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D A Redelmeier

Publications and source records attributed to D A Redelmeier.

86 records · Page 5Linked to original sources
PubMedDate not supplied

The beguiling pursuit of more information.

BACKGROUND: The authors tested whether clinicians make different decisions if they pursue information than if they receive the same information from the start. METHODS: Three groups of clinicians participated (N=1206): dialysis nurses (n=171), practicing urologists (n=461), and academic physicians (n=574). Surveys were sent to each group containing medical scenarios formulated in 1 of 2 versions. The simple version of each scenario presented a choice between 2 options. The search version presented the same choice but only after some information had been missing and subsequently obtained. The 2 versions otherwise contained identical data and were randomly assigned. RESULTS: In one scenario involving a personal choice about kidney donation, more dialysis nurses were willing to donate when they first decided to be tested for compatibility and were found suitable than when theyknew they were suitable from the start (65% vs. 44%, P= 0.007). Similar discrepancies were found in decisions made by practicing urologists concerning surgery for a patient with prostate cancer and in decisions of academic physicians considering emergency management for a patient with acute chest pain. CONCLUSIONS: The pursuit of information can increase its salience and cause clinicians to assign more importance to the information than if the same information was immediately available. An awareness of this cognitive bias may lead to improved decision making in difficult medical situations.

Canada↗
PubMedDate not supplied

Time preference in medical decision making and cost-effectiveness analysis.

Cost-effectiveness analyses usually quantify peoples' attitudes towards delayed outcomes using the exponential discount model. The authors examined three assumptions of this model by assessing the time preferences of individuals towards hypothetical health states and calculating implicit annual discount rates. Of a random sample of medical students, house officers, and attending physicians, 121 participated, reflecting a response rate of 81%. The participants considered three temporary events (colostomy, blindness, depression) that were destined to occur at five sequentially distant times in the future (one day, six months, one year, five years, and ten years). The utility of each prospect was measured using two elicitation techniques (standard gamble and categorical scaling), and 1,394 implicit discount rates were calculated. Of all the discount rates, 62.1% equalled zero, 10.0% were less than 0.00, and 15.7% were greater than 0.10. Mean discount rates for relatively proximal time intervals tended to be larger than those for relatively more distant intervals (0.041 vs. 0.025, p < 0.01). Mean discount rates for blindness tended to be smaller than those for colostomy or depression (0.023 vs. 0.039 vs 0.037, respectively, p < 0.005). Hence, peoples' implicit discount rates are not always small positive numbers that are constant over time and the same for all settings. The authors suggest that the conventional exponential discount model may not fully characterize the time preferences held by individuals.

Adult↗
PubMedDate not supplied

Probability judgement in medicine: discounting unspecified possibilities.

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 development 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 authors presented physicians with brief clinical scenarios describing individual patients and elicited diagnostic and prognostic probability judgments. The results showed that the physicians 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.

Bias↗
PubMedDate not supplied

Primer on medical decision analysis: Part 1--Getting started.

This paper is Part 1 of a five-part series covering practical issues in the performance of decision analysis. The intended audience is individuals who are learning how to perform decision analyses, not just read them. The series assumes familiarity with the basic concepts of decision analysis. It imparts many of the recommendations the authors have learned in teaching a one-semester course in decision analysis to graduate students. Part 1 introduces the topic and covers questions such as choosing an appropriate question, determining the tradeoff between accuracy and simplicity, and deciding on a time frame.

Decision Support Techniques↗
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Primer on medical decision analysis: Part 2--Building a tree.

This part of a five-part series covering practical issues in the performance of decision analysis outlines the basic strategies for building decision trees. The authors offer six recommendations for building and programming decision trees. Following these six recommendations will facilitate performance of the sensitivity analyses required to achieve two goals. The first is to find modeling or programming errors, a process known as "debugging" the tree. The second is to determine the robustness of the qualitative conclusions drawn from the analysis.

Decision Making, Computer-Assisted↗
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Primer on medical decision analysis: Part 3--Estimating probabilities and utilities.

This paper describes how to estimate probabilities and outcome values for decision trees. Probabilities are usually derived from published studies, but occasionally are derived from existing databases, primary data collection, or expert judgment. Outcome values represent quantitative estimates of the desirability of the outcome states, and are often expressed as utility values between 0 and 1. Utility values for different health states can be derived from the published literature, from direct measurement in appropriate subjects, or from expert opinion. Methods for assigning utilities to complex outcome states are described, and the concept of quality-adjusted life years is introduced.

Biopsy↗
PubMedDate not supplied

Primer on medical decision analysis: Part 4--Analyzing the model and interpreting the results.

This paper is the fourth of a five-part series that describes the principles of construction and evaluation of valid decision models. In this review, the authors describe the key principles of detecting and eliminating structural and programming errors in decision trees (debugging). In addition, they offer guidelines to facilitate the interpretation of analytic results of decision models.

Data Interpretation, Statistical↗
PubMedDate not supplied

Primer on medical decision analysis: Part 5--Working with Markov processes.

Clinical decisions often have long-term implications. Analysis encounter difficulties when employing conventional decision-analytic methods to model these scenarios. This occurs because probability and utility variables often change with time and conventional decision trees do not easily capture this dynamic quality. A Markov analysis performed with current computer software programs provides a flexible and convenient means of modeling long-term scenarios. However, novices should be aware of several potential pitfalls when attempting to use these programs. When deciding how to model a given clinical problem, the analyst must weigh the simplicity and clarity of a conventional tree against the fidelity of a Markov analysis. In direct comparisons, both approaches gave the same qualitative answers.

Biopsy↗
PubMedDate not supplied

Guidelines for verbal presentations of medical decision analyses.

Individuals new to decision analysis often have difficulty with oral presentations of original research projects. This article provides general guidelines on how to present effectively. Points include: 1) articulating the research issue, 2) reviewing current beliefs, 3) portraying the study question, 4) listing the main assumptions, 5) presenting the base-case analysis, 6) showing sensitivity analyses, and 7) discussing the implications. The guidelines comment on what to exclude from presentation and how best to handle audience questions. The guidelines do not replace general instruction in public speaking (or rigorous training in decision analysis), but may help students present research projects effectively.

Communication↗
PubMedDate not supplied

Cost-effectiveness of regulations against using a cellular telephone while driving.

PURPOSE: To evaluate the cost-effectiveness of regulations that prohibit using a cellular telephone while driving a motor vehicle. DESIGN: Decision analysis of risks and benefits related to cellular telephones and driving. SETTING: United States population in 1997. MEASURES: Health benefits measured as the quality-adjusted life years potentially saved. Financial benefits measured as health care and other services potentially averted. Costs of regulation measured as the lost productivity derived from willingness to pay for cellular telephone calls. RESULTS: Under base-case conditions, cellular telephone calls in the United States each day accounted for about 984 reported collisions, 1,729 total collisions, 2 deaths, 317 persons with injuries, 99 lost years of life expectancy, 161 lost quality-adjusted life years, $1 million in health care costs, and $4 million in property damage and other costs. This reflected a total of about 35 million telephone calls while driving, 70 million calling minutes, and $33 million in total value to society. The estimated cost-effectiveness ratio for a regulation restricting cellular telephone usage while driving was $300,000 per quality-adjusted life year saved, but ranged from $50,000 to $700,000 under alternative assumptions and interpretations of data. Regulations applied to teenage males could be cost-saving to society if the value of a call fell below 37 cents per minute. CONCLUSIONS: Regulations restricting cellular telephone usage while driving are less cost-effective for society than other safety measures. Nevertheless, regulations may be justifiable because the benefits and harms do not always involve the individual who has the cellular telephone. Increasing the price of a call (or adding a supplementary tax) might decrease the number of discretionary calls, be cost-saving for society, and be life-saving for individuals.

Accidents, Traffic↗
PubMedDate not supplied

Car phones and car crashes: an ecologic analysis.

OBJECTIVE: Some countries have regulations against using a cellular telephone while driving. We used ecologic analysis to evaluate cellular telephone use and motor vehicle collisions in a city without such regulations. METHODS: We studied locations in Toronto, Ontario (n = 75) that were hazardous (total collisions = 3,234) and tested whether increases in collision rates from 1984 to 1993 correlated with increases in telephone usage over the same time interval. RESULTS: Locations with the largest increases in collision rates tended to have the smallest increases in estimated cellular telephone usage. Yet extreme assumptions about potential protective effects from cellular telephones failed to explain the magnitude observed. CONCLUSIONS: The effects of cellular telephones on driving ability are small relative to the biases in ecologic analysis. Claims from industry, which argue that cellular telephones are not dangerous based on ecologic analysis, can be misleading in the policy debate about whether to regulate cellular telephone use while driving.

Accidents, Traffic↗