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Echocardiographic Identification of Cardiovascular Sources of Emboli To Guide Clinical Management of Stroke: A Cost-Effectiveness Analysis

Robert L. McNamara, MD, MHS; Joao A.C. Lima, MD; Paul K. Whelton, MD, MSc; and Neil R. Powe, MD, MPH, MBA
[+] Article and Author Information

For author affiliations and current author addresses, see end of text. For definitions of terms used, see Glossary at end of text. Grant Support: In part by training grant T32 HL07024-21 from the National Heart, Lung, and Blood Institute, Bethesda, Maryland (Dr. McNamara); grant KO1 AG00561 from the National Institute on Aging, Bethesda, Maryland (Dr. Powe); and General Clinical Research Grant 5M01RR00722 from the National Center for Research Resources, National Institutes of Health. Requests for Reprints: Neil R. Powe, MD, MPH, MBA, Welch Center for Prevention, Epidemiology, and Clinical Research, The Johns Hopkins Medical Institutions, 2024 East Monument Street, Suite 2-645, Baltimore, MD 21250-2223. Current Author Addresses: Dr. McNamara, MD, MHS, School of Hygiene and Public Health, Room 6009, 615 North Wolfe Street, Baltimore, MD 21117.


Copyright ©2004 by the American College of Physicians


Ann Intern Med. 1997;127(9):775-787. doi:10.7326/0003-4819-127-9-199711010-00001
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Background: No consensus exists about the use of imaging strategies to identify potential cardiovascular sources of emboli in patients who have had strokes.

Objective: To determine the cost-effectiveness of various cardiac imaging strategies after stroke.

Design: A Markov model decision analysis was used to evaluate the benefits and costs of nine diagnostic strategies, including transthoracic echocardiography, transesophageal echocardiography, sequential approaches, selective imaging, and no imaging.

Setting: Simulated clinical practice in the United States.

Patients: Hypothetical patients with a first stroke who were in normal sinus rhythm.

Measurements: Echocardiographic detection rates of potential sources of emboli were ascertained by doing a systematic review of the literature. Values for event rates, anticoagulation effects, utilities, and costs were obtained from the literature and Medicare data.

Results: When visualized left atrial thrombus was used as the only indication for anticoagulation, transesophageal echocardiography performed only in patients with a history of cardiac problems cost $9000 per quality-adjusted life-year; transesophageal echocardiography in all patients cost $13 000 per quality-adjusted life-year. Cost savings and decreased morbidity and mortality rates associated with reduction in preventable recurrent strokes substantially offset examination costs and risks of anticoagulation. These results were moderately sensitive to efficacy of anticoagulation and incidence of intracranial bleeding during anticoagulation and were mildly sensitive to prevalence of left atrial thrombus, rate of recurrent stroke in patients with thrombus, quality of life after stroke, cost of transesophageal echocardiography, and specificity of transesophageal echocardiography. Transthoracic echocardiography, alone or in sequence with transesophageal echocardiography, was not cost-effective compared with transesophageal echocardiography.

Conclusion: Physicians should consider doing transesophageal echocardiography in all patients with new-onset stroke.

Figures

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Figure 1.
Nine possible diagnostic strategies for patients with stroke.

The square labeled “Stroke” at left indicates the starting point in the decision process. The nine strategies used combinations of cardiac history, transthoracic echocardiography (TTE), and transesophageal echocardiography (TEE). Positive (+) and negative − signs indicate the results of cardiac history or imaging. No label after a test indicates that no further testing was done.

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Figure 2.
Health states for the Markov model.Figure 1

Patients began with one of four underlying pathologic conditions, shown at left. Patients received anticoagulants on the basis of whether potential sources of emboli were identified by using the diagnostic strategies in . Each group of patients was then followed through monthly cycles for recurrent cerebrovascular accident (CVA), intracranial hemorrhage (ICH), gastrointestinal bleeding (GIB), or death. Utilities and costs for each health state accumulated over time.

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Figure 3.
Cost-effectiveness of diagnostic strategies compared with the treat-none strategy.

See Glossary for descriptions of strategies. Absolute cost and effectiveness of the treat-none strategy as specified in the model were $4740 and 4.854 quality-adjusted life-years (QALYs) per patient, respectively. Incremental costs and effectiveness compared with those of the treat-none strategy are also shown.

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Figure 4.
Cost-effectiveness over different time horizons.

The cost-effectiveness of the all-transesophageal and selective-transesophageal strategies compared with the treat-none strategy in separate analyses that have different lengths of patient follow-up is shown. QALY = quality-adjusted life-year.

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Figure 5.
One-way sensitivity analysis.

Ranges of cost-effectiveness of the all-transesophageal strategy compared with the treat-none strategy are shown. Ranges of input variables are shown next to each bar. Less than $20 000 per quality-adjusted life-year (QALY) was a favorable cost-effectiveness ratio; more than $100 000 per quality-adjusted life-year represents an unfavorable ratio. No strong conclusions were drawn about values between $20 000 and $100 000 per quality-adjusted life-year. Values less than zero indicate cost savings for the all-transesophageal strategy.

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Figure 6.
Trade-off in anticoagulation efficacy and safety in two-way sensitivity analysis.

Diagonal lines represent the rate of intracranial hemorrhage at which a given rate of stroke reduction is no longer cost-effective for the all-transesophageal strategy compared with the treat-none strategy. The cost-effectiveness ratios of $20 000 per quality-adjusted life-year (QALY) and $100 000 per quality-adjusted life-year were used as the transition points from a favorable to an indeterminate to an unfavorable ratio.

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