Dennis J. Mazur

Patients’ interpretations of probability terms

Study objectives:To assess the meanings ascribed by patients to qualitative expressions of probability commonly used in medical care and to determine patient preferences for obtaining information when communicating with their physicians about medical risk numerically and/or qualitatively.Design:Cross-sectional survey of consecutive patients.Setting:A university-based Department of Veterans Affairs medical center.Participants:133 patients sequentially seen in a general medicine clinic.Measurements and results:Subjects were given a randomly ordered list of 12 common terms, each a qualitative expression of probability. They were asked to indicate what they understood to be the numerical meaning of each word. The patients’ probability estimates were found to comprise two groups of five terms each, with high intercorrelations among the probabilities assigned to the terms in each group. Mean probabilities assigned to terms in the first group all were greater than 60%, and mean probabilities assigned to terms in the second group all were below 50%. When asked whether they wanted chance information to be provided in numerical or qualitative terms, 32% reported that they wanted it only numerically; 35.3% wanted it only qualitatively; 21.8% wanted the information either way; and 8.3% wanted the information both ways.Conclusions:The numerical meanings that patients ascribe to probability terms fall into identifiable patterns. While patients vary in the actual values they assign to terms, the relative meanings of terms show consistent trends.

The role of doctor's opinion in shared decision making: what does shared decision making really mean when considering invasive medical procedures?1

Objective  The goal of this study was to gain understanding about patients’ perspectives on decision making in the context of invasive medical interventions and whether patients’ decision‐making preferences influenced the type of information they desired to be provided by physicians.

How the Manner of Presentation of Data Influences Older Patients in Determining Their Treatment Preferences

Objective: To assess how the manner of presentation of graphic data to older patients influences their treatment preferences.

Interpretation of graphic data by patients in a general medicine clinic

Objective:To assess how patients use graphic data to decide on preferences between alternative treatments. Design:Cross-sectional survey of patients, physicians, and medical students. The physicians and medical students served as a control group with which to compare the patients’ responses. Setting:A university-based Department of Veterans Affairs Medical Center. Participants:152 patients seen in a general medicine clinic, 57 medical students, and 11 physicians. Measurements and results:Subjects were given a survival graph showing the patient outcomes for two different unidentified treatments for an unidentified serious disease. They were asked to indicate which treatment they preferred and which portion(s) of the curves most influenced their preference. A large majority of both patients and health professionals preferred the treatment that had worse short-term and better long-term survival. Eleven percent of patients and 51% of health professionals identified mid-curve data (points other than the curve endpoints) as most influencing their preferences. Conclusions:A graphic survival curve appears to provide enough information to assess patient preferences between two alternative treatments. Patients appeared to differ from physicians and medical students in their interpretation of the curves.Objective:To assess how patients use graphic data to decide on preferences between alternative treatments.Design:Cross-sectional survey of patients, physicians, and medical students. The physicians and medical students served as a control group with which to compare the patients’ responses.Setting:A university-based Department of Veterans Affairs Medical Center.Participants:152 patients seen in a general medicine clinic, 57 medical students, and 11 physicians.Measurements and results:Subjects were given a survival graph showing the patient outcomes for two different unidentified treatments for an unidentified serious disease. They were asked to indicate which treatment they preferred and which portion(s) of the curves most influenced their preference. A large majority of both patients and health professionals preferred the treatment that had worse short-term and better long-term survival. Eleven percent of patients and 51% of health professionals identified mid-curve data (points other than the curve endpoints) as most influencing their preferences.Conclusions:A graphic survival curve appears to provide enough information to assess patient preferences between two alternative treatments. Patients appeared to differ from physicians and medical students in their interpretation of the curves.

Patient preferences: survival vs quality-of-life considerations.

Objective: To assess whether patients can weigh risk comparisons involving mortality and quality of life in an understandable manner based on their willingness to accept risks of complications. Design: Cross-sectional survey of patients. Setting: University-based Department of Veterans Affairs Medical Center. Participants: 230 men patients seen in a general medicine clinic. Measurements: Two survival graphs were used. Each graph contained survival curves for two alternative unidentified treatments for an unidentified medical condition. Graph 2 contained one curve that had a life expectancy that was 14% higher than the life expectancy of the corresponding curve in graph 1. Respondents were randomly assigned one of the two graphs and were asked to indicate which treatment they preferred and what risk of a change in their quality of life (urinary incontinence or impotence) they were willing to accept to achieve longer survival. Patients were also asked whether they had a history of urinary incontinence or impotence. Results and conclusions: Patients tended to be unwilling to accept worse quality of life to achieve increased survival over time. For both curve comparisons, significantly more (p<0.01) patients accepted a treatment associated with higher mortality to avoid a 100% chance of incontinence than to avoid a 100% chance of impotence. Of the 75% (172/230) of patients reporting willingness to accept risk of either urinary incontinence or total impotence or both, 62% reported having at least some symptoms related to urinary incontinence or impotence. Of the 58 patients not willing to accept the complication risks, only 11% reported a history of urinary incontinence or impotence. The results show that patients are able to make distinctions about severity of morbidity, men are less willing to accept the risk of urinary incontinence than that of total impotence, and men patients who are symptomatic with urinary incontinence or impotence are more willing to accept the risks of treatment than are asymptomatic patients.Objective: To assess whether patients can weigh risk comparisons involving mortality and quality of life in an understandable manner based on their willingness to accept risks of complications.Design: Cross-sectional survey of patients.Setting: University-based Department of Veterans Affairs Medical Center.Participants: 230 men patients seen in a general medicine clinic.Measurements: Two survival graphs were used. Each graph contained survival curves for two alternative unidentified treatments for an unidentified medical condition. Graph 2 contained one curve that had a life expectancy that was 14% higher than the life expectancy of the corresponding curve in graph 1. Respondents were randomly assigned one of the two graphs and were asked to indicate which treatment they preferred and what risk of a change in their quality of life (urinary incontinence or impotence) they were willing to accept to achieve longer survival. Patients were also asked whether they had a history of urinary incontinence or impotence.Results and conclusions: Patients tended to be unwilling to accept worse quality of life to achieve increased survival over time. For both curve comparisons, significantly more (p<0.01) patients accepted a treatment associated with higher mortality to avoid a 100% chance of incontinence than to avoid a 100% chance of impotence. Of the 75% (172/230) of patients reporting willingness to accept risk of either urinary incontinence or total impotence or both, 62% reported having at least some symptoms related to urinary incontinence or impotence. Of the 58 patients not willing to accept the complication risks, only 11% reported a history of urinary incontinence or impotence.The results show that patients are able to make distinctions about severity of morbidity, men are less willing to accept the risk of urinary incontinence than that of total impotence, and men patients who are symptomatic with urinary incontinence or impotence are more willing to accept the risks of treatment than are asymptomatic patients.

How age, outcome severity, and scale influence general medicine clinic patients’ interpretations of verbal probability terms

Objective: To assess whether the type of scale used (scaling effects) and the severity of outcome (outcome severity) influence patients’ numerical interpretations of verbal probability expressions. Design: Cross-sectional survey of patients in a general medicine clinic. Setting: A university-based Department of Veterans Affairs Medical Center. Participants: 210 patients seen consecutively in a general medicine clinic. Measurements and results: The patients were randomized to scale and health outcome (complications of surgery). Two scales (a long form and a short form ) were used to expressly allow patients to choose probabilities less than 1%. The long form had a lower bound of “<1 out of 1,000,000”; the short form had a lower bound of “<1 out of 1,000.” Two complications were used: “death from anesthesia” and “severe pneumonia.” In the context of being told that their surgeon believed that the chance the complication would occur was “rare,” patients were asked to give the numerical estimate of that chance. The values elicited on both scales were significantly different for the two outcomes, with the “rare” risk of death from anesthesia being characterized as less likely than the “rare” risk of severe pneumonia (F=5.24, p=0.023). Linear regression and three-factor analysis of variance showed significant differences in the probabilities elicited for scale, outcome, and age, with older patients generally responding with higher probabilities than did younger patients. Conclusions: These findings suggest that the severity of the associated outcome and the scale used to elicit patients’ numerical estimates of verbal probability expressions influence patients’ quantitative interpretations of the verbal probability statement; and older patients respond with higher probabilities of negative outcomes than do younger patients. Future studies must continue to explore whether verbal probability expressions are adequate for communicating medical risk to patients or whether patients should be provided with numerical estimates of frequency.Objective: To assess whether the type of scale used (scaling effects) and the severity of outcome (outcome severity) influence patients’ numerical interpretations of verbal probability expressions.Design: Cross-sectional survey of patients in a general medicine clinic.Setting: A university-based Department of Veterans Affairs Medical Center.Participants: 210 patients seen consecutively in a general medicine clinic.Measurements and results: The patients were randomized to scale and health outcome (complications of surgery). Two scales (a long form and a short form ) were used to expressly allow patients to choose probabilities less than 1%. The long form had a lower bound of “<1 out of 1,000,000”; the short form had a lower bound of “<1 out of 1,000.” Two complications were used: “death from anesthesia” and “severe pneumonia.” In the context of being told that their surgeon believed that the chance the complication would occur was “rare,” patients were asked to give the numerical estimate of that chance. The values elicited on both scales were significantly different for the two outcomes, with the “rare” risk of death from anesthesia being characterized as less likely than the “rare” risk of severe pneumonia (F=5.24, p=0.023). Linear regression and three-factor analysis of variance showed significant differences in the probabilities elicited for scale, outcome, and age, with older patients generally responding with higher probabilities than did younger patients.Conclusions: These findings suggest that the severity of the associated outcome and the scale used to elicit patients’ numerical estimates of verbal probability expressions influence patients’ quantitative interpretations of the verbal probability statement; and older patients respond with higher probabilities of negative outcomes than do younger patients. Future studies must continue to explore whether verbal probability expressions are adequate for communicating medical risk to patients or whether patients should be provided with numerical estimates of frequency.

Treatment Preferences of Patients and Physicians Influences of summary Data When Framing Effects Are Controlled

The presentation of efficacy data influences preferences for treatment options. To determine how the amount of data provided to patients influenced patient decision making after framing and labeling effects were controlled, patients and physicians were presented results of two alternative treatments for an unidentified serious medical condition, derived from summary data of lung cancer treatment after surgery (better long-term survival) or radiation therapy (better short-term survival). These data are the same as used in previous studies of framing. When summary data at one month, one year, and five years were presented in terms of both survival and mortality, patients preferred the option that would be expected if only mortality data had been presented. When more detailed data were presented (data at six discrete time points), both patients and physicians preferred the option associated with a survival frame influence in previous studies. Thus, once framing influences are controlled, preference changes can be influenced by another attribute of summary data: the amount of data presented. Key words: cognitive attitudes; cognitive biases; data, framing effect; in formed consent; medical decision making; preferences; summary data. (Med Decis Making 1990;10:2-5)

Why the goals of informed consent are not realized: Treatise on informed consent for the primary care physician

BOTH JURISTS AND ETHICISTS base the foundations of patient informedness on patient autonomy. Judge Cardozo, l in 1912, a rgued that every human being of adult years a n d sound mind has a right to determine what shall be done with his own body; a surgeon who performs an operation without his patients consent commits an assault, for which he is liable in damages . Veatch ~ has argued that the principle of autonomy and its derivative right to self-determination provide a foundation for the informed consent requirement independent of patient risk and benefit. Although failure to obtain adequa te informed consent today is considered more in terms of negligence on the part of a physician than in terms of an intentional trespass, m a n y obstacles exist in adequa te ly informing patients a n d in encouraging autonomous patient participation in decision making involving medical risk. Important developments in the evolution of patient informedness have occurred since the late 1950s, s when the term informed consent was a d d e d to the legal lexicon. Court cases at both Federal and state levels have developed s tandards for informed consent and have focused on what information physicians should give patients. Ethicists 4 have emphasized patient unders tanding and participation in decision making. In addition, there are pragmatic constraints on pa t ien t -phys ic ian decision making: the goal of involving patients in decisions about their own care is most difficult to rea]iTe in acutely ill hospita]i7ed patients, after diagnosis and before treatment. s This paper examines arguments why the ambulatory care setting m a y hold promise for exploring solutions to problems patients and physicians encounter in communicating about medical risk. Prior to examining cognitive approaches to communication about medical risk, it is helpful to review the s tandards for medical risk disclosure as they have evolved in the med ica l l ega l doctrine of informed consent.

A National Survey of Grading Systems Used in Medicine Clerkships.

To better understand the variety in U.S. medicine clerkship grading terminology, the number of grading levels, and the distribution of grades within each level, the authors surveyed medicine clerkship directors in the United States and Puerto Rico in 1986 and 1987. Completed questionnaires were returned from 101 of the 124 medical schools (81%). Descriptor grades were the most commonly used form of grading of medicine clerks, used in 68 of the 101 responding schools; letter grades were used by another 28 of the schools; and four schools used a numerical grading system. Although descriptor grades were most commonly used for grading medicine clerks, there was lack of consistency in their use between schools. The authors discuss the data related to letter grades and descriptor grades across this representative sample of U.S. medical schools.

The procedural and interpretive skills that third-year medicine clerks should master: views of medicine clerkship directors.

The authors surveyed medicine clerkship directors to determine which procedural and interpretive skills they felt third-year medical students should acquire. Of the 101 (81%) who responded, 91 felt that specific procedural and interpretive skills should be achieved by the end of the third-year medicine clerkship. Twenty-seven percent of these 91 reported having students keep a record of their activities; 35% reported testing students in the interpretation of various tests used in the evaluation of hospitalized patients on medicine services; and one clerkship director reported that his students were tested in their abilities to perform procedures. There was substantial disagreement by medicine clerkship directors over the procedural and test/study-interpretation skills in which medicine clerks should become proficient during the third-year medicine clerkship.