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David B Matchar

Publications and source records attributed to David B Matchar.

46 records · Page 3Linked to original sources
PubMed2002

Which approach to anticoagulation management is best? Illustration of an interactive mathematical model to support informed decision making.

BACKGROUND: Among patients with atrial fibrillation or mechanical heart valves, determining the best approach to oral anticoagulation largely depends on comparing the costs of anticoagulation management with the costs of events (thromboembolism and bleeding) averted. The Anticoagulation Management Event/Cost Model (ACME) is an interactive mathematical model intended to help clarify these trade-offs. METHODS: The ACME is a series of linked, nested spreadsheets. At the least detailed level, the user specifies the percentage of patients falling into various management strategies (no anticoagulation, usual physician care, anticoagulation service, patient self-testing/self-management), and the ACME estimates event rates and costs. At more detailed levels the ACME performs a series of weighted average calculations combining, for example, utilization times unit price. Cost categories are divided into event-related and management-related costs (costs of management, testing, and medication). RESULTS: Regardless of how anticoagulation is subsequently managed, perhaps the greatest benefit is obtained by moving patients who are not currently receiving anticoagulation onto warfarin. Additional benefits can be obtained by eliminating outliers (extremely high or extremely low anticoagulation levels). If changing to a more intensive approach also serves to reduce the tendency for physicians to prescribe anticoagulate below the optimal range, additional savings can be anticipated. The cost calculation typically involves a trade-off between increased up-front costs of anticoagulation management versus greater down-line savings associated with a decreased number of events. To assess the quality of anticoagulation within a given organization, it is critical to know the distribution of clotting levels for the population under anticoagulation. CONCLUSIONS: Interactive mathematical models, if sufficiently well documented, can be helpful in clarifying decisions regarding costs and benefits of various methods of anticoagulation.

Anticoagulants↗
PubMed2002

Cost-effectiveness of ancrod treatment of acute ischaemic stroke: results from the Stroke Treatment with Ancrod Trial (STAT).

RATIONALE, AIMS AND OBJECTIVES: This paper describes a recent randomized controlled trial in which 42% of patients receiving ancrod attained a favourable outcome in comparison with 34% of controls. Although the above effect size corresponds to a number needed to treat (to achieve a favourable outcome) of approximately 13, intuition does not necessarily suggest what would be the overall impact of a treatment with this level of efficacy. METHODS: The objective was to evaluate the cost-effectiveness of ancrod. Cost-effectiveness analysis of data from the Stroke Treatment with Ancrod Trial (STAT) trial was carried out. The participants were 495 patients with data on functional status at the conclusion of follow-up. Short-term results were based upon utilization and quality of life observed during the trial; these were merged with expected long-term results obtained through simulation using the Stroke Policy Model. The main outcome measure was incremental cost-effectiveness ratio. RESULTS: Ancrod treatment resulted in both better quality-adjusted life expectancy and lower medical costs than placebo as supported by sensitivity analysis. The cost differential was primarily attributable to the long-term implications of ancrod's role in reducing disability. CONCLUSIONS: If ancrod is even modestly effective, it will probably be cost-effective (and, indeed, cost-saving) as well. The net population-level impact of even modestly effective stroke treatments can be substantial.

Adult↗
PubMed2002

To what extent should quality of care decisions be based on health outcomes data? Application to carotid endarterectomy.

BACKGROUND AND PURPOSE: Most quality improvement methods implicitly assume that facilities with high complication rates are likely to have substandard processes of care, a stable characteristic that, in the absence of intervention, will persist over time. We assessed the extent to which this holds true for carotid endarterectomy. METHODS: Using data from the Department of Veterans Affairs National Surgical Quality Improvement Project, we classified facilities on the basis of 30-day complications of carotid endarterectomy (stroke, myocardial infarction, death) during 1994 to 1995 (period 1, n=3389) and then compared these groups of facilities for complication rates during 1996 to 1997 (period 2, n=4453). RESULTS: Despite wide variation in facility-specific complication rates, the correlation between rates in periods 1 and 2 was low (Spearman correlation coefficient, 0.04; P=0.01) Facility-specific rates did not show greater correlation when we examined only facilities with higher volumes patients in different clinical categories (asymptomatic, transient ischemic attack, stroke). Comorbid illness profiles were similar between the 2 time periods. CONCLUSIONS: Most of the facility-specific differences in complication rates in period 1 were not maintained into period 2. Many apparent quality improvement problems may not be as large as they first appear, especially when based on few complications per facility. The inability, in practice, to estimate complication rates at a high degree of precision is a fundamental difficulty for clinical policy making regarding procedures with complication rates such as carotid endarterectomy.

Aged↗
PubMed2002

Disease management in healthcare organizations: results of in-depth interviews with disease management decision makers.

BACKGROUND: Despite the widening use of disease management (DM) programs throughout the country, little is understood about the "state of DM" in healthcare systems and managed care organizations. OBJECTIVE: To better characterize the range of users of DM in healthcare and to identify critical issues, both present and future, for DM. STUDY DESIGN: Qualitative survey. PARTICIPANTS AND METHODS: Forty-seven healthcare systems (n = 22) and managed care organizations (n = 25) were randomly selected. Decision makers were identified and interviewed between January 1, 2000, and March 31, 2000. We limited quantitative analysis to tabulations of suitable responses, without statistical testing. Responses were organized around 3 themes: models for DM, implementation strategies, and measurements of success. RESULTS: Of 47 decision makers surveyed, 42 (89%) reported that their organizations currently have (75%) or are working to develop (14%) DM programs. Although the goals of DM programs were similar, organizations took a variety of approaches to achieving these ends. There were typically 3 steps in implementing a DM program: analysis of patient data, external analysis, and organizational analysis. Decision makers believed that DM programs had only achieved partial success in reaching the 2 main goals of improved quality of care and cost savings. CONCLUSIONS: Given the variety of DM programs, there is a need to develop a classification scheme to allow for better comparison between programs. Further quantitative studies of decision makers' opinions would be helpful in developing programs and in designing necessary studies of patient management strategies.

Decision Making, Organizational↗
PubMedDate not supplied

When should functional neuroimaging techniques be used in the diagnosis and management of Alzheimer's dementia? A decision analysis.

BACKGROUND: Functional neuroimaging, including positron emission tomography (PET), has been proposed for use in diagnosing Alzheimer's disease-related dementia (AD). OBJECTIVE: The objective of this study was identify the circumstances under which PET scanning for the diagnosis of AD maximizes health outcomes. METHODS: A Markov-model-based decision analysis was conducted using estimates derived from the literature on AD epidemiology, the accuracy of PET, and donepezil treatment efficacy. The target population for the analysis was assumed to be US men and women who either have mild AD or are asymptomatic but at an elevated risk of developing AD owing to disease in a first-degree relative (parent or sibling). The time horizon was the patient lifetime. We compared treatment 1) based on an American Academy of Neurology (AAN) clinical evaluation either alone; 2) in combination with PET scanning; or 3) empirically based on a family history. Outcomes measures were life expectancy, quality-adjusted life-years (QALYs), and (severe) dementia-free life expectancy (SDFLE). RESULTS: For both patient populations, treating all patients based on an AAN evaluation without further testing using PET resulted in the greatest gains in life expectancy, QALYs, and SDFLEs. PET-based testing was the second preferred strategy compared to no intervention. The rankings of the strategies were sensitive to severity of treatment complications: analyses of hypothetical treatments with the potential for severe complications indicated that testing was preferred if the treatment was effective but had moderate complications. CONCLUSIONS: These results suggest that current treatments, which are relatively benign and may slow progression of disease, should be offered to patients who are identified as having AD based solely on an AAN clinical evaluation. A clinical evaluation that includes functional neuroimaging based testing will be warranted, however, when new treatments that are effective at slowing disease progression but have the potential for moderate to severe complications become available.

Aged↗
PubMedDate not supplied

Headache management program improves outcome for chronic headache.

OBJECTIVE: To determine the feasibility of developing a headache management program and to assess the outcomes of patients referred to the program for treatment of chronic headache. BACKGROUND: Effective headache treatment requires that the patient receives the correct headache diagnosis; that appropriate acute and, if indicated, preventive medications be prescribed; and that the patient receives adequate education, including headache self-management skills. DESIGN/METHODS: A headache management program was established at a northern California staff-model health maintenance organization. Fifty-four patients were enrolled in the program and followed for 6 months. Patients participated in a structured program of group and individual sessions with the program manager. Data collection at baseline and 6 months included the Migraine Disability Assessment (MIDAS), the Short Form-36 Health Survey (SF-36), a patient satisfaction survey, and 2 additional short surveys--one that assessed patient worries about their headaches and another that queried patients on their problems with headache management. RESULTS: All enrolled patients participated in the initial group visit; 74% had at least one additional visit. All but one patient suffered from more than one headache type. Sixty-one percent of patients suffered from migraine headache and 98% from tension-type headache. At baseline, patients were severely disabled, with a mean MIDAS score of 41. At 6 months, MIDAS scores decreased an average of 21.2 points (P <.005). Patients reported 14.5 fewer days with headache over the preceding 3 months (P <.0001) and experienced clinically significant improvements in 6 of the SF-36 subscales. Patients were significantly more satisfied with their headache care (P <.0001), reported less problems with their headache management (P <.0001), and were less worried about their headaches (P <.01). During the intervention, emergency department visits for headache decreased (P <.02). CONCLUSIONS: A headache management program was successfully established. Patients referred to the program experienced significant improvement in headache-related disability and functional health status and reported greater satisfaction with care. Even so, these results were obtained at one site and in a small sample that was not randomized. We currently are conducting a randomized controlled trial to better evaluate the clinical and financial impact of a headache management program for patients with chronic headache.

Adult↗
PubMedDate not supplied

Cost-effectiveness of antiplatelet agents in secondary stroke prevention: the limits of certainty.

UNLABELLED: Which of the available antiplatelet therapies should be preferred for secondary prevention of recurrent ischemic stroke has been contentious. OBJECTIVE: We applied the Duke Stroke Policy Model (DSPM) to reconsider this issue, paying particular attention to the degree of uncertainty in the estimates of their efficacy. The DSPM is a continuous-time simulation model of stroke development and outcome. METHODS: We modified the inputs to reflect the cost of the drugs aspirin (ASA), extended release dipyridamole/aspirin (DP/A) and clopidogrel (CLO), as well as their relative risk in preventing subsequent ischemic stroke in comparison with placebo (PBO). These relative risks were derived from published reports from the second European Stroke Prevention Study (ESPS-2) and Clopidogrel Versus Aspiring in Patients at Risk of Ischemic Events studies. Precision was addressed by applying bootstrapping to the above estimates of relative risk. The target population was 70-year-old men with nondisabling stroke. The outcome measures were quality-adjusted life-years (QALYs), costs, and costs per QALY. RESULTS: Results of Base Case Analysis: In large part because of its modest drug cost, ASA was cost-effective in comparison with PBO. DP/A tended to have improved outcomes, but at increased costs. CLO was dominated in the base case. RESULTS OF SENSITIVITY ANALYSIS: ASA and DP/A cannot be differentiated on a statistical basis alone. In probabilistic sensitivity analysis, CLO was rarely preferred. CONCLUSIONS: Either DP/A or ASA appear to be a good value in comparison with no treatment, but there is no clear winner between the two. In the absence of a definitive randomized trial, simulation modeling can help clarify the trade-offs between the various antiplatelet agents, but not beyond the constraints imposed by the imprecision in the estimates that can be obtained from the current evidence base.

Aged↗
PubMedDate not supplied

When to stress over triptans: a Markov analysis of cardiovascular risk in migraine treatment.

BACKGROUND: Migraines affect 10% of the U.S. population and the episodes are frequently associated with significant disability. Triptans, 5HT1 receptor agonists, can be highly effective in treating pain and reducing disability. However, reports of cardiac events associated with triptan ingestion have led to concerns about its use in the face of possible cardiac disease. OBJECTIVE: Should a patient without known cardiovascular disease (CAD) and moderately severe to severe migraines undergo cardiovascular testing prior to the initiation of triptan therapy? DESIGN: A Markov model of migraine and cardiac disease using DATA 4.0. Three strategies were compared: (1) use triptans without further evaluation (TREAT); (2) test, then treat if negative (TEST); and (3) avoid triptans (NOTRIPTAN). Triptans were prohibited if a cardiac event occurred. DATA: Model inputs were derived from the literature and subjected to sensitivity analyses across all possible values. TIME HORIZON: Markov cycle is 1 week. OUTCOMES: The primary outcomes of interest were quality-adjusted life expectancy, in years (QALYs) and the impact of various cardiovascular risk levels on the preferred strategy. RESULTS: For the base case results were TREAT 19.4 QALYs, TEST 19.2, NOTRIPTAN 19.1. When altering CAD probability: TREAT dominated from 0 to 87%, TEST 87% to 97%, and NOTRIPTAN above 97%. Results were robust during sensitivity analyses. CONCLUSIONS: This analysis suggests that even for individuals with a relatively high risk of CAD it is not beneficial to perform cardiac testing, nor to avoid triptans. The exact level of cardiac risk at which testing should be considered is probably at or above 87%.

Cardiovascular Diseases↗
PubMedDate not supplied

Use of data from nonrandomized trial designs in evidence reports: an application to treatment of pulmonary disease following spinal cord injury.

Evidence reports summarize the evidence pertaining to various health-related topics. Including evidence from nonrandomized studies into such reports involves a trade-off between availability and bias. We describe a general framework by which information from nonrandomized studies might be integrated reasonably into evidence reports and illustrate its application to a recent evidence report on preventing pulmonary complications among patients with spinal cord injury. The proposed framework, which is based upon the premise that producing a fair summary of the evidence requires only a level of evidence judged by clinical experts to be sufficient to the task at hand, may help focus scarce resources, strengthen the quality and documentation of decisions including evidence from nonrandomized studies, and suggest high-priority areas for future research.

Evidence-Based Medicine↗