Biomedical subjects

G D Sanders

Publications and source records attributed to G D Sanders.

At least 19 recordsLinked to original sources

PubMed2001

Potential cost-effectiveness of prophylactic use of the implantable cardioverter defibrillator or amiodarone after myocardial infarction.

BACKGROUND: Clinical trials have shown that implantable cardioverter defibrillators (ICDs) improve survival in patients with sustained ventricular arrhythmias. OBJECTIVE: To determine the efficacy necessary to make prophylactic ICD or amiodarone therapy cost-effective in patients with myocardial infarction. DESIGN: Markov model-based cost utility analysis. DATA SOURCES: Survival, cardiac death, and inpatient costs were estimated on the basis of the Myocardial Infarction Triage and Intervention registry. Other data were derived from the literature. TARGET POPULATION: Patients with past myocardial infarction who did not have sustained ventricular arrhythmia. TIME HORIZON: Lifetime. PERSPECTIVE: Societal. INTERVENTIONS: ICD or amiodarone compared with no treatment. OUTCOME MEASURES: Life-years, quality-adjusted life-years (QALYs), costs, number needed to treat, and incremental cost-effectiveness. RESULTS OF BASE-CASE ANALYSIS: Compared with no treatment, ICD use led to the greatest QALYs and the highest expenditures. Amiodarone use resulted in intermediate QALYs and costs. To obtain acceptable cost-effectiveness thresholds (</=$75,000/QALY), ICDs had to reduce arrhythmic death by 50% and amiodarone had to reduce total death by 7% in patients with depressed ejection fraction. RESULTS OF SENSITIVITY ANALYSIS: For moderate efficacies, in patients with ejection fractions less than or equal to 0.3, 0.31 to 0.4, and greater than 0.4, the cost-effectiveness of amiodarone compared with no therapy was $43,100/QALY, $66,500/QALY, and $132,500/QALY, respectively, and the cost-effectiveness of ICD compared with amiodarone was $71,800/QALY, $195,700/QALY, and $557,900/QALY, respectively. CONCLUSIONS: Use of ICD or amiodarone in patients with past myocardial infarction and severely depressed left ventricular function may provide substantial clinical benefit at an acceptable cost. These results highlight the importance of clinical trials of ICDs in patients with low ejection fractions who have had myocardial infarction.

Adult↗

PubMed2001

Cost-effectiveness of automated external defibrillators on airlines.

CONTEXT: Installation of automated external defibrillators (AEDs) on passenger aircraft has been shown to improve survival of cardiac arrest in that setting, but the cost-effectiveness of such measures has not been proven. OBJECTIVE: To examine the costs and effectiveness of several different options for AED deployment in the US commercial air transportation system. DESIGN, SETTING, AND SUBJECTS: Decision and cost-effectiveness analysis of a strategy of full deployment on all aircraft as well as several strategies of partial deployment only on larger aircraft, compared with a baseline strategy of no AEDs on aircraft (but training flight attendants in basic life support) for a hypothetical cohort of persons experiencing cardiac arrest aboard US commercial aircraft. Estimates for costs and outcomes were obtained from the medical literature, the Federal Aviation Administration, the Air Transport Association of America, a population-based cohort of Medicare patients, AED manufacturers, and the Bureau of Labor Statistics. MAIN OUTCOME MEASURES: Quality-adjusted survival after cardiac arrest; costs of AED deployment on aircraft and of medical care for cardiac arrest survivors. RESULTS: Adding AEDs on passenger aircraft with more than 200 passengers would cost $35 300 per quality-adjusted life-year (QALY) gained. Additional AEDs on aircraft with capacities between 100 and 200 persons would cost an additional $40 800 per added QALY compared with deployment on large-capacity aircraft only, and full deployment on all passenger aircraft would cost an additional $94 700 per QALY gained compared with limited deployment on aircraft with capacity greater than 100. Sensitivity analyses indicated that the quality of life, annual mortality rate, and the effectiveness of AEDs in improving survival were the most influential factors in the model. In 85% of Monte Carlo simulations, AED placement on large-capacity aircraft produced cost-effectiveness ratios of less than $50 000 per QALY. CONCLUSION: The cost-effectiveness of placing AEDs on commercial aircraft compares favorably with the cost-effectiveness of widely accepted medical interventions and health policy regulations, but is critically dependent on the passenger capacity of the aircraft. Placing AEDs on most US commercial aircraft would meet conventional standards of cost-effectiveness.

Aircraft↗

PubMed2001

Publishing web-based guidelines using interactive decision models.

Commonly used methods for guideline development and dissemination do not enable developers to tailor guidelines systematically to specific patient populations and update guidelines easily. We developed a web-based system, ALCHEMIST, that uses decision models and automatically creates evidence-based guidelines that can be disseminated, tailored and updated over the web. Our objective was to demonstrate the use of this system with clinical scenarios that provide challenges for guideline development. We used the ALCHEMIST system to develop guidelines for three clinical scenarios: (1) Chlamydia screening for adolescent women, (2) antiarrhythmic therapy for the prevention of sudden cardiac death; and (3) genetic testing for the BRCA breast-cancer mutation. ALCHEMIST uses information extracted directly from the decision model, combined with the additional information from the author of the decision model, to generate global guidelines. ALCHEMIST generated electronic web-based guidelines for each of the three scenarios. Using ALCHEMIST, we demonstrate that tailoring a guideline for a population at high-risk for Chlamydia changes the recommended policy for control of Chlamydia from contact tracing of reported cases to a population-based screening programme. We used ALCHEMIST to incorporate new evidence about the effectiveness of implantable cardioverter defibrillators (ICD) and demonstrate that the cost-effectiveness of use of ICDs improves from $74 400 per quality-adjusted life year (QALY) gained to $34 500 per QALY gained. Finally, we demonstrate how a clinician could use ALCHEMIST to incorporate a woman's utilities for relevant health states and thereby develop patient-specific recommendations for BRCA testing; the patient-specific recommendation improved quality-adjusted life expectancy by 37 days. The ALCHEMIST system enables guideline developers to publish both a guideline and an interactive decision model on the web. This web-based tool enables guideline developers to tailor guidelines systematically, to update guidelines easily, and to make the underlying evidence and analysis transparent for users.

Adolescent↗

PubMed2000

Cost-effectiveness of radiofrequency ablation for supraventricular tachycardia.

BACKGROUND: Radiofrequency ablation is an established but expensive treatment option for many forms of supraventricular tachycardia. Most cases of supraventricular tachycardia are not life-threatening; the goal of therapy is therefore to improve the patient's quality of life. OBJECTIVE: To compare the cost-effectiveness of radiofrequency ablation with that of medical management of supraventricular tachycardia. DESIGN: Markov model. DATA SOURCES: Costs were estimated from a major academic hospital and the literature, and treatment efficacy was estimated from reports from clinical studies at major medical centers. Probabilities of clinical outcomes were estimated from the literature. To account for the effect of radiofrequency ablation on quality of life, assessments by patients who had undergone the procedure were used. TARGET POPULATION: Cohort of symptomatic patients who experienced 4.6 unscheduled visits per year to an emergency department or a physician's office while receiving long-term drug therapy for supraventricular tachycardia. TIME HORIZON: Patient lifetime. PERSPECTIVE: Societal. INTERVENTIONS: Initial radiofrequency ablation, long-term antiarrhythmic drug therapy, and treatment of acute episodes of arrhythmia with antiarrhythmic drugs. OUTCOME MEASURES: Costs, quality-adjusted life-years, life-years, and marginal cost-effectiveness ratios. RESULTS OF BASE-CASE ANALYSIS: Among patients who have monthly episodes of supraventricular tachycardia, radiofrequency ablation was the most effective and least expensive therapy and therefore dominated the drug therapy options. Radiofrequency ablation improved quality-adjusted life expectancy by 3.10 quality-adjusted life-years and reduced lifetime medical expenditures by $27 900 compared with long-term drug therapy. Long-term drug therapy was more effective and had lower costs than episodic drug therapy. RESULTS OF SENSITIVITY ANALYSIS: The findings were highly robust over substantial variations in assumptions about the efficacy and complication rate of radiofrequency ablation, including analyses in which the complication rate was tripled and efficacy was decreased substantially. CONCLUSIONS: Radiofrequency ablation substantially improves quality of life and reduces costs when it is used to treat highly symptomatic patients. Although the benefit of radiofrequency ablation has not been studied in less symptomatic patients, a small improvement in quality of life is sufficient to give preference to radiofrequency ablation over drug therapy.

Adult↗

PubMed1999

Low-molecular-weight heparins compared with unfractionated heparin for treatment of acute deep venous thrombosis. A cost-effectiveness analysis.

BACKGROUND: Low-molecular-weight heparins are effective for treating venous thrombosis, but their cost-effectiveness has not been rigorously assessed. OBJECTIVE: To evaluate the cost-effectiveness of low-molecular-weight heparins compared with unfractionated heparin for treatment of acute deep venous thrombosis. DESIGN: Decision model. DATA SOURCES: Probabilities for clinical outcomes were obtained from a meta-analysis of randomized trials. Cost estimates were derived from Medicare reimbursement and other sources. TARGET POPULATION: Two hypothetical cohorts of 60-year-old men with acute deep venous thrombosis. TIME HORIZON: Patient lifetime. PERSPECTIVE: Societal. INTERVENTION: Fixed-dose low-molecular-weight heparin or adjusted-dose unfractionated heparin. OUTCOME MEASURES: Costs, quality-adjusted life-years (QALYs), and incremental cost-effectiveness ratios. An in-patient hospital setting was used for the base-case analysis. Secondary analyses examined outpatient treatment with low-molecular-weight heparin. RESULTS OF BASE-CASE ANALYSIS: Total costs for inpatient treatment were $26,516 for low-molecular-weight heparin and $26,361 for unfractionated heparin. The cost of initial care was higher in patients who received low-molecular-weight heparin, but this was partly offset by reduced costs for early complications. Low-molecular-weight heparin treatment increased quality-adjusted life expectancy by approximately 0.02 years. The incremental cost-effectiveness of inpatient low-molecular-weight heparin treatment was $7820 per QALY gained. Treatment with low-molecular-weight heparin was cost saving when as few as 8% of patients were treated at home. RESULTS OF SENSITIVITY ANALYSIS: When late complications were assumed to occur 25% less frequently in patients who received unfractionated heparin, the incremental cost-effectiveness ratio increased to almost $75,000 per QALY gained. When late complications were assumed to occur 25% less frequently in patients who received low-molecular-weight heparin, this treatment resulted in a net cost savings. Inpatient low-molecular-weight heparin treatment became cost saving when its pharmacy cost was reduced by 31% or more, when it reduced the yearly incidence of late complications by at least 7%, when as few as 8% of patients were treated entirely as outpatients, or when at least 13% of patients were eligible for early discharge. CONCLUSIONS: Low-molecular-weight heparins are highly cost-effective for inpatient management of venous thrombosis. This treatment reduces costs when small numbers of patients are eligible for outpatient management.

Anticoagulants↗

PubMed1999

Evaluation of genetic tests: APOE genotyping for the diagnosis of Alzheimer disease.

Many studies have now confirmed the association between inheritance of the epsilon 4 allele of the apolipoprotein E (APOE) gene and Alzheimer disease (AD). However, although the medical community holds the near-unanimous opinion that APOE genotyping should not be used for prediction in asymptomatic individuals, controversy remains about whether it should be used for diagnosis in patients who show signs of dementia. We assessed critically the recent clinical studies, on the basis of four criteria recommended to ensure safety and effectiveness of genetic tests. We also developed a formal framework for evaluating the usefulness of APOE genotyping using decision-theoretic principles. We conclude that neither the presence nor absence of an epsilon 4 allele provides diagnostic certainty, and the proper interpretation of either result in heterogeneous populations requires further investigation. The appropriate role of APOE genotyping among elements of a traditional assessment for AD has not been determined. Whether APOE genotyping provides sufficient information to change patient management decisions has not been determined. APOE genotyping presents foreseeable, significant psychosocial consequences for family members that must be weighed against any psychosocial benefits. Therefore, the diagnostic use of APOE genotyping outside research settings is premature until such testing is shown to be of practical value.

Alzheimer Disease↗

PubMed1998

Design of a modular, extensible decision support system for arrhythmia therapy.

We developed a decision-support system for evaluation of treatment alternatives for supraventricular and ventricular arrhythmias. The system uses independent decision models that evaluate the costs and benefits of treatment for recurrent atrioventricular-node reentrant tachycardia (AVNRT), and of therapies to prevent sudden cardiac death (SCD) in patients at risk for life-threatening ventricular arrhythmias. Each of the decision models is accessible through a web-based interface that enables remote users to browse the model's underlying evidence and to perform analyses of effectiveness, cost effectiveness, and sensitivity to input variables. Because the web-based interface is independent of the models, we can extend the functionality of the system by adding decision models. This system illustrates that the use of a library of web-accessible decision models provides decision support economically to widely dispersed users.

Arrhythmias, Cardiac↗

PubMed1997

Monitored isoniazid prophylaxis for low-risk tuberculin reactors older than 35 years of age: a risk-benefit and cost-effectiveness analysis.

BACKGROUND: Isoniazid chemoprophylaxis effectively prevents the development of active infectious tuberculosis. Current guidelines recommend withholding this prophylaxis for low-risk tuberculin reactors older than 35 years of age because of the risk for fatal isoniazid-induced hepatitis. However, recent studies have shown that monitoring for hepatotoxicity can significantly reduce the risk for isoniazid-related death. OBJECTIVE: To evaluate the effectiveness and cost-effectiveness of monitored isoniazid prophylaxis for low-risk tuberculin reactors older than 35 years of age. DESIGN: A Markov model was used to compare the health and economic outcomes of prescribing or withholding a course of prophylaxis for low-risk reactors 35, 50, or 70 years of age. Subsequent analyses evaluated costs and benefits when the effect of transmission of Mycobacterium tuberculosis to contacts was included. MEASUREMENTS: Probability of survival at 1 year, number needed to treat, life expectancy, and cost per year of life gained for individual persons and total population. RESULTS: Isoniazid prophylaxis increased the probability of survival at 1 year and for all subsequent years. For 35-year old, 50-year-old, and 70-year-old tuberculin reactors, life expectancy increased by 4.9 days, 4.7 days, and 3.1 days, respectively, and costs per person decreased by $101, $69, and $11, respectively. When the effect of secondary transmission to contacts was included, the gains in life expectancy per person receiving prophylaxis were 10.0 days for 35-year-old reactors, 9.0 days for 50-year-old reactors, and 6.0 days for 70-year-old reactors. Costs per person for these cohorts decreased by $259, $203, and $100, respectively. The magnitude of the benefit of isoniazid prophylaxis is moderately sensitive to the effect of isoniazid on quality of life. The hypothetical provision of isoniazid prophylaxis for all low-risk reactors older than 35 years of age in the U.S. population could prevent 35,176 deaths and save $2.11 billion. CONCLUSIONS: Monitored isoniazid prophylaxis reduces mortality rates and health care costs for low-risk tuberculin reactors older than 35 years of age, although reductions for individual patients are small. For the U.S. population, however, the potential health benefits and economic savings resulting from wider use of monitored isoniazid prophylaxis are substantial. We should consider expanding current recommendations to include prophylaxis for tuberculin reactors of all ages with no contraindications.

Adult↗

PubMed1997

Cost-effectiveness of implantable cardioverter defibrillators relative to amiodarone for prevention of sudden cardiac death.

BACKGROUND: Implantable cardioverter defibrillators (ICDs) are remarkably effective in terminating ventricular arrhythmias, but they are expensive and the extent to which they extend life is unknown. The marginal cost-effectiveness of ICDs relative to amiodarone has not been clearly established. OBJECTIVE: To compare the cost-effectiveness of a third-generation implantable ICD with that of empirical amiodarone treatment for preventing sudden cardiac death in patients at high or intermediate risk. DESIGN: A Markov model was used to evaluate health and economic outcomes of patients who received an ICD, amiodarone, or a sequential regimen that reserved ICD for patients who had an arrhythmia during amiodarone treatment. MEASUREMENTS: Life-years gained, quality-adjusted life-years gained, costs, and marginal cost-effectiveness. RESULTS: For the base-case analysis, it was assumed that treatment with an ICD would reduce the total mortality rate by 20% to 40% at 1 year compared with amiodarone and that the ICD generator would be replaced every 4 years. In high-risk patients, if an ICD reduces total mortality by 20%, patients who receive an ICD live for 4.18 quality-adjusted life-years and have a lifetime expenditure of $88,400. Patients receiving amiodarone live for 3.68 quality-adjusted life-years and have a lifetime expenditure of $51,000. Marginal cost-effectiveness of an ICD relative to amiodarone is $74,400 per quality-adjusted life-year saved. If an ICD reduces mortality by 40%, the cost-effectiveness of ICD use is $37,300 per quality-adjusted life-year saved. Both choice of therapy (an ICD or amiodarone) and the cost-effectiveness ratio are sensitive to assumptions about quality of life. CONCLUSIONS: Use of an ICD will cost more than $50,000 per quality-adjusted life-year gained unless it reduces all-cause mortality by 30% or more relative to amiodarone. Current evidence does not definitively support or exclude a benefit of this magnitude, but ongoing randomized trials have sufficient statistical power to do so.

Amiodarone↗

PubMed1996

Presentation and explanation of medical decision models using the World Wide Web.

We demonstrated the use of the World Wide Web for the presentation and explanation of a medical decision model. We put on the web a treatment model developed as part of the Cardiac Arrhythmia and Risk of Death Patient Outcomes Research Team (CARD PORT). To demonstrate the advantages of our web-based presentation, we critiqued both the conventional paper-based and the web-based formats of this decision-model presentation with reference to an accepted published guide to understanding clinical decision models. A web-based presentation provides a useful supplement to paper-based publications by allowing authors to present their model in greater detail, to link model inputs to the primary evidence, and to disseminate the model to peer investigators for critique and collaborative modeling.

Arrhythmias, Cardiac↗

PubMed1995

Prevention of sudden cardiac death: a probabilistic model for decision support.

As part of the Cardiac Arrhythmia and Risk of Death Patient Outcomes Research Team (CARD PORT) study we are developing a comprehensive decision model to help physicians identify preferred strategies for preventing sudden cardiac death. The model integrates three components: a screening model, a treatment model, and a value model. Ultimately this model will use the CARD PORT's collective findings to produce policy recommendations and will support patient-specific clinical decision making. Our initial modeling suggests the importance of patient-specific value models in an analysis of treatment options. Although our model is specific to cardiac sudden death, other medical domains that exhibit similar characteristics--the importance of patient preferences and the uncertainty regarding the benefits of strategies for risk stratification and treatment--can use a conceptual framework similar to the approach we used to represent strategies to prevent sudden cardiac death.

Death, Sudden, Cardiac↗

PubMed1994

A computer-based interview to identify HIV risk behaviors and to assess patient preferences for HIV-related health states.

We developed a computer-based utility assessment tool to assess the preferences of patients towards HIV-related health states and identify risk behaviors (both sexual and drug related) of the patient being interviewed. The reliability of the computer-based interview was assessed through comparison with person-to-person interviews. Our pilot study included 22 patients. Twelve of these patients were also interviewed by the research assistants in person-to-person interviews. The agreement between the person-to-person and computer-based interviews was excellent (3 discrepancies of 180 compared answers), and the majority of the patients preferred to use the computer to disclose sensitive information regarding risk behaviors. Our study suggests that assessment of patient preferences and risk factors can be performed reliably through a computer-based interview.

Adult↗

PubMed1993

Computed tomography for nontraumatic headache: current utilization and cost-effectiveness.

A retrospective study was performed at two teaching hospitals--one in the United States and one in Canada--to determine the results of computed tomography (CT) examinations of the head in patients with nontraumatic headache. Of 1111 examinations performed over a 3-year period, 120 (10.8%) demonstrated an acute intracranial abnormality, such as hemorrhage, infarction or tumour; the frequency of such abnormalities was highest among inpatients and subjects over 40 years of age. Cranial and extracranial abnormalities, such as sinusitis and metastases to the calvarium, were found in 40 (3.6%) of the cases. Chronic abnormalities, such as cerebral atrophy or remote infarction, were the most significant findings in 202 (18.2%) of the cases. The cost of finding each case of acute intracranial abnormality was $5962 (US); for subarachnoid hemorrhage among patients in the emergency department, it was $15,837 (US).

Adolescent↗

PubMed1991

The potential use of expert systems to enable physicians to order more cost-effective diagnostic imaging examinations.

Educating physicians to order diagnostic imaging examinations more cost-effectively is a difficult and time consuming task, which may be assisted significantly by the use of an expert system. This report is based on a study undertaken at the Health Sciences Centre in Winnipeg, Manitoba, to determine the feasibility of implementing an expert system to aid physicians in selecting appropriate imaging studies. The report reviews the potential benefits, requirements, and limitations of expert systems under development, and highlights the major issues to be considered in choosing such a system for implementation. An extensive literature search was done and is included to aid the reader interested in pursuing this opportunity for improving the cost-effective utilization of expensive diagnostic imaging resources.

Computer-Assisted Instruction↗

PubMed1974