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To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.annemergmed.2006.09.019 Byline: E. Brooke Lerner (a)(f), Graham Nichol (b), Daniel W. Spaite (c), Herbert G. Garrison (d), Ronald F. Maio (e) Abstract: To determine the cost of an emergency medical services (EMS) system, researchers, policymakers, and EMS providers need a framework with which to identify the components of the system that must be included in any cost calculations. Such a framework will allow for cost comparisons across studies, communities, and interventions. The objective of this article is to present an EMS cost framework. This framework was developed by a consensus panel after analysis of existing peer-reviewed and non-peer-reviewed resources, as well as independent expert input. The components of the framework include administrative overhead, bystander response, communications, equipment, human resources, information systems, medical oversight, physical plant, training, and vehicles. There is no hierarchical rank to these components; they are all necessary. Within each component, there are subcomponents that must be considered. This framework can be used to standardize the calculation of EMS system costs to a community. Standardizing the calculation of EMS cost will allow for comparisons of costs between studies, communities, and interventions. Author Affiliation: (a) Department of Emergency Medicine and Department of Community and Preventive Medicine, University of Rochester, Rochester, NY (Lerner) (b) University of Washington-Harborview Center for Prehospital Emergency Care and Emergency Services, Harborview Medical Center, University of Washington, Seattle, WA (Nichol) (c) Arizona Emergency Medicine Research Center, Department of Emergency Medicine, College of Medicine, University of Arizona, Tucson, AZ (Spaite) (d) Department of Emergency Medicine, East Carolina University, Greenville, NC (Garrison) (e) Department of Emergency Medicine, University of Michigan, Ann Arbor, MI (Maio) (f) Department of Emergency Medicine at the Medical College of Wisconsin, Milwaukee, WI Article History: Received 31 May 2006; Revised 21 September 2006; Accepted 22 September 2006 Article Note: (footnote) Supervising editor: Donald M. Yealy, MD, Funding and support: This work was funded by the National Highway Traffic Safety Administration through Cooperative Agreement DTNH22-98-H-05117 awarded to the National Association of State EMS Directors., Reprints not available from the authors.

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.annemergmed.2006.01.012 Byline: E. Brooke Lerner (a), Ronald F. Maio (b), Herbert G. Garrison (c), Daniel W. Spaite (d), Graham Nichol (e) Abstract: The evaluation of the impact of out-of-hospital emergency care is a relatively new research focus. As such, there is a compelling need to determine how finite health care resources should be used in this setting. The objective of this study is to conduct a structured review of published economic evaluations of out-of-hospital emergency care to assess its economic value. Author Affiliation: (a) Department of Emergency Medicine and Department of Community and Preventive Medicine, University of Rochester, Rochester, NY (b) Department of Emergency Medicine, University of Michigan, Ann Arbor, MI (c) Department of Emergency Medicine, East Carolina University, Greenville, NC (d) Department of Emergency Medicine, College of Medicine, University of Arizona, Tucson, AZ (e) University of Washington-Harborview Center for Prehospital Emergency Care and Emergency Services, Harborview Medical Center, University of Washington, Seattle, WA. Article History: Received 9 November 2005; Revised 5 January 2006; Accepted 6 January 2006 Article Note: (footnote) Supervising editor: Donald M. Yealy, MD, Funding and support: This work was funded by the National Highway Traffic Safety Administration through Cooperative Agreement DTNH22-98-H-05117 awarded to the National Association of State EMS Directors. The sponsor played no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; or preparation, review, or approval of the manuscript., Reprints not available from the authors.

Background: Atrial fibrillation is the most common type of sustained cardiac arrhythmia, but recent trials have identified no clear advantage of rhythm control ever rate control. Consequently, economic factors often play a role in guiding treatment selection. Objective: To estimate the cost-effectiveness of rhythm-control versus rate-control strategies for atrial fibrillation in the Atrial Fibrillation Follow-up Investigation of Rhythm Management (AFFIRM). Design: Retrospective economic evaluation. Nonparametric boot-strapping was used to estimate the distribution of incremental costs and effects on the cost-effectiveness plane. Data Sources: Data on survival and use of health care resources ware obtained for all 4060 AFFIRM participants. Unit costs were estimated from various U.S. databases. Target Population: patients with atrial fibrillation who were 65 years of age or who had other risk factors for stroke or death, similar to those enrolled in AFFIRM. Time Horizon: Mean follow-up of 3.5 years. Perspective: Third-party payer. Interventions: Management of patients with atrial fibrillation with antiarrhythmic drugs (rhythm control) compared with drugs that control heart rate (rate control). Outcome Measures: Mean survival, resource use, costs, and cost-effectiveness. Results of Base-Case Analysis: A mean survival gain of 0.08 year (P = 0.10) was observed for rate control. Patients in the rate-control group used fewer resources (hospital days, pacemaker procedures, cardioversions, and short-stay and emergency department visits). Rate control costs $5077 less per person than rhythm control. Results of Sensitivity Analysis: Cost savings ranged from $2189 to $5481 per person. Rhythm control was mere costly and less effective than rate control in 95% of the bootstrap replicates over a wide range of cost assumptions. Limitations: Resource use was limited to key items collected in AFFIRM, and the results are generalizable only to similar patient populations with atrial fibrillation. Conclusion: Rate control is a cost-effective approach to the management of atrial fibrillation compared with maintenance of sinus rhythm in patients with atrial fibrillation similar to thOse enrolled in AFFIRM.

Abstract Background: Survivors of out-of-hospital cardiac arrest are at high risk of recurrent arrests, many of which could be prevented with implantable cardioverter defibrillators (ICDs). We sought to determine the [...]

Background: Heart failure is a common, costly, and debilitating illness. Resynchronization of ventricular contraction in patients with heart failure improves ejection fraction. The long-term morbidity and costs associated with such cardiac resynchronization therapy remain unclear. Objective: To assess the incremental cost-effectiveness of cardiac resynchronization therapy. Design: Markov model with Monte Carlo simulation. Future costs and effects were discounted at 3%. Data Sources: Effects data were obtained from a concurrent systematic review. Health-related quality-of-life and cost data were obtained from publicly available data or from surveys. Target Population: Patients with reduced ventricular function and prolonged QRS. Time Horizon: Lifetime. Perspective: U.S. health care system. Interventions: Cardiac resynchronization therapy versus medical therapy. Outcome Measures: Quality-adjusted life-years (QALYs), costs, and incremental cost-effectiveness. Results of Base-Case Analysis: Medical therapy yielded a median of 2.64 (interquartile range, 2.47 to 2.82) discounted QALYs and a median discounted lifetime cost of $34 400 (interquartile range, $31 100 to $37 700). Cardiac resynchronization therapy was associated with a median incremental cost of $107 800 (interquartile range, $79 800 to $156 500) per additional QALY. Results of Sensitivity Analysis: Results were sensitive to changes in several variables, including the relative risk for death or hospitalization. Limitations: These results apply to patients who meet the inclusion criteria of the currently completed trials. Conclusions: The incremental cost per QALY for cardiac resynchronization is similar to that of other commonly used interventions but is sensitive to changes in several key variables. Resynchronization therapy should not be considered in patients with comorbid illness that shortens life expectancy.

Byline: Graham Nichol, Ian G Stiel, George A Wells, Lars S Juergensen, Andreas Laupacis Abstract: Study objective: To conduct an economic analysis of the implementation of the Ottawa Knee Rule. Methods: The decision analysis compared usual practice based on physician judgment with practice based on a clinical decision rule, which allows more selective use of radiography. The study participants were all adults with blunt knee trauma. The likelihood and cost of radiography, missed fracture, lost productivity, and medicolegal actions were defined by published data and an expert panel. Separate analyses considered US Medicare and Canadian hospital costs. Sensitivity analyses considered a range of values for each variable in the model, including costs in a US fee-for-service setting. The study out-come was the mean cost per patient. Results: The mean cost savings associated with practice based on the Ottawa Knee Rule was $31 (95% confidence interval 22 to 44) to $34 (95% confidence interval 24 to 47) per patient. These results were robust to reasonable changes in the values of variables in the model. Conclusion: Implementation of the Ottawa Knee Rule Would be associated with meaningful reductions in societal health care costs both in the United States and Canada without a reduction in quality of care. Author Affiliation: Clincal Epidemiology Unit, Loeb Health Research Institute, University of Ottawa, Ottawa, Ontario, Canada Article History: Received 2 October 1997; Revised 22 July 1998; Accepted 17 May 1999 Article Note: (footnote) * Presented in part at the Society for Academic Emergency Medicine annual meeting, Washington, DC, April 1997, and the International Society for Technology Assessment in Health Care Annual Meeting, Barcelona, Spain, May 1997, ** Supported in part by a grant (11095N) from the Emergency Health Services Branch of the Ontario Ministry of Health. Drs Stiell and Laupacis hold Scientist Awards from the Medical Research Council of Canada. Dr Nichol is a Career Scientst of the Ontario Ministry of Health.

Byline: Graham Nichol (*)(a ), Ian G Stiell (*)(As.), Andreas Laupacis (*)(a ), Ba' Pham (a[yen]), Valerie J De Maio (*), George A Wells (*) Abstract: Study objective: More than 1,000 patients experience sudden cardiac arrest each day. Treatment for this includes cardiopulmonary resuscitation (CPR_ and emergency medical services (EMS) that provide CPR-basic life support (BLS), BLS with defibrillation (BLS-D), or advanced life support (ALS). Our previous systematic review of treatments for sudden cardiac arrest was limited by suboptimal data. Since then, debate has increased about whether bystander CPR is effective or whether attention should focus instead on rapid defibrillation. Therefore a cumulative meta-analysis was conducted to determine the relative effectiveness of differences in the defibrillation response time interval, proportion of bystander CPR, and type of EMS system on survival after out-of-hospital cardiac arrest. Methods: A comprehensive literature search was performed by using a priori exclusion criteria. We considered EMS systems that provided BLS-D, ALS, BLS plus ALS, or BLS-D plus ALS care. A generalized linear model was used with dispersion estimation for random effects. Results: Thirty-seven eligible articles described 39 EMS systems and included 33, 124 patients. Median survival for all rhythm groups to hospital discharge was 6.4% (interquartile range, 3.7 to 10.3). Odds of survival were 1.06 (95% confidence interval [Cl], 1.03 to 1.09; P Conclusion: We confirm that greater survival after sudden cardiac arrest is associated with provision of bystander CPR, early defibrillation, or ALS. More research is required to evaluate the relative benefit of early defibrillation versus early ALS. Author Affiliation: (*) Clinical Epidemiology Unit, Loeb Health Research Institute, Ottawa, Ontario, Canada (a ) Division of General Hospital, Ottawa, Ontario, Canada (As.) Division of Medicine, University of Ottawa, Ottawa Ontario, Canada (a[yen]) Children's Hospital of Eastern Ontario Research Institute, Ottawa, Ontario, Canada Article Note: (footnote) * Presented in part at the annual meeting of Society or Academic Emergency Medicine, Chicago, IL, May 1998., * Supported in part by the Emergency Health Services of the Ontario Ministry of Health (#12096S). Dr Nichol is supported by an Ontario Ministry of Health Career Scientist Award. Drs Laupacis and Stiell are supported by Career Scientist Awards from the Medical Research Council of Canada

Purpose: To examine the cost-effectiveness of test-treatment strategies for patients suspected of having Lyme disease. Data Sources: The medical literature was searched for information on outcomes and costs. Expert opinion was sought for information on utilities. Study Selection: Articles that described patient population, diagnostic criteria, dose and duration of therapy, and criteria for assessment of outcomes. Data Extraction: The decision analysis evaluated the following strategies: 1) no testing-no treatment; 2) testing with enzyme-linked immunosorbent assay (ELISA) followed by antibiotic treatment of patients with positive results; 3) two-step testing with ELISA followed by Western blot and antibiotic treatment for patients with positive results on either test; and 4) empirical antibiotic therapy. Three patient scenarios were considered: myalgic symptoms, rash resembling erythema migrans, and recurrent oligoarticular inflammatory arthritis. Results were calculated as costs per quality-adjusted life-year and were subjected to sensitivity analysis. Adjustment was made for the diagnostic value of common clinical features of Lyme disease. Data Synthesis: For myalgic symptoms without other features suggestive of Lyme disease, the no testing-no treatment strategy was most economically attractive (that is, had the most favorable cost-effectiveness ratio). For rash, empirical antibiotic therapy was less costly and more effective than other strategies. For oligoarticular arthritis with a history of rash and tick bite, two-step testing was associated with the lowest cost-effectiveness ratio. Testing with ELISA and empirical antibiotic therapy cost an additional $880 000 and $34 000 per quality-adjusted life-year, respectively. For oligoarticular arthritis with one or no other features suggestive of Lyme disease, two-step testing was most economically attractive. Conclusions: Neither testing nor antibiotic treatment is cost-effective if the pretest probability of Lyme disease is low. Empirical antibiotic therapy is recommended if the pretest probability is high, and two-step testing is recommended if the pretest probability is intermediate., Based on recently published research, cost-effective tactics for testing and treating patients with suspected Lyme disease have been analyzed and presented. Immediate antibiotic therapy appears to be the most cost-effective treatment strategy for patients with physical evidence highly suggestive of Lyme disease. A two-tiered testing approach using the enzyme-linked immunosorbent assay and Western blot assay appears to be the most cost-effective approach for patients with a reasonable likelihood of having Lyme disease. A conservative approach may be most appropriate for patients with a low likelihood of having Lyme disease.

Purpose: To provide a quantitative and qualitative evaluation of the predictive value of the laboratory diagnosis of Lyme disease and to use the resultant data to formulate guidelines for clinical diagnosis. Data Sources: A MEDLINE search of English-language articles or articles with English-language abstracts published from 1982 to 1996. Data Extraction: Sensitivity, specificity, and likelihood ratios were calculated, and a random-effects model was used to combine the proportions from the eligible studies. Prespecified criteria were used to determine which studies were eligible for analysis. Data Synthesis: Laboratory testing in general is not clinically useful if the pretest probability of Lyme disease is less than 0.20 or greater than 0.80. When the pretest probability is 0.20 to 0.80, sequential testing with enzyme-linked immunosorbent assay and Western blot is the most accurate method for ruling in or ruling out the possibility of Lyme disease. Conclusions: Laboratory testing is recommended only in patients whose pretest probability of Lyme disease is 0.20 to 0.80. If the pretest probability is less than 0.20, testing will result in more false-positive results than true-positive results; a negative test result in this situation effectively rules out the disease., Research suggests that blood testing for Lyme disease should be used cautiously. Guidelines for Lyme disease testing were developed based on statistical analyses performed on Lyme disease research studies published between 1982 and 1996. Blood testing appears to be appropriate for patients with a 20% to 80% likelihood of having the disease. False-positive results are high in patients with less than a 20% likelihood of having Lyme disease. A two-tiered testing approach using enzyme-linked immunosorbent assays and Western blot testing appears to most effectively identify patients with true Lyme disease.

Background: Use of resources for patients with acute chest pain may be improved with clinical strategies that integrate research, Bayesian analysis, and expert opinion. Objectives: To 1) develop a critical pathway for management of patients with acute chest pain who are at low risk for complications of ischemic heart disease and 2) assess the potential effects of implementation of the pathway on patient safety and resource use. Design: Evidence-based consensus and prospective cohort study. Setting: Urban teaching hospital. Patients: Patients at least 30 years of age who were seen in the emergency department for chest pain and who did not have a history of trauma or abnormalities on radiologic study. Intervention: Physician-opinion leaders defined criteria for patient inclusion in the pathway and for remaining on the pathway after 6 or 12 hours of observation. Criteria were defined for appropriateness of direct admission, direct discharge, or 6 hours of observation followed by exercise treadmill testing. Measurements: Number of patients admitted to the hospital, number of days that patients were hospitalized, and clinical outcome. Results: 2898 of 4585 patients (63%) were admitted to the hospital; of the 2898, 1152 (40%) were classified as potentially eligible for the pathway and 1068 (93%) had a benign clinical course during the initial observation period. The 1068 patients had a mean length of stay of 2.8 [+ or -] 4.8 days. if 47% of these patients had been discharged after observation and exercise testing, implementation of the pathway would have reduced the number of admissions by 505 (17%) and days of hospitalization by 1407 (11%). Conclusions: Retrospective analysis suggests that a critical pathway for patients with acute chest pain may substantially reduce resource use. Prospective study is needed to ensure increased efficiency without increased adverse outcomes., A strategy for determining appropriate treatment options for patients with chest pain who have a low risk of heart attack may be safe and cost-effective. This strategy, called a critical pathway, was analyzed for 1,152 low-risk patients admitted to the hospital with chest pain. Nearly all of these patients had no further complications during their hospital stay. Careful observation followed by an exercise stress test could have safely reduced the number and length of hospital admissions among these patients.

Byline: Graham Nichol, Andreas Laupacis, Ian G Stiell, Keith O'Rourke, Aslam Anis, Hildo Bolley, Allan S Detsky Abstract: Study objective: To measure the incremental cost-effectiveness of various improvements to emergency medical services (EMS) systems aimed at increasing survival after out-of-hospital cardiac arrest. Methods: We performed cost-effectiveness analysis based on (1) metaanalysis of effectiveness of the various EMS systems, (2) costing of each component of EMS systems, (3) modeling of the relationship between the proportion of cardiac arrest victims who receive CPR and the proportion of individuals trained, (4) modeling of the relationship between response time interval and the characteristics of the EMS system, (5) measurement of quality of life, and (6) decision analysis to combine the results of the first five components. Results: The incremental cost-effectiveness ratio for a 48-second improvement in mean response time in a one-tier EMS system yielded by the addition of more EMS providers was $368,000 per quality-adjusted life year (QALY). For improved response time in a two-tier EMS system by the addition of more basic life support (BLS)/BLS-defibrillator (BLS-D) providers to the first tier, the ratio was $53,000 per QALY with pump vehicles or $159,000 per QALY with ambulances. Change from a one-tier EMS to a two-tier EMS system by the addition of initial BLS/BLS-D providers in pump vehicles as the first tier was associated with a cost per QALY of $40,000. Change from one-tier EMS to two-tier EMS by the addition of initial BLS/BLS-D providers in ambulances as the first tier was associated with a cost per QALY of $94,000. Conclusion: The most attractive options in terms of incremental cost-effectiveness were improved response time in a two-tier EMS system or change from a one-tier to a two-tier EMS system. Future research should be directed toward identification of the costs of instituting the first tier of a two-tier EMS system and identification of cost-effective methods of improving response time. [Nichol G, Laupacis A, Stiell IG, O'Rourke K, Anis A, Bolley H, Detsky AS: Cost-effectiveness analysis of potential improvements to emergency medical services for victims of out-of- hospital cardiac arrest. Ann Emerg Med June 1996;27:711-720.] Article History: Received 29 June 1995; Revised 7 December 1995; Accepted 22 December 1995 Article Note: (footnote) [star] From the Clinical Epidemiology Unit, Loeb Medical Research Institute*, and the Division of General Internal Medicinea , Ottawa Civic Hospital, and the Division of Emergency Medicine, Department of Medicine, University of OttawaAs., Ottawa; and the Department of Health Administrationa[yen] and the Division of General Internal Medicine, Department of Medicinea[yen], University of Toronto, the Clinical Epidemiology Unit, Toronto Hospital#, and the Hospital Management Research Institute, Sunnybrook Health Science Centre**, Toronto, Ontario, Canada., [star][star] Supported in part by the Advanced Coronary Treatment Foundation, which received funding in part from the Asmund S Laerdal Foundation for Acute Medicine; and Physio-control Canada. Dr Detsky was supported by a National Health Research Scholar Award from Health and Welfare Canada. Dr Nichol was supported by a Palef Fellowship from Loeb Medical Research Institute, Ottawa Civic Hospital., a Address for reprints: Graham Nichol, MD, Clinical Epidemiology Unit, Ottawa Civic Hospital, 1053 Carling Avenue, Ottawa, Ontario Canada, K1Y 4E9, aa Reprint no. 47/1/72157

Byline: Graham Nichol, Allan S Detsky, Ian G Stiell, Keith O'Rourke, George Wells, Andreas Laupacis Abstract: Study objective: To determine the relative effectiveness of differences in response time interval, proportion of bystander CPR, and type and tier of emergency medical services (EMS) system on survival after out of hospital cardiac arrest. Methods: We performed a comprehensive literature search, excluding EMS systems other than those of interest (systems of interest were those comprising one tier with providers of basic life support [BLS] or advanced life support [ALS] and those comprising two tiers with providers of BLS or BLS-defibrillation followed by ALS), patient population of fewer than 100 cardiac arrests, studies in which we could not determine the total number of arrests of presumed cardiac origin, and studies lacking data on survival to hospital discharge. Metaanalysis using generalized linear model with dispersion estimation for random effects was then performed. Results: Increased survival to hospital discharge was significantly associated with tier (P Heart disease is the most common cause of death in the United States. Such deaths are often due to cardiac arrest, the sudden cessation of cardiac mechanical activity manifested by the absence of a detectable pulse, unresponsiveness, and lack of breathing. Emergency medical services (EMS) systems have evolved into multifaceted advanced cardiac life support systems involving CPR, defibrillation, artificial ventilation, intubation, and administration of medication. Controversy exists about the effectiveness of different methods of emergency cardiac care because of wide variation in reported survival among centers, ranging from 0% to 44%. This variation may be attributable to differences in the type of EMS system, proportion of victims receiving bystander CPR, response time intervals of providers, or geography of the city in question. Furthermore, different approaches to reporting survival make comparison of studies difficult. A consensus conference has offered guidelines for uniform reporting of results to facilitate comparison of results. The purpose of this analysis was to estimate the relative effectiveness of the type and tier of an EMS system, unit response time interval of providers, and rate of bystander CPR on survival after out-of-hospital cardiac arrest. Using a protocol developed a priori, we performed a metaanalysis based on conventional techniques. The protocol comprised selection criteria for the primary studies, definitions of the primary endpoints, and an analysis plan. The metaanalysis was part of a larger cost-effectiveness analysis of improvements to EMS systems for out-of-hospital cardiac arrest. The results of the cost-effectiveness analysis are reported elsewhere. Definitions of terms The organization of an EMS system may vary both in the degree of training of the health care providers, as well as in the number of vehicles responding to a medical emergency. No universally accepted nomenclature exists for categorizing EMS systems, and some terms may have different meanings for different people. To facilitate clarity and understanding, the following terms are defined. Emergency health care providers vary in the degree of their training and may or may not transport patients to the hospital. Basic life support (BLS) providers administer oxygen and CPR to victims of cardiac arrest. Providers of BLS with defibrillation (BLS-D) defibrillate patients using automated or manual defibrillators. Finally, advanced life support (ALS) providers are trained to perform endotracheal intubation and to administer IV medications. BLS or BLS-D level care may be provided by emergency medical technicians (EMTs) in ambulances or by firefighters in pump vehicles or vans. Generally, ALS care is only provided by EMTs in ambulances. These personnel are referred to by others as 'paramedics.' The team that responds to a cardiac arrest in a given city may be part of a one-tier or two-tier EMS system. In a one-tier EMS system, a single provider and vehicle type responds to medical emergencies. In a two-tier system, two types of providers and/or vehicles respond. The vehicles may include ambulances, which respond from ambulance bases; or pump vehicles or vans, which respond from fire stations. In two-tier EMS systems, BLS providers (first tier) usually arrive more quickly because more generally are serving a community. In American cities with two-tier EMS systems, the second responding providers (second tier) have ALS capability. About 75% of the American urban population is served by a two-tier rather than by a one-tier EMS system. In this analysis we considered five configurations of EMS systems: (1) one tier with BLS providers, (2) one tier with BLS-D providers, (3) one tier with ALS providers, (4) two tiers with BLS followed by ALS (BLS + ALS) providers, and (5) two tiers with BLS-D followed by ALS (BLS-D + ALS) providers. Article History: Received 29 June 1995; Revised 18 December 1995; Accepted 18 January 1996 Article Note: (footnote) [star] From the Clinical Epidemiology Unit, Loeb Medical Research Institute*, and the Division of General Internal Medicinea , Ottawa Civic Hospital, and the Division of Emergency Medicine, Department of MedicineAs., University of Ottawa, Ottawa; and the Department of Health Administrationa[yen] and the Division of General Internal MedicineA[paragraph], University of Toronto, and the Clinical Epidemiology Unit, The Toronto Hospital#, Toronto, Ontario, Canada., [star][star] Supported in part by the Advanced Coronary Treatment Foundation of Canada, which received funding in part from the Asmund S Laerdal Foundation for Acute Medicine and from Physio-control Canada. Dr Nichol was supported by a Palef Fellowship from the Loeb Medical Research Institute. Dr Detsky is supported by a National Health Research Scholar Award from Health and Welfare Canada. Dr Laupacis and Dr Stiell are supported by MRC Scientist Awards from the Medical Research Council of Canada., a Address for reprints Graham Nichol, MD, Clinical Epidemiology Unit, Loeb Medical Research Institute, Ottawa Civic Hospital, 1053 Carling Avenue, Ottawa, Ontario, Canada, K1Y 4E9, aa Reprint no. 47/1/73317

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.annemergmed.2009.01.021 Byline: Graham Nichol (a), Ella Huszti (b), Alice Birnbaum (c), Brian Mahoney (d), Myron Weisfeldt (e), Andrew Travers (f), Jim Christenson (g), Karen Kuntz (h) Abstract: Our objective is to evaluate the incremental cost-effectiveness of use of cardiopulmonary resuscitation (CPR) and automated external defibrillators (AEDs) by lay responders (CPR+AED) versus CPR only for cardiac arrest during a multicenter randomized trial. Author Affiliation: (a) University of Washington, Seattle, WA (b) McGill University, Montreal, Quebec, Canada (c) Axio Research Inc., Seattle, WA (d) University of Minnesota, Minneapolis, MN (e) Johns Hopkins University, Baltimore, MD (f) Dalhousie University, Halifax, Nova Scotia, Canada (g) University of British Columbia, Vancouver, British Columbia, Canada (h) Harvard School of Public Health, Boston, MA Article History: Received 9 May 2007; Revised 29 August 2007; Revised 30 April 2008; Revised 21 October 2008; Revised 5 December 2008; Accepted 21 January 2009 Article Note: (footnote) Provide feedback on this article at the journal's Web site, www.annemergmed.com., Supervising editor: Theodore R. Delbridge, MD, MPH, Author contributions: GN, EH, and KK conceived the study, designed the trial, and obtained research funding. GN, EH, and AB supervised the conduct of the trial and data collection. AB undertook recruitment of participating centers and patients and managed the data, including quality control. EH, AB, and KK provided statistical advice on study design and analyzed the data. GN drafted the article, and all authors contributed substantially to its revision. GN takes responsibility for the paper as a whole., Funding and support: By Annals policy, all authors are required to disclose any and all commercial, financial, and other relationships in any way related to the subject of this article, that might create any potential conflict of interest. See the Manuscript Submission Agreement in this issue for examples of specific conflicts covered by this statement. For full disclosures, see , available at http://www.annemergmed.com., Publication date: Available online March 25, 2009.

Objective: To determine whether the risk of falling (with a possible increased chance of subdural hematoma) should influence the choice of antithrombotic therapy in elderly patients with atrial fibrillation. Design: A Markov decision analytic model was used to determine the preferred treatment strategy (no antithrombotic therapy, long-term aspirin use, or long-term warfarin use) for patients with atrial fibrillation who are 65 years of age and older, are at risk for falling, and have no other contraindications to antithrombotic therapy. Input data were obtained by systematic review of MEDLINE. Outcomes were expressed as quality-adjusted life-years. Results: For patients with average risks of stroke and falling, warfarin therapy was associated with 12.90 quality-adjusted life-years per patient; aspirin therapy, 11.17 quality-adjusted life-years; and no antithrombotic therapy, 10.15 quality-adjusted life-years. Sensitivity analysis demonstrated that, regardless of the patients' age or baseline risk of stroke, the risk of falling was not an important factor in determining their optimal antithrombotic therapy. Conclusions: For elderly patients with atrial fibrillation, the choice of optimal therapy to prevent stroke depends on many clinical factors, especially their baseline risk of stroke. However, patients' propensity to fall is not an important factor in this decision. Arch Intern Med. 1999;159:677-685