bluuebunny/crossref_metadata_2025 huggingface dataset:
How HIV Treatment Advances Affect the Cost—Effectiveness of Prevention
Authors: Pinkerton Steven D. , Holtgrave David R.
Published: March 2007

Objective. The cost-effectiveness of an HIV prevention program depends, in part, on its potential to avert HIV-related medical care costs. Recent advances in antiretroviral therapy have made HIV/AIDS treatment both more effective and more costly, which might make HIV prevention either more or less cost-effective. The objective of the present study was to explicate the relationship between the effectiveness and costs of HIV treatment and the cost-effectiveness of HIV prevention programs. Methods. A basic analytic framework was used to compare the cost-effectiveness of HIV prevention interventions with respect to different HIV/AIDS medical care scenanos. Algebra was used to calculate a cost-effectiveness threshold that distinguishes prevention programs that become more cost-effective when therapeutic advances simultaneously increase or decrease the cost and effectiveness of treatment from those that become less cost-effective. Recent estimates of the costs and consequences of combination antiretroviral therapy were used to illustrate the calculation method. Results. The advent of combination antiretroviral therapies for HIV has increased the cost-effectiveness of some, but not all, HIV prevention interventions. Conclusions. Whether a particular prevention program becomes more or less cost-effective as a consequence of advancements in the medical treatment of HIV/AIDS depends upon the specific characteristics of both the program and the therapy. Key words: HIV prevention; treatment; cost-effectiveness analysis. (Med Decis Making 2000;20:89-94)
Comparison of Finnish and U.S.-based Visual Analog Scale Valuations of the EQ-5D Measure
Authors: Johnson Jeffrey A. , Ohinmaa Arto , Murti Bhisma , Sintonen Harri , Coons Stephen Joel
Published: March 2007

The EQ-5D is a multiattribute health status measure that can be used to derive preference-based index scores for health-related quality-of-life (HRQOL) assessment. Valuations for EQ-5D health states using different techniques have been obtained in a number of countries. It is not clear how valuations from different countries compare. Using an ordinary least-squares regression, visual analog scale valuations for EQ-5D health states obtained in postal surveys in Finland and the United States were compared. The regression model estimates indicated that Finnish and U.S. respondents did provide different preference valuations for different levels of health. However, the country-specific differences were not large and depended on the dimension and the level of problem on that dimension. Differences in health-state valuations are unlikely to have important implications when using the EQ-5D in international studies. Key words: EQ-5D; valuations; health-related quality of life; visual analog scale; health status. (Med Decis Making 2000;20:281-289)
Representing Both First- and Second-order Uncertainties by Monte Carlo Simulation for Groups of Patients
Authors: Halpern Elkan F. , Weinstein Milton C. , Hunink Maria G.M. , Gazelle G. Scott
Published: March 2007

Actual implementation of probabilistic sensitivity analysis may lead to misleading or improper conclusions when it is applied to groups of patients rather than individual patients. The practice of combining first- and second-order simulations when modeling the outcome for a group of more than one patient yields an erroneous marginal distribution whenever the parameter values are randomly sampled for each patient while the results are presented as simulated means for the group of patients. This practice results in underrepresenting the second-order uncertainty. It may also distort the shape (especially the symmetry or extent of the tails) in the simulated distribution. As a result, it may lead to premature or incorrect conclusions of superiority. It may also result in inappropriate estimates of the value of further research to inform parameter values. Key words: Simulation; probabilistic sensitivity analysis; Monte Carlo; confidence interval ; cost-effectiveness; implementation. (Med Decis Making 2000;20:314-322)
Comparing Three-class Diagnostic Tests by Three-way ROC Analysis
Authors: Dreiseitl Stephan , Ohno-Machado Lucila , Binder Michael
Published: March 2007

Three-way ROC surfaces are based on a generalization of dichotomous ROC analysis to three-class diagnostic tests. The discriminatory power of three-class diagnostic tests is measured by the volume under the ROC surface. This measure can be given a probabilistic interpretation similar to the equivalence of the c-index to the area under the ROC curve. This article presents a method to calculate nonparametric estimates of the variance of the volume under the surface using Mann-Whitney U statistics. As a simple extension of this result, it is possible to calculate covariance estimates for the volume under the surface. This allows the statistical comparison of two tests used for diagnostic tasks with three possible outcomes. The formulas derived are validated on synthetic data and applied to a three-class data set of pigmented skin lesions. It is shown that a neural network algorithm trained on clinical data and lesion features performs better than one trained on only the lesion features. Key words: Receiver operating characteristic curves; trichotomous ROC analysis. (Med Decis Making 2000; 20:323-331)
Decision Analysis with Cumulative Prospect Theory
Authors: Bayoumi Ahmed M. , Redelmeier Donald A.
Published: March 2007

Background. Individuals sometimes express preferences that do not follow expected utility theory. Cumulative prospect theory adjusts for some phenomena by using decision weights rather than probabilities when analyzing a decision tree. Methods. The authors examined how probability transformations from cumulative prospect theory might alter a decision analysis of a prophylactic therapy in AIDS, eliciting utilities from patients with HIV infection (n = 75) and calculating expected outcomes using an established Markov model. They next focused on transformations of three sets of probabilities : 1) the probabilities used in calculating standard-gamble utility scores; 2) the probabilities of being in discrete Markov states; 3) the probabilities of transitioning between Markov states. Results. The same prophylaxis strategy yielded the highest quality-adjusted survival under all transformations. For the average patient, prophylaxis appeared relatively less advantageous when standard-gamble utilities were transformed. Prophylaxis appeared relatively more advantageous when state probabilities were transformed and relatively less advantageous when transition probabilities were transformed. Transforming standard-gamble and transition probabilities simultaneously decreased the gain from prophylaxis by almost half. Sensitivity analysis indicated that even near-linear probability weighting transformations could substantially alter quality-adjusted survival estimates. Conclusion. The magnitude of benefit estimated in a decision-analytic model can change significantly after using cumulative prospect theory. Incorporating cumulative prospect theory into decision analysis can provide a form of sensitivity analysis and may help describe when people deviate from expected utility theory. Key words: decision analysis; cumulative prospect theory; expected utility theory ; standard gamble. (Med Decis Making 2000;20:404-412)
Electronic Trial Banks: A Complementary Method for Reporting Randomized Trials
Authors: Sim Ida , Owens Douglas K. , Lavori Philip W. , Rennels Glenn D.
Published: March 2007

Background. Randomized clinical trial (RCT) results are often difficult to find, interpret, or apply to clinical care. The authors propose that RCTs be reported into electronic knowledge bases—trial banks—in addition to being reported in text. What information should these trial-bank reports contain? Methods. Using the competency decomposition method, the authors specified the ideal trial-bank contents as the information necessary and sufficient for completing the task of systematic reviewing. Results. They decomposed the systematic reviewing task into four top-level tasks and 62 subtasks. 162 types of trial information were necessary and sufficient for completing these subtasks. These items relate to a trial's design, execution, administration, and results. Conclusion. Trial-bank publishing of these 162 items would capture into computer-understandable form all the trial information needed for critically appraising and synthesizing trial results. Decision-support systems that access shared, up-to-date trial banks could help clinicians manage, synthesize, and apply RCT evidence more effectively. Key words: electronic publishing; knowledge bases; clinical trials; meta-analysis. (Med Decis Making 2000;20:440-450)
Validation of a Decisional Conflict Scale
Authors: O'Connor Annette M.
Published: March 2007

The study objective was to evaluate the psychometric properties of a decisional conflict scale (DCS) that elicits: 1) health-care consumers' uncertainty in making a health-related decision; 2) the factors contributing to the uncertainty; and 3) health-care consumers' perceived ef fective decision making. The DCS was developed in response to the lack of instruments available to evaluate health-care-consumer decision aids and to tailor decision-supporting interventions to particular consumer needs. The scale was evaluated with 909 individuals deciding about influenza immunization or breast cancer screening. A subsample of respon dents was retested two weeks later. The test-retest reliability coefficient was 0.81. Internal consistency coefficients ranged from 0.78 to 0.92. The DCS discriminated significantly (p < 0.0002) between those who had strong intentions either to accept or to decline invitations to receive influenza vaccine or breast cancer screening and those whose intentions were uncertain. The scale also discriminated significantly (p < 0.0002) between those who ac cepted or rejected immunization and those who delayed their decisions to be immunized. There was a weak inverse correlation (r = - 0.16, p < 0.05) between the DCS and knowledge test scores. The psychometric properties of the scale are acceptable. It is feasible and easy to administer. Evaluations of responsiveness to change and validation with more difficult decisions are warranted. Key words: measurement; decision making; immunization; breast cancer screening. (Med Decis Making 1995;15:25-30)
Information Seeking in Primary Care
Authors: Gorman Paul N. , Helfand Mark
Published: March 2007

Primary care physicians have many questions about optimal care while they are seeing patients, but they pursue only about 30% of their questions. The authors designed a study to determine the factors that motivate physicians to pursue answers to some of their ques tions, while leaving the majority of their questions unanswered. They interviewed 49 non- academic primary care physicians during office hours to record clinical questions as they arose in the course of patient care. The physicians then recorded their perceptions of each question with respect to 12 factors expected to motivate information seeking. Two to five days after the interview, each physician was telephoned to determine which questions had been pursued. In a multiple logistic-regression model only two factors were significant pre dictors of pursuit of new information: the physician's belief that a definitive answer existed, and the urgency of the patient's problem. Other factors, including the difficulty of finding the answer, potential malpractice liability, potential help or harm to the patient, and self-perceived knowledge of the problem, were not significant in the model. Primary care physicians are significantly more likely to pursue answers to their clinical questions when they believe that definitive answers to those questions exist, and when they perceive the patient's problem to be urgent. Medical information systems must be shown to have direct and immediate benefits to solving the problems of patient care if they are to be more widely used by practitioners. Key words: information seeking; primary care; motivation; psychology; decision making. (Med Decis Making 1995;15:113-119)
A New Model for Category-scaling Data with an Application to the Development of Health-status Measures
Authors: Damiano Anne M. , Epstein Leonardo D. , Mackenzie Ellen J.
Published: March 2007

Category rating is used to assess patient, family-member, provider, and societal preferences for health outcomes. Often, it is of interest to compare ratings obtained from different groups. Standard methods for making comparisons, such as regressions, correlations, and multiple t-tests, do not account for the dependency among ratings. The authors propose a new model for category ratings that does consider their relative dependency. This model provides a profile of ratings for a single group and facilitates comparisons across groups. It was applied to category ratings for four levels of Bending and Lifting function as defined by the recently developed Functional Capacity Index (FCI). Differences in ratings were observed across groups with different personal experiences of functional limitations and across groups with different degrees of clinical knowledge. These differences were not observed when standard methods were used. Thus, ignoring the relative nature of category ratings can lead to different conclusions about group preferences for health outcomes. When the ratings are being used to scale a health-status measure, this discrepancy has implications for the application of the measure in resource allocation. Key words: category scaling; health status measures. (Med Decis Making 1995;15:170-179)
Explaining Distortions in Utility Elicitation through the Rank-dependent Model for Risky Choices
Authors: Wakker Peter , Stiggelbout Anne
Published: March 2007

The standard-gamble (SG) method has been accepted as the "gold standard" for the elic itation of utility when risk or uncertainty is involved in decisions, and thus for the measurement of utility in medical decisions. It is based on the assumptions of expected-utility theory. Unfortunately, there is now abundant evidence that expected utility is not empirically valid, and that the SG method overestimates risk aversion and the utilities of impaired health states. This paper shows how rank-dependent utility theory, a newly developed theory in decision science, can explain the main violations of expected utility. Thus it provides a means for correcting the SG method and for improving the assessments of quality-adjusted life years for medical decisions in which there is uncertainty about outcomes. Key words: health- state utility; risk aversion; rank dependence; medical decision making; standard gamble. (Med Decis Making 1995;15:180-186)
Threshold Analysis and Programs for Prevention of HIV Infection
Authors: Holtgrave David R. , Qualls Noreen L.
Published: March 2007

Background. Measuring the economic effectiveness of HIV-infection prevention activities poses special challenges in terms of behavioral change and health outcomes assessment. Methods. One way to address this difficulty is to employ threshold analysis to determine a level of cost per HIV infection averted above which society would seem unwilling to pay. The authors employ a cost-utility analytic framework to determine a monetary threshold for HIV prevention programs, subject base-case results to sensitivity analyses, and apply these results to the Centers for Disease Control and Prevention's fiscal year 1993 budget for extramural HIV prevention programs. Results. The monetary threshold for cost per HIV infection averted was calculated to be $417,000 in 1993 dollars, and ranged from $185,000 to $648,000 depending upon the dollar amount society would be willing to pay per quality- adjusted life year gained. Conclusions. Economic evaluations of particular HIV-infection prevention activities at least can begin by determining whether their levels of effectiveness are above or below this derived monetary threshold, and refinements beyond this dichoto mous evaluation can proceed as further data become available. Key words: HIV; AIDS; prevention; threshold analysis; cost-utility analysis. (Med Decis Making 1995;15:311-317)
Using Cluster Analysis for Medical Resource Decision Making
Authors: Dilts David , Khamalah Joseph , Plotkin Ann
Published: March 2007

Escalating costs of health care delivery have in the recent past often made the health care industry investigate, adapt, and apply those management techniques relating to budgeting, resource control, and forecasting that have long been used in the manufacturing sector. A strategy that has contributed much in this direction is the definition and classification of a hospital's output into "products" or groups of patients that impose similar resource or cost demands on the hospital. Existing classification schemes have frequently employed cluster analysis in generating these groupings. Unfortunately, the myriad articles and books on clustering and classification contain few formalized selection methodologies for choosing a technique for solving a particular problem, hence they often leave the novice investigator at a loss. This paper reviews the literature on clustering, particularly as it has been applied in the medical resource-utilization domain, addresses the critical choices facing an investigator in the medical field using cluster analysis, and offers suggestions (using the example of clustering low-vision patients) for how such choices can be made. Key words: cluster analysis decisions; resource classification schemes; clustering methodology. (Med Decis Making 1995;15:333-347)
Rank-order Stability Analysis (ROSA)
Authors: Einarson Thomas R. , Arikian Steven R. , Doyle John J.
Published: March 2007

In a pharmacoeconomic analysis, the validity of findings is critical because product ranking may influence formulary decision making. The authors present an approach for examining uncertainty in a pharmacoeconomic analysis that parallels the confidence-interval approach to statistical analysis. This method, rank-order stability analysis (ROSA), is a clear and comprehensive method for validating results of a pharmacoeconomic analysis, as it identifies and evaluates all inputs and values. It is a break-even analysis that identifies the specific point of insensitivity for all parameters analyzed in the pharmacoeconomic model. ROSA is proposed as the preferred method for judging the validity of results derived from estimated parameters in pharmacoeconomic analyses. Key words: pharmacoeconomic analysis; sen sitivity analysis; robustness; cost-effectiveness analysis; rank-order stability analysis. (Med Decis Making 1995;15:367-372)
When Do the "Dollars" Make Sense?
Authors: O'Brien Bernie , Gafni Amiram
Published: March 2007

There is growing interest in the application of cost-benefit analysis (CBA) as a tech nique for the economic evaluation of health care programs. A distinguishing feature of CBA is that costs and benefits are expressed in the same units of value—typically money. A popular method for estimating money values for health care programs is the use of willingness-to-pay (or accept) survey techniques known as contingent valuation. This paper presents a conceptual framework to help in the interpretation or design of contingent valuation studies in health care. To be consistent with the theory upon which CBA is built, the authors consider what types of questions should be asked of what populations. They conclude that studies undertaking contingent valuation should dis tinguish between compensating variation and equivalent variation, and recognize that respondents can be gainers or losers in utility and therefore should be asked willing ness-to-pay (or accept) questions as appropriate. Current critical-appraisal guidance in the health care literature for CBA is poor and unlikely to offer useful demarcation between good and bad CBA studies. More work is needed exploring whether recently issued guidelines for contingent valuation in environmental damage assessment are applicable to health care studies. Key words: cost-benefit analysis; contingent valu ation ; willingness to pay. (Med Decis Making 1996;16:288-299)
The Discrepancy between Daily Practice and the Policy of a Decision-analytic Model
Authors: Timmermans Danielle R.M. , Sprij Arwen J. , De Bel Chris E.
Published: March 2007

The optimal treatment of children with fever of unknown origin is controversial, in spite of two decision analyses that advise treatment with antibiotics for all such children. The aim of this study was to analyze the differences between pediatricians' diagnostic and therapeutic decisions and the outcomes of the decision-analytic models. Thirty- six pediatricians were asked to evaluate 30 patient cases and to give their diagnostic and therapeutic judgments. In addition, the pediatricians were asked questions about the epidemiology of fever of unknown origin. Analyses showed that the differences in policy between pediatricians and the models could not be explained by the reasons mentioned in the literature, i.e., 1) differences in epidemiologic data used, 2) differ ences in the weighting of clinical information, and 3) differences in the evaluation of outcomes. The differences in policy might be due to a difference between the objective of the models and pediatricians' aim. In a curative setting, pediatricians are not trying to prevent meningitis (or another serious disease) by treating possible occult bacter emia, but rather aim to detect meningitis in an early stage. A decision analysis deter mining the most cost-effective strategy for early detection of meningitis might therefore be more easily accepted by pediatricians. Key words: diagnostic and therapeutic de cisions ; decision-analytic models; fever of unknown origin. (Med Decis Making 1996; 16:357-366)
Neural Networks in Clinical Medicine
Authors: Penny Will , Frost David
Published: March 2007

Neural networks are parallel, distributed, adaptive information-processing systems that develop their functionality in response to exposure to information. This paper is a tutorial for researchers intending to use neural nets for medical decision-making applications. It includes detailed discussion of the issues particularly relevant to medical data as well as wider issues relevant to any neural net application. The article is restricted to back-propagation learning in multilayer perceptrons, as this is the neural net model most widely used in medical applications. Key words: neural networks; medical decision making; pattern recognition; nonlinearity; error back-propagation; multi layer perceptron. (Med Decis Making 1996;16:386-398)
Assessing Rater Performance without a "Gold Standard" Using Consensus Theory
Authors: Weller Susan C. , Mann N. Clay
Published: March 2007

This study illustrates the use of consensus theory to assess the diagnostic perform ances of raters and to estimate case diagnoses in the absence of a criterion or "gold" standard. A description is provided of how consensus theory "pools" information pro vided by raters, estimating rater competencies and differentially weighting their re sponses. Although the model assumes that raters respond without bias (i.e., sensitivity = specificity), a Monte Carlo simulation with 1,200 data sets shows that model esti mates appear to be robust even with bias. The model is illustrated on a set of elbow radiographs, and consensus-model estimates are compared with those obtained from follow-up data. Results indicate that with high rater competencies, the model retrieves accurate estimates of competency and case diagnoses even when raters' responses are biased. Key words: clinical competence; interobserver variation; diagnostic evalu ation ; models—mathematical; consensus theory. (Med Decis Making 1997;17:71- 79)
Good Technologies Gone Bad
Authors: Phelps Charles E.
Published: March 2007

Cost-effectiveness (CE) ratios vary considerably, not only across interventions, but within single interventions. Using a simple decision-tree model of the treat-vs no-treat decision to organize the analysis, four potential errors leading to these within-treatment differences in CE ratios are identified. These errors arise from estimates relating to 1) prior probabilities of disease; 2) treatment efficacies; 3) costs of treatment; and 4) patient preferences. Systematic biases, where present, suggest overuse of medical interventions. For diagnostic tests, two additional potential sources of error are con sidered (using a simple decision tree incorporating both test and treat decisions). These involve 5) sensitivity and specificity of the diagnostic test and 6) inappropriate choice of "cutoff" to determine abnormal patients, in part arising from errors in esti mating prior probability of disease. Key words: cost-effectiveness; biases; errors; re source use; utilities. (Med Decis Making 1997;17:107-117)
An Experimental Test of a Theoretical Foundation for Rating-scale Valuations
Authors: Bleichrodt Han , Johannesson Magnus
Published: March 2007

A major advantage of using a rating scale in health-utility measurement is its practical applicability: the method is relatively easy to understand, and various health states can be assessed simultaneously. However, a theoretical foundation for rating-scale valuations has not been established. The primary aim of this paper is to present a theoretical foundation for rating-scale valuations based on the theory of measurable value functions and to provide a consistency test to see whether rating-scale valuations do indeed elicit a measurable value function. If rating-scale valuations elicit a measurable value function, then Dyer and Sarin have shown how they are related to von Neumann-Morgenstern (vNM) utilities. The appropriate technique to measure vNM utilities is the standard gamble. Torrance has suggested that rating-scale valuations and standard-gamble valuations are related by a power function. A secondary aim of this paper is to examine the relationship between rating-scale valuations and standard-gamble valuations hypothesized by Torrance. An experiment was designed to test consistency of rating-scale valuations and the relationship between rating-scale valuations and standard-gamble valuations. The experiment tested whether rating-scale valuations are independent of the context in which they are elicited, as they should be if they elicit points on a measurable value function. 80 Swedish and 92 Dutch respondents participated in the experiment. The results showed that rating-scale valuations depend on the number of preferred alternatives in the task and thus violate a basic property of measurable value functions. The estimation of the power function did not result in stable results: parameter estimates varied, in some cases there was indication of misspecification, and in most cases there was indication of heteroskedastic errors. The implications of these findings for the common use of rating-scale valuations in cost-utility analysis are serious: the dependency of the rating-scale valuations on the other health states included in the task casts serious doubts on the validity of the rating-scale method. Key words: QALYs; rating scale; cost-utility analysis; medical decision making. (Med Decis Making 1997;17:208-216))
Cardiologists' Use of Clinical Information for Management Decisions for Patients with Unstable Angina:
Authors: Van Miltenburg-Van Zijl Addy J.M. , Bossuyt Patrick M.M. , Nette Robert W. , Simoons Maarten L. , Taylor Thomas R.
Published: March 2007

Previous studies of management of unstable angina have revealed substantial differences in management between different hospitals, especially with respect to the use of coronary angiography. Physicians in a hospital with angiography facilities were more inclined to perform angiography than were physicians in hospitals without these facilities, even when differences in patient populations were taken into account. The authors compared the management strategies of 18 cardiologists, working in hospitals with and without angiography facilities, using a series of paper-case summaries, in order to assess the contribution of individual variability between physicians to practice differences. Physicians who worked in a hospital with in-house angiography facilities were more inclined to request angiography in similar case summaries, but the inter-individual variation exceeded the between-hospital variation. The variation in individual policies with respect to the decision to initiate coronary angiography could be associated with differences in weighting clinical information. These results confirm that practice variations may have many causes: variability in patients' characteristics, variations in how physicians react to these, differences in the availability of services, and variability in thresholds for action. Key words: unstable angina; coronary angiography; policy analysis; practice variation. (Med Decis Making 1997;17:292-297)
A Survey of Clinicians' Opinions Regarding the Value of Published Decision Analyses as Sources of Clinically Useful Information
Authors: Dolan James G.
Published: March 2007

Published decision analyses avoid many of the practical problems thought to be con tributing to the slow acceptance of clinical decision analysis. To assess clinicians' opinions regarding the usefulness of published decision analyses, 46 physicians at a large community teaching hospital judged how useful 13 proposed interventions would be in helping them make better clinical decisions. Although 48% of the respondents indicated that they clearly understood decision analysis, easy access to a published decision analysis was the lowest-ranked intervention, with 28% of the respondents indicating that it would be helpful. In contrast, 87% indicated that easy access to the latest review article, the highest-rated intervention, would be helpful. This finding sug gests that the proposed practical barners to the acceptance of clinical decision analysis are relatively ummportant. The success of efforts to foster clinical decision analysis will depend on the identification of the key factors impeding its acceptance by clinicians and the development of effective techniques to overcome them. Key words: decision analysis, continmng medical education. (Med Decis Making 1997;17:427-430)
An International Comparison of Physicians' Judgments of Outcome Rates of Cardiac Procedures and Attitudes toward Risk, Uncertainty, Justifiability, and Regret
Authors: Poses Roy M. , De Saintonge D. Mark Chaput , Mcclish Donna K. , Smith Wally R. , Huber Elizabeth C. , Clemo F. Lynne W. , Schmitt Brian P. , Alexander-Forti Donna , Racht Edward M. , Colenda Christopher C. , Centor Robert M.
Published: March 2007

Objective. Compare U.K. and U.S. physicians' judgments of population probabilities of important outcomes of invasive cardiac procedures; and values held by them about risk, uncertainty, regret, and justifiability relevant to utilization of cardiac treatments. Design. Cross-sectional study. Setting. University hospital and VA medical center in the United States; two teaching hospitals in the United Kingdom. Participants. 171 housestaff and attendings at U.S. teaching hospitals; 51 physician trainees and consultants at U.K. hospitals. Measures. Judgments of probabilities of severe complications and deaths due to Swan-Ganz catheterization, cardiac catheterization, percutaneous transluminal coronary angioplasty (PTCA), and coronary artery bypass grafting (CABG); judgments of malpractice risks for case vignettes; Nightingale's risk-aversion instrument; Gerrity's reaction-to-uncertainty instrument; questions about need to justify decisions; responses to case vignettes regarding regret. Results. The U.S. physicians judged rates of two bad outcomes of cardiac procedures (complications due to cardiac catheterization; death due to CABG) to be significantly higher (p ≤ 0.01) than did the U.K. physicians (U.S. medians, 5 and 3.5, respectively; U.K. medians 3 and 2). The median ratio of (risk of malpractice suit I error of omission)/(risk of suit I error of commission) judged by U.K. physicians, 3, was significantly (p = 0.0006) higher than that judged by U.S. physicians, 1.5. The U.K. physicians were less often risk-seeking in the context of possible losses than the U.S. physicians (odds ratio for practicing in the U.K. as a predictor of risk seeking 0.3, p = 0.003). The U.K. physicians had significantly more discomfort with uncertainty than did the U.S. physicians, as reflected by higher scores on the stress scale (U.K. median 48, U.S. 42, p = 0.0001) and the reluctance-to-disclose-uncertainty scale (U.K. 40, U.S. 37, p < 0.0001) of the Gerrity instrument. There was no clear international difference in perceived need to justify decisions, or in regret. Conclusions. The results were not clearly consistent with the uncertainty hypothesis that international practice variation is due to differences in judged rates of outcomes of therapy or with the imperfect-agency hypothesis that practice variation is due to differences in physicians' personal values. The causes and implications of practice variations remain unclear.
The Association of Physician Attitudes about Uncertainty and Risk Taking with Resource Use in a Medicare HMO
Authors: Allison Jeroan J. , Kiefe Catarina I. , Cook E. Francis , Gerrity Martha S. , Orav E. John , Centor Robert
Published: March 2007

Purpose. To explore the association between the attitudes of primary care physicians toward uncertainty and risk taking, as measured by a validated survey, with resource use in a Medicare HMO. Design. All primary-care internists (n = 20) in a large, multi- specialty clinic were surveyed to measure their attitudes about uncertainty and risk taking using three previously developed scales. Results were linked with administrative data for 792 consecutive patients in a recently created Medicare HMO. The patients' index visits occurred between April 1, 1995, and November 30, 1995. Analysis. Charges stemming from several claim types (primary care and subspecialty physician, laboratory, radiology, and ambulatory procedures) in the 30 days following the index visit were summed. The physician scales were dichotomized at the median to seek unadjusted associations with charges. Generalized estimation equations were used to account for the correlation of charges resulting from patients' being nested within phy sicians and adjusted for physician characteristics (age, sex, years in practice) and patient characteristics (age, sex, comorbidity). Main results. The physician response rate was 90%. Most physicians (90%) were male. The mean age of the patients was 74 years, and 69% were female. The mean cost (±SD) per patient was $621.61 ± 1,737.31. From the unadjusted analysis, high "anxiety due to uncertainty" was asso ciated with higher patient charges ($197.85 vs $158.21, p = 0.01). From the multivar iable analysis, each standard deviation increase in "anxiety due to uncertainty" (3.5 points) corresponded to a 17% increase in mean charges (p < 0.01) and each similar increase in "reluctance to disclose uncertainty to patients" (1.92 points) corresponded to a 12% increase (p = 0.03). However, increasing "reluctance to disclose mistakes to physicians" and increasing physician risk-taking propensity were associated with decreased total charges [-10% per standard deviation (1.34 points), p = 0.02, and -8% per standard deviation (3.26 points), p = 0.02, respectively]. Conclusion. Physi cian attitudes toward uncertainty were significantly associated with patient charges. Further investigation may improve prediction of patient-care charges, offer insight into the medical decision-making process, and perhaps clarify the relationship between cost, uncertainty, and quality of care. Key words: physician uncertainty; risk taking; managed care; medical charges. (Med Decis Making 1998;18:320-329)
A Practice Pathway for the Initial Diagnostic Evaluation of Isolated Sixth Cranial Nerve Palsies
Authors: Miller Ruth W. , Lee Andrew G. , Schiffman Jade S. , Prager Thomas C. , Garza Raymund , Jenkins Patricia F. , Sforza Paul , Verm Alan , Kaufman David , Robinson Wendy , Eggenberger Eric , Tang Rosa A.
Published: March 2007

Purpose: To define a practice pathway for the evaluation of sixth-nerve palsies (SNPs) and to determine its cost—effectiveness and validity in a retrospective chart review. Methods: A Medline search of the English-language literature from 1966 to 1995 was performed to define the available clinical evidence and develop the practice pathway. The authors retrospectively reviewed 407 charts with the diagnosis of SNP seen at three centers. Information obtained included: etiologic diagnosis if known; development of new neurologic or ophthalmologic findings; and results and costs of neuroimaging studies, if performed. Results: Of the 407 patients, 98 underwent computed tomogra phy scans and 212 underwent magnetic resonance imaging of the head. Eighty cases were non-isolated, 317 were isolated SNP, and ten could not be classified from chart information. Of the 317 cases of isolated SNP, 49 were classified as traumatic; 5, congenital; 158, vasculopathic; 63, nonvasculopathic; and 42, progressive or unre solved. Following the recommendations of the practice pathway, the 158 patients clas sified as having vasculopathic SNP would not have undergone neuroimaging studies, realizing a savings of $100,000 in this study population of 407 patients. Conclusion: The recommendations of the practice pathway are supported by review of the literature and the retrospective review of these cases. However, a prospective study with a matched control group is needed to demonstrate regional and specialty-specific van ations in care and to strengthen the clinical certainty of the pathway recommendations. Key words: practice pathway; diagnostic evaluation; sixth cranial nerve palsies; oph thalmology. (Med Decis Making 1999;19:42-48)
Conventional and Chained Standard Gambles in the Assessment of Coronary Heart Disease Prevention and Treatment
Authors: Lalonde Lyne , Clarke Ann E. , Joseph Lawrence , Grover Steven A.
Published: March 2007

The authors compared the abilities of descriptive and valuational health-related quality- of-life measures to discriminate healthy participants (n = 39) from those on diets for dyslipidemia (n = 35) and angina patients (n = 30). On the rating scale, the time tradeoff, and the General Health Perception subscale of the SF-36 Health Survey, the participants with dyslipidemia or angina reported lower mean scores than the healthy participants. No differences were detected between these groups on conventional or chained standard gamble (SG) scales. The distribution of the conventional and the chained SG scores was very skewed, with the vast majority of scores being equal or very close to the maximum score. It is concluded that in this study the discriminant ability of the chained SG was comparable to that of the conventional SG and inferior to descriptive and non-risky valuational scaling techniques. This may be explained by the distortion of probabilities, by a misunderstanding of the SG chained assessment, and by a strong certainty effect. Key words: dyslipidemia; coronary heart disease pre vention; angina; health-related quality of life; health status; SF-36 Health Survey; va lidity. (Med Decis Making 1999;19:149-156)
Reliability Block Diagrams to Model Disease Management
Authors: Sonnenberg Amnon , Inadomi John M. , Bauerfeind Peter
Published: March 2007

Background and objectives. Studies of diagnostic or therapeutic procedures in the management of any given disease tend to focus on one particular aspect of the disease and ignore the interaction between the multitude of factors that determine its final outcome. The present article introduces a mathematical model that accounts for the joint contribution of various medical and non-medical components to the overall dis ease outcome. Methods. A reliability block diagram is used to model patient compli ance, endoscopic screening, and surgical therapy for dysplasia in Barrett's esophagus. Results. The overall probability of a patient with a Barrett's esophagus to comply with a screening program, be correctly diagnosed with dysplasia, and undergo successful therapy is 37%. The reduction in the overall success rate, despite the fact that the majority of components are assumed to function with reliability rates of 80% or more, is a reflection of the multitude of serial subsystems involved in disease management. Each serial component influences the overall success rate in a linear fashion. Building multiple parallel pathways into the screening program raises its overall success rate to 91%. Parallel arrangements render systems less sensitive to diagnostic or thera peutic failures. Conclusions. A reliability block diagram provides the means to model the contributions of many heterogeneous factors to disease outcome. Since no medical system functions perfectly, redundancy provided by parallel subsystems assures a greater overall reliability. Key words: Barrett's esophagus; decision analysis; outcome research; reliability block diagram; sensitivity analysis; screening endoscopy. (Med De cis Making 1999;19:180-185)
Implicit Valuation of a Blood-exclusion Decision
Authors: Kaplan Edward H.
Published: March 2007

This paper presents an implicit valuation of Israel's decision to exclude blood donations from Ethiopian immigrants. The approach adopts assumptions that deliberately over state the public health effectiveness of this policy, for if such an analysis fails to justify exclusion on public health grounds, nothing will. Building on a recent (over)estimate of the number of infectious donations prevented by the ban, the analysis considers the cost of HIV-infectious donations entering the blood supply, the benefits of healthy do nations, and the cost of needlessly screening blood that will be discarded without regard to the test result. The analysis also highlights the social costs of excluding donors on the basis of ethnicity. The possibility of downstream HIV transmission from transfusion recipients infected from contaminated blood is also considered. All such calculations are made in a manner that deliberately favors the exclusion decision. In spite of such a one-sided analysis, the author concludes that the exclusion policy is not justifiable on cost-benefit grounds if the social costs of exclusion exceed $218,000 per year, or $3.63 per Ethiopian immigrant annually. Key words: public health; eco nomic analysis; policy; cost-benefit analysis; blood screening. (Med Decis Making 1999;19:207-213)
Correlations in Uncertainty Analysis for Medical Decision Making
Authors: Chessa Antonio G. , Dekker Rommert , Van Vliet Bas , Steyerberg Ewout W. , Habbema J. Dik F.
Published: March 2007

A Monte Carlo uncertainty analysis with correlations between parameters is applied to a Markov-chain model that is used to support the choice of a replacement heart-valve. The objective is to quantify the effects of uncertainty in and of correlations between probabilities of valve-related events on the life expectancies of four valve types. The uncertainty in the logit- and log-transformed parameters—mostly representing proba bilities and durations—is modeled as a multivariate normal distribution. The univariate distributions are obtained through values for the median and the 0.975 quantile of each parameter. Correlations between parameters are difficult to quantify. A sensitivity anal ysis is suggested to study their influences on the uncertainty in valve preference prior to further elicitation efforts. The results of the uncertainty analysis strengthen the con clusions from a preceding study, which did not include uncertainty in the model param eters, where the homograft turned out to be the best choice. It is concluded that the influence of correlations is limited in most cases. Preference statements become more certain when the correlation between valve types increases. Key words: uncertainty analysis; decision analysis; Monte Carlo simulation; Markov-chain; aortic valve. (Med Decis Making 1999; 19:276-286)
Screening Blood Donations for Hepatitis C in Central Africa
Authors: Cancré Nicole , Bois Frédéric , Grésenguet Gérard , Fretz Catherine , Fournel Jean-Jacques , Bélec Laurent
Published: March 2007

Four screening strategies (no testing, HC Abbott, HC Pasteur, and a combined test) for the detection of hepatitis C virus (HCV) antibody in donated blood were considered in a formal decision tree. Decision criteria included residual risk of infection and overall monetary cost. Tree parameters were determined using data from the Central African Republic. The prevalences observed among blood donors for HIV infection, hepatitis B, syphilis, and hepatitis C varied between 6% and 15%. The current residual risk of transfusion-transmitted infections is very high (8.4%). Screening for HCV would bring that risk down to about 3% with either the HC Pasteur, the HC Abbott, or the combined test. Even though baseline analysis gives preference to the HC Abbott test (the com bined test coming out last), Monte Carlo sensitivity and uncertainty analyses showed that Abbott's and Pasteur's tests are interchangeable, on the basis or either risk or cost considerations. Key words: Africa; blood donation; blood transfusion; decision tree analysis; hepatitis B virus; hepatitis C virus; human immunodeficiency virus; Monte Carlo; syphilis. (Med Decis Making 1999; 19:296-306)
Development of a Pediatric Multiple Organ Dysfunction Score
Authors: Leteurtre Stéphane , Martinot Alain , Duhamel Alain , Gauvin France , Grandbastien Bruno , Thi Vu Nam  , Proulx François , Lacroix Jacques , Leclerc Francis
Published: March 2007

Background. An organ dysfunction (OD) scoring system for critically ill children is not yet available, and the method for developing such a system is not well defined. The aim of this study was to compare two developmental methods for assessing OD in critically ill children. Methods. Consecutive admissions between January and May 1997 in three French and Canadian pediatric intensive care units (PICUs) were studied prospectively. Physiologic data were selected using a Delphi method; the most ab normal values during PICU stay were recorded. The outcome measure was the vital status at PICU discharge. Six organ systems were studied: hepatic, cardiovascular, renal, hematologic, respiratory, and neurologic. For each of the six organ systems, the PEdiatric Multiple OD (PEMOD) system included one variable and the PEdiatric Lo gistic OD (PELOD) system included several variables. Severity levels and relative weights of ODs were determined according to the mortality rate (PEMOD) or by logistic regression (PELOD). Results. There were 594 admissions, including 51 deaths (9%). Severity levels and relative weights of ODs were: four levels graded from 1 to 4 for the PEMOD system and three levels with scores of 1, 10, and 20 for PELOD system. For both systems, calibrations were good (p = 0.23 and p = 0.44 respectively). The PELOD system was more discriminant than the PEMOD system (areas under the ROC curves 0.98 and 0.92, respectively, p < 10 -5). Moreover, with the PEMOD system, four ODs did not contribute significantly to the prediction of PICU outcome. Conclusions. The PELOD system was more discriminant and had the advantage of taking into ac count both the relative severities among ODs and the degree of severity of each OD. Key words: intensive care unit; multiple organ failure; outcome measure; patient out come assessment; pediatric severity of illness index. (Med Decis Making 1999;19: 399-410)