bluuebunny/crossref_metadata_2025 huggingface dataset:
A Comprehensive League Table of Cost-Utility Ratios and a Sub-table of "Panel-worthy" Studies
Authors: Chapman Richard H. , Stone Patricia W. , Sandberg Eileen A. , Bell Chaim , Neumann Peter J.
Published: March 2007

Objectives. The authors compiled a comprehensive league table of cost/QALY ratios, and a standardized table of analyses satisfying selected Reference Case criteria from the USPHS Panel on Cost-Effectiveness in Health and Medicine. Methods. They identified 228 cost-utility analyses (CUAs) through literature searches, and abstracted data on methods and cost-utility ratios. The subset of "Panel-worthy" analyses used: a societal or broad health-care perspective, community or patient preference weights, net costs, incremental comparisons, and discounting of costs and QALYs. Results. The 228 CUAs included ratios for 647 interventions, ranging from cost-saving to $52,000,000/QALY (median = $12,000/QALY). The standardized table presents 112 ratios that met the "Panel-worthy" criteria, with articles published in recent years more likely to meet all of the criteria. Conclusions. The comprehensive league table (available on the Web) provides a useful reference, but ratios may not be comparable because of methodologic variations. The standardized table focuses on studies meeting basic methodologic criteria, potentially allowing for better comparison with future Reference Case analyses. Future studies should investigate the quality of analyses' underlying assumptions in addition to whether certain key procedural protocols were met. Key words: cost-utility analysis; league tables; economic evaluation. (Med Decis Making 2000;20:451-467)
Determining the Area under the ROC Curve for a Binary Diagnostic Test
Authors: Cantor Scott B. , Kattan Michael W.
Published: March 2007

The authors provide a simple calculation for the unbiased estimation of the area under the ROC curve for a binary diagnostic test or a continuously valued test result that is effectively used in a binary way. The formula described can be used to interpret the discriminative ability of a diagnostic test. Key words: ROC curve analysis, binary diagnostic test; discriminative ability. (Med Decis Making 2000;20:468-470)
Cancer Patients' Decision Making and Trial-entry Preferences
Authors: Llewellyn-Thomas Hilary A. , McGreal M. June , Thiel Elaine C.
Published: March 2007

The study purpose was to determine whether the framing of treatment information influenced patients' reported preferences for participating in treatment decision making and for trial entry. Ninety cancer patients read either neutrally-, positively-, or negatively-framed infor mation about a chemotherapeutic treatment, then indicated their preferences for participating in the treatment decision, and whether they would participate in a clinical trial incorporating this protocol. There was no difference across information groups in preferences for partici pating in treatment decision making or willingness to enter such a clinical trial. Preference for participation in treatment decision making was significantly related to age (t = 2.54; p = 0.022), sex (x2 = 3.89; p = 0.05), and education (t = 2.54; p = 0.018); trial entry preferences were unrelated to these demographic variables. These results imply that, in this clinical context, attitudes towards participation in treatment decision making may be asso ciated with characteristics of the patient, and attitudes towards trial entry may be dependent upon the clinical characteristics of a particular trial, but neither set of attitudes is influenced by the framing of protocol information. Key words: framing effect; patients' preferences; quality of life; decision making; clinical trials. (Med Decis Making 1995;15:4-12)
Time in Health
Authors: Gafni Amiram
Published: March 2007

The time dimension in health is assessed and/or explained using the concept of time pref erence, i.e., preferences about when things occur or the timing of an outcome. It is believed that an individual's time preference can be relatively easily measured. This paper argues that individuals' responses to time-preference-type questions may represent not only their attitudes toward the timing of events (i.e., the points in time at which they are going to occur) but also their attitudes toward other things, such as the sequence of events (i.e., the order of good and bad events over an individual's lifetime health profile). This paper explains the distinction between the time-preference and sequence-preference concepts. Using two re cent empirical studies, it demonstrates the inability to measure individuals' pure time pref erences. The implications of this empirical obstacle in the context of medical decision making and health-care program evaluation are discussed. Key words: time preference; discounting; discounted utility model. (Med Decis Making 1995;15:31-37)
Meta-analytic Tools for Medical Decision Making: A Practical Guide
Authors: Hasselblad Vic , McCrory Douglas C.
Published: March 2007

This paper is an extension of notes used for the short course in meta-analysis given at the 13th and 14th annual meetings of the Society for Medical Decision Making. The material covers both standard and evolving methods of meta-analysis. The methods include those for combining p-values, for analyzing general fixed-effects models, for analyzing contingency tables, and for analyzing count and continuous outcomes. For each general method, the authors present simplified formulas first, followed by more precise formulas when necessary. Similarly, both classic and Bayesian methods are presented where appropriate. Actual ex amples are used for methods. Key words: meta-analysis; Bayesian methods; information synthesis. (Med Decis Making 1995;15:81-96)
Optimal Interval for Triple-lumen Catheter Changes
Authors: Ritchey Nathan P. , Caccamo Leonard P. , Carter Kimbroe J. , Castro Frank , Erickson Barbara A. , Johnson William , Kessler Edward , Ruiz Claudio A.
Published: March 2007

A survey of 53 university and community hospitals revealed that 73% of the institutions had no standard policy for the replacement of triple-lumen catheters (TLCs). Since the mainte nance of a TLC in place for a prolonged period may lead to infectious complications, it appeared warranted that standards of management be developed. A decision-tree model was constructed for evaluating the optimal time for changing a TLC that would minimize infection. Cost estimates and health effects at three-, five-, and ten-day change intervals were considered for catheter insertion and complications resulting from such insertion. The results suggested that prophylactic catheter changes should occur no later than every five days, provided that there are no signs of infection. However, sensitivity analysis of several variables suggested that individual institutions should establish policy timing changes based upon careful interpretation of their own data. A model was developed to assist in determining the optimal time to change a TLC based upon such data. Key words: triple-lumen catheter; catheter-related infection; sepsis; decision analysis. (Med Decis Making 1995;15:138-142)
Advance Directives
Authors: Raymark Patrick H. , Balzer William K. , Doherty Michael E. , Warren Karen , Meeske Jessica , Tape Thomas G. , Wigton Robert S.
Published: March 2007

Policy capturing was used to provide insight into those factors that people consider important in the decision of whether to accept life-sustaining medical treatment. First, open-ended interviews with community-dwelling elderly persons ( n = 30) were conducted to determine the factors they would consider when drafting an advance directive. College students ( n = 53) then made judgments as to whether they would accept life-sustaining treatment for each of 100 hypothetical vignettes comprising a similar set of factors. Results revealed that 1) students made consistent judgments, 2) there was considerable variability in their mean judgments, 3) the most influential factors were mental and physical functioning, 4) mental and physical functioning had an interactive effect on judgments, and 5) subjective estimates of importance were significantly related to policy-capturing weights. This approach for study ing the relationship of individuals' values to their acceptance of life-sustaining therapy may be useful in future studies of patient and surrogate decision making. Key words: advance directives; decision making; judgment. (Med Decis Making 1995;15:217-226)
Probability Judgment in Medicine
Authors: Redelmeier Donald A. , Koehler Derek J. , Liberman Varda , Tversky Amos
Published: March 2007

Research in cognitive psychology has indicated that alternative descriptions of the same event can give rise to different probability judgments. This observation has led to the de velopment of a descriptive account, called support theory, which assumes that the judged probability of an explicit description of an event (that lists specific possibilities) generally exceeds the judged probability of an implicit description of the same event (that does not mention specific possibilities). To investigate this assumption in medical judgment, the au thors presented physicians with brief clinical scenarios describing individual patients and elicited diagnostic and prognostic probability judgments. The results showed that the phy sicians tended to discount unspecified possibilities, as predicted by support theory. The authors suggest that an awareness of the discrepancy between intuitive judgments and the laws of chance may provide opportunities for improving medical decision making. Key words: probability judgment; support theory; unpacking principle; cognition. (Med Decis Making 1995;15:227-230)
Effects of Patient Education on Decisions about Breast Cancer Treatments
Authors: Chapman Gretchen B. , Elstein Arthur S. , Hughes Katharine Kostbade
Published: March 2007

The authors examined the effects of materials for educating patients about treatment options for breast cancer on knowledge about the disease, preferences for alternative treatments, and how changes in knowledge and preferences were related. Eighty-two undergraduate students acted as advisors to a hypothetical patient. They completed a knowledge test and rated their preferences for three options-breast-sparing surgery with radiation, mastectomy followed by reconstructive surgery, and mastectomy followed by use of a breast prosthesis— before and after viewing a videotape or a booklet version of the educational materials. Both formats increased knowledge scores. Treatment preferences were not affected by reading the booklet, but viewing the videotape resulted in a preference shift toward breast-sparing surgery. This media difference may be due to features of the video that were not reproduced in the booklet, such as interviews with other patients. Knowledge gains were uncorrelated with preference changes. Key words: patient decision making; patient education; breast cancer; educational technology; video; knowledge; preferences. (Med Decis Making 1995;15:231-239)
Proportional Heuristics in Time Tradeoff and Conjoint Measurement
Authors: Stalmeier Peep F.M. , Bezembinder Thom G.G. , Unic Ivana J.
Published: March 2007

The time-tradeoff (TTO) test is widely used to measure quality of life for different health states. Subjects are asked to equate the value of living a given period in an inferior health state to the value of living a shorter period in good health. Applications of TTOs have been criticized based on the fact that the value of future life duration is taken as the future life duration itself. The authors show that for a health state in which a subject does not want to live longer than a specified amount of time, subjects' responses do not comply with the assumption that the value of the period in inferior health is equated to the value of the shorter period in good health Actually, preference reversals with respect to such a health state point to the use of a proportional heuristic in the TTO test. Comparisons of the TTO test in these subjects with category scaling and difference measurements also favor a proportional inter pretation of the TTO test. In tests based on conjoint measurement, these subjects also appear to use a proportional heuristic. Consequences of the use of the TTO test and conjoint measurement m quality-of-life models are discussed Key words: utility assessment, QALY, conjoint measurement; preference reversals; compatibility effect. (Med Decis Making 1996;16:36-44)
Modeling Boolean Decision Rules Applied to Multiple-observer Decision Strategies
Authors: Maguire William
Published: March 2007

A model that derives multiple-observer decision strategy ROC curves for boolean decision rules applied to binary decisions of two or three observers is presented. It is assumed that covert decision variables consistent with ROC models of observer performance underlie decisions and that readers' decision criteria are in a fixed relationship. The specific param eters of individual ROC curves and the correlational structure that describes interobserver agreement have dramatic effects upon the relative benefits to be derived from different boolean strategies A common strategy employed in clinical practice, in which the overall decision is positive if any observer makes a positive decision, is most effective when the readers are of similar ability, when they adopt similar decision criteria, when interreader agreement is greater for negative than for positive cases, and when the individual ROC slope is «1.0 Different multiple-observer decision strategies can be evaluated using the model equations A bootstrap method for testing model-associated hypotheses is described. Key words: ROC analysis; diagnostic accuracy; image interpretation. (Med Decis Making 1996;16:51-57)
On the Equivalence of Collectively and Individually Collected Responses
Authors: Krabbe Paul F.M. , Essink-Bot Marie-Louise , Bonsel Gouke J.
Published: March 2007

The standard-gamble and time-tradeoff methods for valuing health states were com pared in a multifactorial design with 104 student volunteers. The main aim of the ex periment was to compare average individual responses with group responses for the same tradeoff tasks. Group responses were collected using an interactive voting sys tem. The standard EuroQol system was used to describe the health states to be val ued. Generalizability theory was used to analyze the results. The averages and median values of the individual responses differed from the interactively collected group values only for the more severe health states. The results showed almost identical results for the two methods, but the time tradeoff was found to be more consistent than the standard gamble. The authors conclude that 1) there is significant similarity between the results of individual and collective response modes, and 2) the standard-gamble and time-tradeoff methods produce almost equivalent values, despite their different conceptual backgrounds. In this study the aggregated individual responses and the collective response proved to be sufficiently similar to support the validity of using aggregated individual valuations as a measure of the valuation of the group. Key words: collective judgment; standard gamble; time tradeoff; methodology; voting sys tem ; EuroQol; generalizability theory. (Med Decis Making 1996;16:120-132)
The Effect of Disease-prevalence Adjustments on the Accuracy of a Logistic Prediction Model
Authors: Morise Anthony P. , Diamond George A. , Detrano Robert , Bobbio Marco , Gunel Erdogan
Published: March 2007

The accuracy of a logistic prediction model is degraded when it is transported to pop ulations with outcome prevalences different from that of the population used to derive the model. The resultant errors can have major clinical implications. Accordingly, the authors developed a logistic prediction model with respect to the noninvasive diagnosis of coronary disease based on 1,824 patients who underwent exercise testing and coronary angiography, varied the prevalence of disease in various "test" populations by random sampling of the original "derivation" population, and determined the accu racy of the logistic prediction model before and after the application of a mathematical algorithm designed to adjust only for these differences in prevalence. The accuracy of each prediction model was quantified in terms of receiver operating characteristic (ROC) curve area (discrimination) and chi-square goodness-of-fit (calibration). As the prevalence of the test population diverged from the prevalence of the derivation pop ulation, discrimination improved (ROC-curve areas increased from 0.82 ± 0.02 to 0.87 ± 0.03; p < 0.05), and calibration deteriorated (chi-square goodness-of-fit statistics increased from 9 to 154; p < 0.05). Following adjustment of the logistic intercept for differences in prevalence, discrimination was unchanged and calibration improved (maximum chi-square goodness-of-fit fell from 154 to 16). When the adjusted algorithm was applied to three geographically remote populations with prevalences that differed from that of the derivation population, calibration improved 87%, while discrimination fell by 1 %. Thus, prevalence differences produce statistically significant and potentially clinically important errors in the accuracy of logistic prediction models. These errors can potentially be mitigated by use of a relatively simple mathematical correction al gorithm. Key words: logistic prediction model; accuracy; prevalence adjustments; model transportability. (Med Decis Making 1996;16:133-142)
Public Perceptions of the Importance of Prognosis in Allocating Transplantable Livers to Children
Authors: Ubel Peter A. , Loewenstein George
Published: March 2007

Background. The system to allocate scarce transplantable livers has been criticized for not giving enough weight to the prognoses of the patients receiving the transplants, but little research has been done looking at how the public weights the relative impor tances of efficacy and equity in distributing the organs. Methods. This study was an experimental survey of prospective jurors asked to distribute transplantable livers among transplant candidates grouped according to their prognoses. The relative prog noses of the transplant candidates were varied across survey versions. Results. As the prognostic difference between transplant groups increased, the subjects became less likely to distribute the organs equally between them (p < 0.005). However, the subjects' willingness to base allocation on prognosis was moderated by a number of factors, including their understanding of how to use prognostic information and their attitudes toward using prognostic information for individuals versus groups. Thus, even when the relative prognoses of transplant groups differed by 60%, less than a fourth of the subjects were willing to give all the organs to the better-prognosis group. Con clusion. Many subjects feel that prognosis is an important consideration in allocating scarce livers. However, few are willing to base allocation purely on maximizing survival. Policies that base allocations purely on outcomes will violate the values of a significant portion of the public. Key words: transplantation; equity; prognosis; ethics; health pol icy. (Med Decis Making 1996;16:234-241)
Comparing Three Versions of the Time Tradeoff
Authors: Kenneth Buckingham J. , Birdsall Jennifer , Douglas John Graham
Published: March 2007

This paper reports a comparative study of three formulations of the time-tradeoff (TTO) method of health valuation. One asks people to consider giving up time each day in exchange for better health. The second asks people to consider giving up time during a 12-month interval. The third is the more conventional TTO in which people are asked to contemplate a reduction in life expectancy. Questionnaires were sent to 4,087 adults selected at random from the population of Scotland. Each respondent provided a de scription of his or her health, and was asked to value an improvement in that health, using all three formulations of the TTO. The daily TTO appeared to be an improvement on the conventional formulation, correlating more strongly with health, eliciting re sponses that appeared to be more precise, and obtaining information about the value of health from a far greater number of respondents. The performance of the annual TTO appeared to be only slightly inferior to that of the daily TTO. Key words: time tradeoff; quality of life; health valuation. (Med Decis Making 1996;16:335-347)
Bayesian Analysis of ROC Curves Using Markov-chain Monte Carlo Methods
Authors: Fengchun Peng  , Hall W.Jack
Published: March 2007

The authors introduce a Bayesian approach to generalized linear regression models for rating data observed in the evaluation of a diagnostic technology. Such models were previously studied using a non-Bayesian approach. In a Bayesian analysis, the difficulties inherent in an ordinal rating scale are circumvented by using data-augmen tation techniques. Posterior distributions for the regression parameters—and thereby for receiver operating charactenstic (ROC) curve parameters and values, for the area under a ROC curve, differences between areas, etc.—may then be computed by Mar kov-chain Monte Carlo methods. Inferences are made in standard Bayesian ways. The methods are exemplified by a study of ultrasonography rating data for the detection of hepatic metastases in patients with colon or breast cancer (previously analyzed) and the results compared. Key words: diagnostic test; ordinal regression; sensitivity; spec ificity. (Med Decis Making 1996;16:404-411)
The Influences of Patient Characteristics and Physician Experience on Case Recall
Authors: Durante Richard , McKinlay John B. , Kasten Linda , Potter Deborah A.
Published: March 2007

The study focused on the influences of both patient characteristics and physician experience on the recall of two breast cancer cases. Two general research questions were addressed: 1) whether patient characteristics such as age, race, and assertive-ness affect a physician's initial problem representation, and 2) whether the recall advantage for physicians of intermediate levels of experience extends to physicians who have been out of medical school for at least six years. 128 physicians with a minimum of six years' experience were presented with two videotapes of a doctor-patient encounter. In the first videotape (the pre-workup scenario), the patient had just discovered a lump; in the second (the post-workup scenario), she had recently had a biopsy. Following the presentation of each videotape, the physicians were instructed to record a synopsis of the case prior to making diagnoses, ordering tests, and providing treatment recommendations. The synopses were coded to capture information from the cases that the physicians were able to recall and inferences that they generated based on this information. Two critical findings were obtained. First, none of the patient characteristics investigated consistently produced differences in recall or inference generation across the two scenarios. Second, physician recall was a monotonically decreasing function of years of experience. The latter result is interpreted using a theoretical framework from Schmidt and Boshuizen. Key words: cognition; memory; recall; breast cancer; physicians; decision making; problem solving. (Med Decis Making 1997;17: 199-207)
Representation and Analysis of Medical Decision Problems with Influence Diagrams
Authors: Owens Douglas K. , Shachter Ross D. , Nease Robert F.
Published: March 2007

Influence diagrams are a powerful graphic representation for decision models, complementary to decision trees. Influence diagrams and decision trees are different graphic representations for the same underlying mathematical model and operations. This article describes the elements of an influence diagram, and shows several familiar decision problems represented as decision trees and as influence diagrams. The authors also contrast the information highlighted in each graphic representation, demonstrate how to calculate the expected utilities of decision alternatives modeled with an influence diagram, provide an overview of the conceptual basis of the solution algorithms that have been developed for influence diagrams, discuss the strengths and limitations of influence diagrams relative to decision trees, and describe the mathematical operations that are used to evaluate both decision trees and influence diagrams. They use clinical examples to illustrate the mathematical operations of the influence-diagram-evaluation algorithm; these operations are arc reversal, chance node removal by averaging, and decision node removal by policy determination. Influence diagrams may be helpful when problems have a high degree of conditional independence, when large models are needed, when communication of the probabilistic relationships is important, or when the analysis requires extensive Bayesian updating. The choice of graphic representation should be governed by convenience, and will depend on the problem being analyzed, on the experience of the analyst, and on the background of the consumers of the analysis. Key words: decision analysis; influence diagrams; cost-effectiveness analysis; Bayesian updating; graphic representation. (Med Decis Making 1997;17:241-262)
Patient Participation in Deciding Breast Cancer Treatment and Subsequent Quality of Life
Authors: Street Richard L. , Voigt Becky
Published: March 2007

This investigation of patients with early breast cancer examined relationships among patient involvement in deciding treatment (i.e., whether to undergo breast removal or breast conservation), perceptions of control over treatment decisions, and subsequent health-related quality of life. It was predicted 1) that patients who more actively participated in consultations to decide treatment would perceive more decision control than would more passive patients and 2) that patients who perceived greater decision control would report better health-related quality of life following treatment than would patients perceiving less decision control. Sixty patients with stage I or II breast cancer allowed their consultations with surgeons to be audiorecorded. Following these visits, patients reported on their involvement in the consultation, optimism for the future, knowledge about treatment, and two aspects of perceived decision control, the perception of having a choice for treatment and the extent to which the doctor or patient was responsible for the decision. Six and 12 months postoperatively, 51 patients (85%) returned a follow-up survey assessing perceived decision control and health-related quality of life. The first prediction received some support. The patients who had more actively participated in their consultations, particularly in terms of offering opinions, assumed more responsibility for treatment decisions during the year following surgery than did less expressive patients. Also, the patients who reported more involvement in their consultations later believed they had had more of a choice for treatment. The second hypothesis was partially supported. Six and 12 months following treatment, the patients who believed they were more responsible for treatment decisions and believed they had more choice of treatment reported higher levels of quality of life than did the patients who perceived themselves to have less decision control. However, perceived control at the time of treatment did not predict later quality of life. Theoretical and clinical implications are discussed. Key words : decision control; patient participation; breast cancer; health-related quality of life. (Med Decis Making 1997;17:298-306)
Community-based Research—A Framework for Problem Formulation:
Authors: Helfand Mark , Oehlke Megan A. , Lieberman David A.
Published: March 2007

Objective. To identify clinical hypotheses and information gaps underlying disagreement about the use of upper gastrointestinal endoscopy (EGD) for the diagnosis of gastroesophageal reflux disease (GERD), and to design a registry study to test these hypotheses. Design and setting. Structured group discussions with community-based practicing gastroenterologists. Results. Thirty-three gastroenterologists from 17 sites discussed a set of clinical scenarios concerning the use of EGD in GERD patients with different clinical histories. Clinicians identified patient characteristics and outcome variables missing from the original problem formulation. Using decision tables, the combinations of patient characteristics that provoked disagreement among clinicians were determined. The resulting decision tables specified which characteristics and outcome variables should be measured to test competing clinical theories of when to use EGD in patients with GERD. Subsequently, the clinicians conducted a practice-based study measuring uncertain variables associated with disagreement about the need for EGD in specific clinical situations. Conclusion. A structured, but flexible, approach to group discussion may help identify factors that are important in decision making and the hypotheses that should be addressed in resolving variations in practice styles. Technology assessors can use these methods to identify variables underlying clinicians' concerns about the clinical validity of recommendations about practice. This experience with eliciting patient characteristics and uncertain variables underscores the importance of involving practicing clinicians in the process and could be a useful model for problem formulation in guideline development and in community-based research. Key words: decision-support techniques; physician practice patterns; gastroesophageal reflux ; endoscopy; gastrointestinal; practice guidelines. (Med Decis Making 1997;17: 315-323)
The Cost-Effectiveness of Fluconazole Prophylaxis against Primary Systemic Fungal Infections in AIDS Patients
Authors: Scharfstein Julie A. , Paltiel A. David , Freedberg Kenneth A.
Published: March 2007

Objective. To project the cost-effectiveness of fluconazole for prophylaxis against AIDS-related primary systemic fungal infections. Design. A Markov model with data from the literature. Patients. Hypothetical cohort of 100,000 AIDS patients. Intervention. No prophylaxis, and fluconazole prophylaxis beginning when a patient's CD4 count declined to below 200/mm3, below 100/mm 3, or below 50/mm3. Results. The no-pro phylaxis policy was associated with a discounted life expectancy of 28.20 months and direct medical costs of $36,100 per person. The <200/mm3 strategy increased costs to $40,500 and life expectancy to 28.42 months, producing a ratio of $240,000 per year of life saved (YLS). Compared with the no-prophylaxis and <200/mm3 policies, the intermediate alternatives were less economically efficient. A reduction in flucona zole's cost from $206 to $80 decreased the ratio to $50,000 for the <200/mm3 strategy. Doubling fungal infection incidence lowered this ratio to $96,000/YLS. Conclusions. Fluconazole prophylaxis is unlikely to be cost-effective unless its cost is lowered, or it is focused on patients in regions endemic for fungal infections. Key words: fluconazole; prophylaxis; AIDS; cost-effectiveness; Markov model. (Med Decis Making 1997;17: 373-381)
Incorporating Future Costs in Medical Cost-Effectiveness Analysis
Authors: Johannesson Magnus , Meltzer David , O'Conor Richard M.
Published: March 2007

It has been shown that the difference between consumption and production during life years gained should be included as a cost in cost-effectiveness analysis. In this study the authors estimate the impact of including these future costs on the cost-effective ness of the treatment of hypertension in Sweden. The cost per quality-adjusted life year (QALY) gained changes little among young men and women due to the addition of future costs, but increases by about $14,000 for middle-aged men and women and about $27,000 for older men and women. When future costs are not included, the cost per QALY gained is generally lowest among older men and women, but when future costs are included, the cost per QALY gained is generally lowest among middle-aged men and women. The authors conclude that the total resource consequences of changes in mortality should be routinely considered in cost-effectiveness analyses. Key words: Cost-effectiveness analysis; economic evaluation; costs; societal per spective. (Med Decis Making 1997;17:382-389)
Are Methods for Estimating QALYs in Cost-Effectiveness Analyses Improving?
Authors: Neumann Peter J. , Zinner Darren E. , Wright Janice C.
Published: March 2007

Objectives. The objectives of this study were to examine variations in the methods used by researchers to estimate QALYs in published cost-effectiveness analyses, and to investigate whether the methods have improved over time. Data and methods. Using a MEDLINE search, the authors identified 86 original cost-effectiveness analyses, pub lished between 1975 and 1995, that used QALYs as the measure of effectiveness. For each study, they recorded the health-state classification system, the source of the preference weights, the measurement technique, and the discount rate. The methods used were compared with the recommendations of the U.S. Panel on Cost-Effective ness in Health and Medicine. Results. Only 20% of the studies used "generic" health- state classification systems (e.g., health utilities index); 21% relied on community- based weights; 40% used formal measurement techniques (e.g., time-tradeoff method); and 88% discounted both future costs and QALYs. There was little evidence that methods had improved over time. Conclusions. The results illustrate extensive variation in the construction of QALYs in cost-effectiveness analyses and reveal that most studies have not adhered to practices now recommended by leaders in the field. There is a need for more methodologic rigor and consistency if the results of such studies are to be compared and used for purposes of allocating resources. Key words: QALYs; quality-adjusted; cost-effectiveness analysis. (Med Decis Making 1997;17: 402-408)
Whose Blood Is Safer?
Authors: Litvak Eugene , Siegel Joanna E. , Pauker Stephen G. , Lallemant Marc , Fineberg Harvey V. , Weinstein Milton C.
Published: March 2007

Background. With improvements in HIV antibody test (ELISA) performance, the win dow of time between infection and seroconversion becomes a major source of error in HIV screening. The authors examined its impact on the false-reassurance rate (FRR). Methods. Test sensitivity was modeled as the product of two factors: the in herent sensitivity (sensitivity when antibody is present) and the probability that antibody is present in infected blood. A model of HIV and AIDS incidence was used to derive an estimate of the probability of remaining in the seronegative window ( pw) among those who are infected. With plausible assumptions, this probability approaches 0.03. The FRR was then estimated as a function of the probability of remaining in the se ronegative window, the prevalence of HIV, and the inherent sensitivity of the ELISA test were estimated. Results. The FRRs for two blood donor groups, one with an HIV prevalence of 0.004 and a typical probability of remaining in the seronegative window ( pw = 0.03) and the other with a higher prevalence of 0.017 but fewer donors in the window ( pw = 0.003), are equal (140 per million donors) if the blood is negative on a single ELISA test. After two negative tests or a single test that can detect antibody more reliably, however, the FRR is much higher in the group with the higher pw (= 120 per million compared with 50 per million), because the greater numbers of donors in the window more than offsets the lower prevalence. Conclusions. With improvements in inherent sensitivity of ELISA by virtue of technical progress or retesting, the preva lence of HIV infection may no longer play the critical role in degrading the results of blood screening. As inherent test performance improves, tests are increasingly likely to miss infected blood because of the seronegative-window error rather than because of measurement error. Window error plays a proportionally greater role during the early stages of HIV dissemination in a population where the incidence of new HIV infection is high relative to the incidence of AIDS. These findings may explain, in part, the recent observation that cases of transfusion of contaminated blood often take place in areas where AIDS epidemics have started recently. They also suggest that the traditional strategy of soliciting blood donors from low-prevalence populations may not always be optimal, unless such populations are truly low-risk. Key words: HIV; AIDS; prevalence; incidence; sensitivity; ELISA; predicted values; protocols of screening; false-reassur ance rate. (Med Decis Making 1997;17:455-463)
Meta-analysis of Multitreatment Studies
Authors: Hasselblad Vic
Published: March 2007

Studies comparing more than two competing therapies are common in several fields, but standard meta-analytic methods can make only pairwise comparisons. The meth ods proposed in this article, a generalization of current meta-analytic methods, allow for any number of competing therapies and include both fixed- and random-effects models. Key words: meta-analysis; random-effects models; multiple treatment studies. (Med Decis Making 1998;18:37-43)
Neural Network Assessment of Perioperative Cardiac Risk in Vascular Surgery Patients
Authors: Lapuerta Pablo , L'Italien Gilbert J. , Paul Sumita , Hendel Robert C. , Leppo Jeffrey A. , Fleisher Lee A. , Cohen Mylan C. , Eagle Kim A. , Giugliano Robert P.
Published: March 2007

Neural networks were developed to predict perioperative cardiac complications with data from 567 vascular surgery patients. Neural network scores were based on cardiac risk factors and dipyridamole thallium results. These scores were converted into like lihood ratios that predicted cardiac risk. The prognostic accuracy of the neural networks was similar to that of logistic regression models (ROC areas 76.0% vs 75.8%), but their calibration was better. Logistic regression overestimated event rates in a group of high-risk patients (predicted event rate, 64%; observed rate 30%; n = 50, p < 0.001). On a validation set of 514 patients, the neural networks still had ROC similar areas to those of logistic regression (68.3% vs 67.5%), but logistic regression again overesti mated event rates for a group of high-risk patients. The calibration difference was reflected in the Hosmer-Lemeshow chi-square statistic (18.6 for the neural networks, 45.0 for logistic regression). The neural networks successfully estimated perioperative cardiac risk with better calibration than comparable logistic regression models. Key words. neural networks; logistic regression; likelihood ratio; Bayes' theorem; cardiac risk. (Med Decis Making 1998;18:70-75)
The Effect of Search Procedures on Utility Elicitations
Authors: Lenert Leslie A. , Cher Daniel J. , Goldstein Mary K. , Bergen Merlynn R. , Garber Alan
Published: March 2007

Objective. Elicited preferences for health states vary among scaling methods, manners of describing health states, and other features of the elicitation process. The authors examined the effects of changing the search procedure for a subject's utility on mean utility values. Methods. A randomized controlled trial of two search procedures (titration and "ping-pong") using two otherwise identical computer programs that describe health states related to Gaucher's disease, then measuring subjects' preferences. Setting. Paid, healthy volunteers recruited from the community through advertisements. Re sults. The mean time tradeoff (TTO) and standard gamble (SG) utility values for life with severe anemia and splenomegaly and life with chronic bone pain from Gaucher's disease were between 0.10 and 0.15 higher with the titration search procedure than with the ping-pong procedure. Effects of the search procedure were additive with var iability due to scaling methods, resulting in mean differences in utility ratings for the same health state of as much as 0.28 among procedures and scaling methods. Effects of search procedures on utility values persisted on repeated testing at week 2 and week 3; there was no evidence of convergence to a single "true" utility value over time. Conclusions. The procedure used to search for subjects' utility values strongly influences the results of preference-assessment experiments. Effects of search pro cedures persist on repeated testing. The results suggest that utility values are heavily influenced by, if not created during, the process of elicitation. Thus, utility values elic ited using different search procedures may not be directly comparable. Key words: search procedures; utility elicitations; patient preferences; titration; ping-pong. (Med Decis Making 1998;18:76-83)
Treatment Choices by Seriously III Patients
Authors: Gaskin Darrell J. , Kong Janet , Meropol Neal J. , Yabroff K. Robin , Weaver Charles , Schulman Kevin A.
Published: March 2007

Anecdotal evidence suggests that patients who have life-threatening conditions often choose to undergo high-cost, high-risk treatments for them. This kind of risk-seeking behavior seems irrational because most patients are risk-averse. The Health Stock Risk Adjustment (HSRA) model seeks to explain this phenomenon. The model is based on the concept of relative health stock—the ratio of patients' expected quality-adjusted life years (QALYs) after a diagnosis to their expected QALYs before the diagnosis. The model predicts risk-averse patients will behave in a risk-seeking manner as their relative health stocks deteriorate. The HSRA model can help physicians better under stand why some seriously ill patients seek high-risk treatments while others elect to forgo treatment. State legislatures and insurers are attempting to appropriately design insurance benefits for patients with life-threatening conditions. The HSRA model can help predict which patients will most likely take advantage of these benefits. Key words: patients' preferences; decision making; expected utility theory; treatment choice. (Med Decis Making 1998;18:84-94)
The Role of Clinical “Experience” in Diagnostic Performance
Authors: Fasoli Angelo , Lucchelli Silvia , Fasoli Renato
Published: March 2007

Twenty-one physicians examined records of 43 patients who had attended the hospital because of chest pain. Of these patients, 20 had had coronary heart disease (CHD), 15 had had nonspecific pain, and eight had had pulmonary embolism. The physicians indicated the probability of CHD in each case on the basis of 18 clinical findings, not including ECG, x-ray, or biochemical studies. The trial was repeated five years later, using the same records, by 16 of the same physicians. Diagnostic accuracy was evaluated by ROC curves, and the weight ascribed to each cue was inferred by multiple regression with estimated probability of CHD as the dependent variable. No significant change of areas under the ROC curves with increasing length of clinical experience was observed. Multiple regression was significant in 30 of 37 analyses. The distributions of most physicians' estimates of probabilities had similar shapes five years apart. It is concluded that “experience” does not have a clear role in diagnostic performance based on recorded data and that personal calibration and preferences in estimating probabilities often persist for years.
Treatment of Early-Stage Breast Cancer in the Elderly
Authors: Carter Kimbroe J. , Ritchey Nathan P. , Castro Frank , Caccamo Leonard P. , Kessler Edward , Erickson Barbara A. , Gawdyda Lori M.
Published: March 2007

Purpose. To evaluate the post-lumpectomy treatment of a nonpalpable, stage I, T1b tumor, mammographically detected, in a 74-year-old woman without comorbidities. Methods. A Markov process, through 120 monthly cycles, was used to model patient progression through a treatment program, employing literature data and a health-outcome utility. Treatments considered were: observation; radiation totaling 5,000 cGy over six weeks; tamoxifen, 20 mg/day, for five years; simple mastectomy; and radiation therapy plus tamoxifen. Health states included absence of disease (NED), loco-regional recurrence, distant metastasis, age-sex-race (ASR)-adjusted death, cancer mortality, treatment complications, and post-mastectomy death. Transition probabilities were established from the literature. Health-state utilities were determined from the responses of health care professionals to a basic reference gamble. Results. Quality-adjusted life years (QALYs) were determined to be 8.19 for radiation plus tamoxifen, decreasing to 8.04 for mastectomy, a difference of only a 0.15 years (1.8 months). Sensitivity analysis, however, showed relative stability in the ranking among treatment options. Conclusion. Although the model showed little difference between QALYs with the treatments, the combination of radiation and tamoxifen provides the optimal therapy for this case.
Perfect Timing, No Remorse, and Kidney Transplantation
Authors: Brand Donald A.
Published: March 2007

Kidney transplantation is usually delayed until a patient has reached end-stage renal failure. When a living donor is used, earlier transplantation may be feasible. By averting the final stages of renal failure, early transplantation spares the patient the more pronounced effects of uremia. Unfortunately, lack of precision in predicting the future course of a patient's disease creates a dilemma: the kidneys could remain viable longer than anticipated. In that case, an early transplantation that leads to serious complications or graft failure will have caused harm by truncating the period of time the patient could have been sustained by his or her native kidneys. The present article introduces a theorem that helps solve the dilemma of early kidney transplantation. The theorem states that the timing decision depends only on the current burden of a disease relative to the nsks of transplantation—that the future rate of progression of the disease is immaterial. The generality of the theorem makes it applicable, in principle, to any de generative disease that can be treated by engraftment. The article also introduces a formula for the optimal timing of transplantation that depends on only four factors-a patient's perceived quality of life before transplantation as a function of time, the mortality associated with a transplant operation, the graft survival curve, and the quality of life in the event of a graft failure. The theorem and related formula should be helpful to patients and physicians in selecting the best time for transplantation. Key words: kidney transplantation; decision theory; decision support; quality of life. (Med Decis Making 1998;18:249-255)
Prostate Cancer Patients' Utilities for Health States
Authors: Chapman Gretchen B. , Elstein Arthur S. , Kuzel Timothy M. , Sharifi Roohollah , Nadler Robert B. , Andrews Anita , Bennett Charles L.
Published: March 2007

Two versions of the time-tradeoff (TTO) method were compared. In the personal TTO version, 31 prostate cancer patients decided whether they personally would give up some longevity to have perfect health rather than a longer life in a state of poor health associated with prostate cancer. In the impersonal version, 28 patients compared two hypothetical friends, one of whom has perfect health but will live less time than the other who is in poor health, and decided which person they would rather be. All patients evaluated three hypothetical health states. The two TTO methods were assessed by examining 1) how well they distinguished three health states of varying degrees of dysfunction and 2) patients' willingness to trade time for quality of life. Patients using the impersonal TTO version were more likely than those using the personal version to order the three health states appropriately (68% vs 16%, p < 0.0001) and were more willing to trade off length of life for quality of life (p < 0.05). Key words: decision making; patient participation; decision theory; prostatic neoplasms. (Med Decis Making 1998; 18:278-286)