and for reaching consensus about clinical problems. We systematically reviewed the decision analytic studies in the clinical neurosciences that were published between 1975 and July 1994. All studies were assessed on aspects of clinical applicability: presence of case and context description, completeness of the analysed strategies from a clinical point of view, extendibility of the analyses to different patient profiles, and up-to-date-ness. Fifty-nine decision analyses of twenty-eight different clinical problems were identified. Twenty-eight analyses were based on the theory of subjective expected utility, twelve on cost-effectiveness analysis. Four studies used ROC analysis, and fifteen were risk-, or risk-benefit analyses. At least six studies could have been improved by more elaborately disclosing the context of the clinical problem that was addressed. In eleven studies, the effect of different, yet plausible assumptions was not explored, and in eighteen studies the reader was not informed how to extend the results of the analysis to patients with (slightly) different clinical characterisitics. All studies had, by nature, the potential to promote insight into the clinical problem and focus the discussion on clinically important aspects, and gave clinically useful advice. We conclude that clinical decision analysis, as an explicit, quantitative approach to uncertainty in decision making in the clinical neurosciences will fulfill a growing need in the near future.

Determinants of the optimal time in gestation to initiate antenatal fetal testing: a decision-analytic approach

To identify the most important determinants of the optimal timing for the initiation of antenatal fetal testing in a high-risk pregnancy (such as insulin-dependent diabetes mellitus), we performed a decision analysis based on a Markov model. The model incorporated several components: test sensitivity and specificity and week-specific probability estimates for fetal death, delivery, and neonatal morbidity and mortality. The analysis demonstrated that the optimal time in gestation to begin testing (from the combined standpoint of both maximizing neonatal survival and minimizing fetal death) was highly dependent on test specificity, the cumulative risk of fetal death (and its distribution throughout gestation), and the week-specific probabilities of neonatal death. For example, even with the increased risk of fetal death associated with insulin-dependent diabetes, very high test specificity (> 99%) is required to recommend testing before 30 weeks. If tests of lower specificity (higher false-positive rates) are used, neonatal deaths will increase and will not be offset by a corresponding decrease in fetal deaths. By performing sensitivity analyses, we demonstrated the effect and relative importance of the model components for determining the optimal gestational age to initiate fetal testing.

Cost-effectiveness of captopril therapy after myocardial infarction

OBJECTIVES

This study sought to assess the cost-effectiveness of captopril therapy for survivors of myocardial infarction.

BACKGROUND

The recent randomized, controlled Survival and Ventricular Enlargement (SAVE) trial showed that captopril therapy improves survival in survivors of myocardial infarction with an ejection fraction < or = 40%. The present ancillary study was designed to determine how the costs required to achieve this increase in survival compared with those of other medical interventions.

METHODS

We developed a decision-analytic model to assess the cost-effectiveness of captopril therapy in 50- to 80-year old survivors of myocardial infarction with an ejection fraction < or = 40%. Data on costs, utilities (health-related quality of life weights) and 4-year survival were obtained directly from the SAVE trial, and long-term survival was estimated using a Markov model. In one set of analyses, we assumed that the survival benefit associated with captopril therapy would persist beyond 4 years (persistent-benefit analyses), whereas in another set we assumed that captopril therapy incurred costs but no survival benefit beyond 4 years (limited-benefit analyses).

RESULTS

In the limited-benefit analyses, the incremental cost-effectiveness of captopril therapy ranged from $3,600/quality-adjusted life-year for 80-year old patients to $60,800/quality-adjusted life-year for 50-year old patients. In the persistent-benefit analyses, incremental cost-effectiveness ratios ranged from $3,700 to $10,400/quality-adjusted life-year, depending on age. The outcome was generally not sensitive to changes in estimates of variables when they were varied individually over wide ranges. In a "worst-case" analysis, incremental cost-effectiveness ratios for captopril therapy remained favorable ($8,700 to $29,200/quality-adjusted life-year) for 60- to 80-year old patients but were higher ($217,600/quality-adjusted life-year) for 50-year old patients.

CONCLUSIONS

We conclude that the cost-effectiveness of captopril therapy for 50- to 80-year old survivors of myocardial infarction with a low ejection fraction compares favorably with other interventions for survivors of myocardial infarction.

Prophylactic oral anticoagulation in nephrotic patients with idiopathic membranous nephropathy

Whether the high incidence of thromboembolic events in nephrotic patients with membranous nephropathy justifies prophylactic administration of oral anticoagulants remains controversial. We used a Markov-based decision analysis model, explicitly considering the consequences of recurrent embolic and bleeding events to quantify the risk-benefit trade-offs of: (1) prophylactic therapy, in which oral anticoagulation was started at the time of diagnosis of nephrotic syndrome (before any thromboembolic event); and (2) anticoagulant therapy, in which treatment was started after the first clinical thromboembolic event. We assumed that anticoagulant therapy was discontinued if there was remission of the nephrotic syndrome. The overall number of fatal emboli prevented by prophylactic anticoagulants exceeded the one of fatal bleeding events for all clinically meaningful ranges of the following parameters: nephrotic syndrome duration, incidence of thromboembolic events, likelihood of embolization, and mortality rates of embolic and bleeding events. For a hypothetical 50-year-old patient who remained nephrotic for 2 years, prophylactic anticoagulation yielded a gain representing 2.5 months of quality-adjusted life expectancy. We conclude that for nephrotic patients with membranous nephropathy, the benefits of prophylactic administration or oral anticoagulants outweigh the risks.

Management and prevention of thromboembolic events in patients with cancer-related hypercoagulable states: a risky business

OBJECTIVE

To determine the optimal strategy for managing and preventing thromboembolic events in malignancy-associated hypercoagulable states.

DESIGN

A Markov-based decision and cost-effectiveness analysis was performed. The authors explicitly considered consequences of embolic and bleeding events, filter complications, and cancer-related excess mortality. Data were drawn from the current literature. The main outcome measure for each strategy was the quality-adjusted life expectancy and the total average variable costs.

SUBJECTS

Patients with advanced malignancies prone to develop thromboembolic events, patients with acute proximal deep venous thrombosis (DVT), and patients who have survived a first episode of pulmonary embolism (PE).

INTERVENTIONS

The authors considered three different interventions: 1) OBSERVATION, in which neither anticoagulant therapy nor filter placement is pursued, 2) ANTICOAGULATION, in which long-term anticoagulant therapy is started immediately, and 3) VENA CAVAL FILTER.

MAIN RESULTS

Vena caval filter was the preferred strategy for every malignancy studied, yielding an 11% gain in quality-adjusted life expectancy, compared with observation, for patients with acute DVT, and an 18% gain for patients having survived a PE. Anticoagulant therapy yielded gains of 9% and 16%, respectively. Compared with anticoagulant therapy, filter was less costly due to the avoidance of additional expenses incurred by bleeding events. Prophylactic therapy was the least effective of the three strategies examined.

CONCLUSIONS

Vena caval filter placement and long-term anticoagulation therapy yield similar outcomes in the setting of cancer-related hypercoagulable states. However, filter insertion is less expensive than anticoagulation. Given the short life expectancy and morbidity of patients with end-stage malignancy, patient preferences for health states must be considered in the decision-making process. If active treatment is pursued, vena caval filter should be used as a primary therapy. Prophylactic therapy is not warranted in any circumstance.

Factored stochastic trees: a tool for solving complex temporal medical decision models

The stochastic tree is a continuous-time version of a Markov-cycle tree, useful for constructing and solving medical decision models in which risks of mortality and morbidity may extend over time. Stochastic trees have advantages over Markov-cycle trees in graphic display and computational solution. Like the decision tree or Markov-cycle tree, stochastic tree models of complex medical decision problems can be too large for convenient graphic formulation and display. This paper introduces the notion of factoring a large stochastic tree into simpler components, each of which may be easily displayed. It also shows how the rollback solution procedure for unfactored stochastic trees may be conveniently adapted to solve factored trees. These concepts are illustrated using published examples from the medical literature.

Atrial fibrillation and anticoagulation: from randomised trials to practice

Randomised trials confirm that anticoagulants reduce the risk of emboli in atrial fibrillation. To apply this evidence to practice, we developed an expression relating all relevant factors. Trial-based estimates of the risks of emboli and haemorrhage, and of the effects of anticoagulants on these risks were used to derive the extent to which haemorrhage has to be seen to be more detrimental than emboli to justify not using anticoagulants. Information from other studies was used to assess the risks for the types of patients not included in the trials. Haemorrhage needs to be assessed as being at least six times more detrimental than emboli to warrant withholding anticoagulants from patients like those in the trials. Only in patients with lone atrial fibrillation and in those with features suggesting a bleeding risk six times higher than the trials' average would a perception of equal detriment risk justify not giving anticoagulation.

Decision analysis--a helpful tool for clinicians to establish diagnostic-therapeutic guidelines?

In this paper we focus on the question: Does decision analysis provide a framework to assess the value of diagnostic tests in clinical practice and how can it be used by clinicians in establishing diagnostic-therapeutic guidelines. To study this question we performed two analyses concerning the use of pelvic lymphadenectomy and pedal lymphography for staging prostate cancer. Both analyses yielded similar results as far as the preferred strategy was concerned, yet the approach and set up of the two analyses were different. The first analysis was performed in accordance with the textbooks on decision analysis. However, using this traditional approach we encountered some difficulties: in structuring the decision tree, in eliciting values for the quality of life parameters, and in interpreting the results. These difficulties urged us to modify the approach, presented in the second analysis. In this second analysis, the decision problem was split into several consecutive decision problems which corresponded to the questions posed by the clinicians. Longevity and quality of life were considered separately and the consequences of treatment and testing, which affect the quality of life of the patients, were indicated by just two parameters. Finally, the result of the analysis was expressed in clinically meaningful terms. The second analysis is compared with different approaches presented in the literature for analyzing decision problems involving diagnostic tests. Despite some unresolved methodological problems it is concluded that decision analysis provides a good framework for clinicians to structure and analyze complex decision problems.

Treatment of chronic nonvalvular atrial fibrillation in the elderly: a decision analysis

The objective of the study was to determine the preferred treatment strategy for elderly patients with chronic nonvalvular atrial fibrillation (CNVAF). A Markov decision-analytic model was used to compare three treatment strategies for CNVAF: 1) warfarin; 2) aspirin; and 3) no treatment. Five-year quality-adjusted life years (QALYs) were calculated for male and female cohorts aged 70 and 75 years. In the baseline analysis (effectiveness of warfarin = 0.70, effectiveness of aspirin = 0.45, utility of warfarin = 0.99, and utility of aspirin = 0.999) the quality-adjusted survival rates for 70-year-old males were 4.03 QALYs on warfarin, 4.02 QALYs on aspirin, and 3.95 QALYs on no treatment. Results were similar for all age and sex cohorts. Sensitivity analyses revealed that the results were very sensitive to the effectiveness of aspirin and the disutility of warfarin. The authors conclude that the optimal strategy for the treatment of CNVAF in elderly patients varies with the disutility assigned to warfarin therapy and the effectiveness value for aspirin therapy.

Stochastic trees: a new technique for temporal medical decision modeling

This paper introduces stochastic trees, a new modeling approach for the class of medical decision problems in which risks of mortality and morbidity may extend over time. A stochastic tree may be regarded as a continuous-time version of a Markov-cycle tree, or alternately, as a multi-state DEALE model. Optimal decisions in stochastic trees can be determined by rollback, much in the same fashion as decision trees. The author discusses how age-dependent mortality rates and declining incidence rates may be modeled using stochastic trees. Concepts are illustrated using examples from the medical literature. It is argued that stochastic trees possess important advantages over Markov-cycle trees for medical decision modeling.

Should all patients with atrial fibrillation be screened with echocardiography?

OBJECTIVE

To address a patient care problem suggested by a quality assurance study: Should physicians of patients with atrial fibrillation who have not had echocardiography performed be encouraged to obtain echocardiograms in order to discover heretofore undetected mitral stenosis, which could be treated with anticoagulation, in order to avert strokes?

DESIGN

Decision analysis using a Markov-chain technique and quality-adjusted life expectancy.

SETTING

Outpatient clinics.

PATIENTS

Patients aged 40-80 years with chronic atrial fibrillation.

INTERVENTIONS

The following strategies were studied: 1) obtain echocardiograms for all patients and anticoagulate those with mitral stenosis; 2) anticoagulate patients with classic auscultatory sounds of mitral stenosis and obtain echocardiograms for patients with other murmurs; if an echocardiogram reveals mitral stenosis, anticoagulate; 3) anticoagulate all patients with murmurs; 4) anticoagulate all patients; 5) observe all patients (natural history).

MAIN RESULTS

The base analysis, using data available in the literature and on site, indicated that though performing echocardiography on all patients with atrial fibrillation gave the best quality-adjusted life expectancy, the differences among the five strategies studied were small. In addition, sensitivity analysis revealed that the decision was sensitive to many of the variables used in the analysis, especially the efficacy and the risks of anticoagulation.

CONCLUSION

A recommendation that cardiac ultrasonography be done for all patients with atrial fibrillation in order to detect clinically unrecognized mitral stenosis cannot be made.

Acute pulmonary embolism in pediatric patients awaiting heart transplantation

Acute pulmonary embolism with infarction can delay urgently needed heart transplantation and increase the postoperative pulmonary complications. Few data are available concerning pulmonary embolization in the pediatric patient with end-stage congestive heart failure. Sixty-two consecutive pediatric patients awaiting heart transplantation were monitored for evidence of acute pulmonary embolism. Acute pulmonary infarction was documented by ventilation-perfusion scan, pulmonary angiography or pathologic examination in six patients. The prevalence differed by diagnosis; 5 of 36 patients with dilated cardiomyopathy and 1 of 20 patients with congenital heart disease developed acute pulmonary embolism with infarction. No significant difference in age at the time of transplantation evaluation, duration of congestive heart failure, presence of cardiac arrhythmias or degree of cardiac dysfunction was seen between patients with and without pulmonary embolism. Two-dimensional echocardiography failed to detect the presence of an intracardiac thrombus in four of the six patients. Two patients who developed acute pulmonary infarction are alive after successful heart transplantation. The remaining four patients died within 6 weeks of initiation of anticoagulant therapy before transplantation could safely be performed. In summary, pediatric patients with end-stage congestive heart failure are at risk for acute pulmonary embolism. No specific clinical factor identified those patients who developed acute pulmonary infarction. Anticoagulant therapy is strongly recommended in the pediatric patient with poor ventricular function awaiting heart transplantation.

Efficacy and cost effectiveness of adjuvant chemotherapy in women with node-negative breast cancer. A decision-analysis model

BACKGROUND

In 1988 the National Cancer Institute issued a Clinical Alert that has been widely interpreted as recommending that all women with node-negative breast cancer receive adjuvant chemotherapy. Acceptance of this recommendation is controversial, since many women who would not have a recurrence would be treated.

METHODS

Using a decision-analysis model, we studied the cost effectiveness of chemotherapy in cohorts of 45-year-old and 60-year-old women with node-negative breast cancer by calculating life expectancy as adjusted for quality of life. The analysis evaluated different scenarios of the benefit of therapy: improved disease-free survival for five years, with a lesser effect on overall survival (base line); a lifelong benefit from chemotherapy; and a benefit in disease-free survival with no change in overall survival by year 10. The base-line analysis assumed a 30 percent reduction in the relative risk of recurrence for five years after treatment.

RESULTS

For the 45-year-old woman, the base-line analysis found an average lifetime benefit from chemotherapy of 5.1 quality-months at a cost of $15,400 per quality-year. The 60-year-old women gained 4.0 quality-months at a cost of $18,800 per quality-year. Under the more and less optimistic scenarios, the benefit of chemotherapy varied from 1.4 to 14.0 quality-months for both groups.

CONCLUSIONS

Chemotherapy substantially increases the quality-adjusted life expectancy of an average woman at a cost comparable to that of other widely accepted therapies. This benefit decreases markedly if the changes in long-term survival are less than in disease-free survival. Given its uncertain duration, the benefit may be too small for many women to choose chemotherapy. Selective use of chemotherapy to maximize the benefit to individual patients may be possible with refinements in risk stratification and explicit assessment of the patients' risk preferences.

Management of asymptomatic chronic aortic regurgitation with left ventricular dysfunction: a decision analysis

STUDY OBJECTIVE

To determine the optimal strategy for the timing of aortic valve replacement in patients with chronic, severe aortic regurgitation with left ventricular dysfunction.

DESIGN

Decision analysis comparing early surgery (timed at the onset of left ventricular dysfunction) with delayed surgery (timed at the onset of symptoms) using data from the literature and expert opinion for variables in a representative case scenario (40-year-old man with bicuspid aortic valve disease).

SETTING

Tertiary care center doing valve replacement surgery.

MEASUREMENTS AND MAIN RESULTS

The early-surgery approach was preferred based on quality-adjusted life years. Sensitivity analysis showed that the result was not affected by the following variables within their derived ranges: rate of symptom development after onset of left ventricular dysfunction for the delayed-surgery approach, perioperative mortality for both approaches, and occurrence of major nonfatal stroke or congestive heart failure for both approaches. Although the decision was sensitive to the yearly postoperative mortality rates, the delayed-surgery operative mortality rate had to be almost as low as the early-surgery rate to change the preference to the delayed-surgery approach. The preference could also change if survival were much more important to the patient in the first five years than after five years or if the patient disliked living on anticoagulants enough to value a year on anticoagulants as worth only 80% of a year not on anticoagulants.

CONCLUSION

This decision analysis provides quantitative support for the impression that patients similar to the case scenario do better with surgery timed at the onset of ventricular dysfunction than with surgery delayed until symptoms develop. It thus supports the practice of following these patients noninvasively in order to time surgery.