Framing effects in choices between multioutcome life-expectancy lotteries

AIM

To explore framing or editing effects and a method to debias framing in a clinical context.

METHOD

Clinical scenarios using multioutcome life-expectancy lotteries of equal value required choices between two supplementary drugs that either prolonged or shortened life from the 20-year beneficial effect of a baseline drug. The effects of these supplementary drugs were presented in two conditions, using a between-subjects design. In segregated editing (n = 116) the effects were presented separately from the effects of the baseline drug. In integrated editing (n = 100), effects of supplementary and baseline drugs were combined in the lottery presentation. Each subject responded to 30 problems. To explore one method of debiasing, another 100 subjects made choices after viewing both segregated and integrated editings of 20 problems (dual framing).

RESULTS

Statistically significant preference reversals between segregated and integrated editing of pure lotteries occurred only when one framing placed outcomes in the gain domain, and the other framing placed them in the loss domain. When both editings resulted in gain-domain outcomes only, there was no framing effect. There was a related relationship of framing-effect shifts from losses to gains in mixed-lottery-choice problems. Responses to the dual framing condition did not consistently coincide with responses to either single framing. In some situations, dual framing eliminated or lessened framing effects.

CONCLUSION

The results support two components of prospect theory, coding outcomes as gains or losses from a reference point, and an s-shaped utility function (concave in gain, convex in loss domains). Presenting both alternative editings of a complex situation prior to choice more fully informs the decision maker and may help to reduce framing effects. Given the extent to which preferences shift in response to alternative presentations, it is unclear which choice represents the subject's "true preferences."

Are more options always better? The attraction effect in physicians' decisions about medications

Consumer choice research has shown that, contrary to normative theory, the introduction of an inferior alternative to an existing choice set can increase the likelihood that one of the original alternatives will be chosen. This phenomenon, the attraction effect, is relevant to physician decision making, particularly when the physician is in the role of a consumer who must make decisions about prescribing medications when a number of alternatives are available. To investigate the attraction effect in physician decision making, 40 internal medicine residents reviewed three patient cases (concerning depression, sinusitis, and vaginitis) and then chose the most appropriate medication for each patient. In some versions of the cases, two medication options were available. Other versions included a third medication (the decoy) that was inferior in every way to one of the original options (the target) but not to the other (the competitor). The results showed that addition of the "decoy" medication increased the likelihood of choosing the target medication. That is, the attraction effect does occur in physicians' decisions about medications. Physicians should be aware of this bias when evaluating or suggesting several similarly attractive medications or treatment options for the same medical condition.

Time preferences and preventive health behavior: acceptance of the influenza vaccine

BACKGROUND

Many preventive health behaviors involve immediate costs and delayed benefits. Time preference is the extent to which decision makers value future outcomes relative to immediate ones. Consequently, people with future-oriented time preferences should be more likely to adopt preventive measures. The relationship between time preferences and acceptance of a free influenza vaccination was examined.

SAMPLE

The participants were 412 corporate employees who were offered free influenza vaccinations at their workplace.

MEASURES

Participants' time preferences were measured in each of two domains: money and health. They also reported on whether they had accepted the influenza vaccination and their beliefs and attitudes about the vaccine.

RESULTS

There was a small (OR = 2.38) relationship of vaccination acceptance to monetary time preferences but not to the health time-preference measures. Other variables, such as perceived effectiveness of the vaccine, were more predictive.

CONCLUSION

This study provides some evidence of a small relationship between time preferences and preventive health behavior.

A multi-attribute model of prostate cancer patient's preferences for health states

Multi-attribute utility theory (MAUT) provides a way to model decisions involving trade-offs among different aspects or goals of a problem. We used MAUT to model prostate cancer patients' preferences for their own health state and we compared this model to patients' global judgments of health state utility. 57 patients with prostate cancer (mean age = 70) at two Chicago Veterans Administration health clinics were asked to evaluate health states described in terms of five health attributes affected by prostate cancer: pain, mood, sexual function, bladder and bowel function, and fatigue and energy. Each attribute had three levels that were used to form three clinically realistic health state descriptions (A = high, B = moderate, C = low). A fourth personalized health description (P) matched the patient's current health. We first measured patients' preferences using time trade-off (TTO) judgments for the three health states (A, B, and C) and for their own current health state (P). The TTO for the patient's own health state (P) was standardized by comparing it to TTO judgments for states A and C. We next constructed a multi-attribute model using the relative importance of the five attributes. The MAU scores were moderately correlated with the TTO preference judgments for the personalized state (Pearson r = 0.38, N = 57, p < 0.01). Thus, patients' preference judgments are moderately consistent and systematic. MAUT appears to be a potentially feasible method for evaluating preferences of prostate cancer patients and may prove helpful in assisting with patient decision making.

Formation of a primitive ectoderm like cell population, EPL cells, from ES cells in response to biologically derived factors

The primitive ectoderm of the mouse embryo arises from the inner cell mass between 4.75 and 5.25 days post coitum, around the time of implantation. Positioned at a pivotal time in development, just prior to formation of the three germ layers of the embryo proper, the primitive ectoderm responds directly to the signals generated during gastrulation. We have identified a conditioned medium, MEDII, which caused the homogeneous conversion of ES cells to a morphologically distinct cell population, termed early primitive ectoderm-like (EPL) cells. EPL cells expressed the pluripotent cell markers Oct4, SSEA1 and alkaline phosphatase. However, the formation of EPL cells was accompanied by alterations in Fgf5, Gbx2 and Rex1 expression, a loss in chimaera forming ability, changes in factor responsiveness and modified differentiation capabilities, all consistent with the identification of EPL cells as equivalent to the primitive ectoderm population of the 5.5 to 6.0 days post coitum embryo. EPL cell formation could be reversed in the presence of LIF and withdrawal of MEDII, which suggested that EPL cell formation was not a terminal differentiation event but reflected the ability of pluripotent cells to adopt distinct cell states in response to specific factors. Partial purification of MEDII revealed the presence of two separable biological activities, both of which were required for the induction and maintenance of EPL cells. We show here the first demonstration of uniform differentiation of ES cells in response to biological factors. The formation of primitive ectoderm, both in vivo and in vitro, appears to be an obligatory step in the differentiation of the inner cell mass or ES cells into cell lineages of the embryonic germ layers. EPL cells potentially represent a model for the development of lineage specific differentiation protocols and analysis of gastrulation at a molecular level. An understanding of the active components of MEDII may provide a route for the identification of factors which induce primitive ectoderm formation in vivo.

Cytological aspects of antimicrobial antibiosis. I. Cytological changes associated with the exposure of Escherichia coli to colistin sulfate

Chapman, George B. (Cornell University Medical College, New York, N.Y.). Cytological aspects of antimicrobial antibiosis. I. Cytological changes associated with the exposure of Escherichia coli to colistin sulfate. J. Bacteriol. 84:169-179. 1962-Broth cultures of Escherichia coli were exposed to different concentrations of the antibiotic colistin sulfate for various lengths of time. Control (untreated) and treated cells were fixed, dehydrated, and embedded in methacrylate or Epon. Ultrathin sections were examined in an RCA EMU2-D electron microscope. Two conspicuous cytological changes were noted. First, the nuclear material disappeared from its normal sites and was no longer demonstrable. Second, the cytoplasm lost its granularity and became homogeneous. Cells which showed these changes were nonviable.

Cytological aspects of antimicrobial antibiosis. I. Cytological changes associated with the exposure of Escherichia coli to colistin sulfate

Chapman, George B. (Cornell University Medical College, New York, N.Y.). Cytological aspects of antimicrobial antibiosis. I. Cytological changes associated with the exposure of Escherichia coli to colistin sulfate. J. Bacteriol. 84:169-179. 1962-Broth cultures of Escherichia coli were exposed to different concentrations of the antibiotic colistin sulfate for various lengths of time. Control (untreated) and treated cells were fixed, dehydrated, and embedded in methacrylate or Epon. Ultrathin sections were examined in an RCA EMU2-D electron microscope. Two conspicuous cytological changes were noted. First, the nuclear material disappeared from its normal sites and was no longer demonstrable. Second, the cytoplasm lost its granularity and became homogeneous. Cells which showed these changes were nonviable.

Clinical diagnosis and the order of information

BACKGROUND

Information order can influence judgment. However, it remains unclear whether the order of clinical data affects physicians' interpretations of these data when they are engaged in familiar diagnostic tasks.

METHODS

Of 400 randomly selected family physicians who were given a questionnaire involving a brief written scenario about a young woman with acute dysuria, 315 (79%) returned usable responses. The physicians had been randomized into two groups, and both groups had received the same clinical information but in different orders. After learning the patient's chief complaint, physicians received either the patient's history and physical examination results followed by the laboratory data (the H&P-first group) or the laboratory data followed by the history and physical examination results (the H&P-last group). The results of the history and physical examination were supportive of the diagnosis of UTI, while the laboratory data were not. All physicians judged the probability of a urinary tract infection (UTI) after each piece of information.

RESULTS

The two groups had similar mean estimates of the probability of a UTI after learning the chief complaint (67.4% vs 67.8%, p = 0.85). At the end of the scenario, the H&P-first group judged UTI to be less likely than did the H&P-last group (50.9% vs 59.1%, p = 0.03) despite having identical information. Comparison of the mean likelihood ratios attributed to the clinical information showed that the H&P-first group gave less weight to the history and physical than did the H&P-last group (p = 0.04).

CONCLUSIONS

The order in which clinical information was presented influenced physicians' estimates of the probability of disease. The clinical history and physical examination were given more weight by physicians who received this information last.

Shear stress gradient over endothelial cells in a curved microchannel system

Our purpose was to test a scale model of the microcirculation by measuring the shear forces to which endothelial cells were exposed, and comparing this to computer simulations. In vitro experiments were performed to measure the 2-dimensional projected velocity profile along endothelial cell lined microchannels (D-shaped, 10-30 microns radius, n = 15), or in microchannels without endothelial cells (n = 18). Microchannels were perfused with fluorescently labeled microspheres (0.5 micron dia., < 1%) suspended in cell culture media. The velocity of individual microspheres was obtained off-line (videorecording), using an interactive software program; velocity was determined as the distance traveled in one video field (1/60 s). Mass balance was verified in the microchannels by comparing the microsphere velocities to the perfusion pump rate. In confluent endothelial cell lined microchannels, a velocity profile was obtained as microspheres passed an endothelial cell nucleus (identified by fluorescent dye), and again, for a paired region 100 microns away without nuclei (cytoplasm region). The velocity profile was significantly shifted and sharpened by the endothelial cell nucleus, as anticipated. Over the nucleus, data are consistent with a normal sized nucleus extending into the lumen, further confirming that this scale model can be used to determine the wall shear stress to which endothelial cells are exposed. Using the experimental bulk phase fluid parameters as boundary conditions, we used computational fluid dynamics (CFD) to predict the expected wall shear stress gradient along an endothelial cell lined D-shaped tube. The wall shear stress gradient over the nucleus was 2-fold greater in the radial versus axial directions, and was sensitive to lateral versus midline positioned nuclei.

Prostate cancer patients' utilities for health states: how it looks depends on where you stand

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).

Flow resistance and drag forces due to multiple adherent leukocytes in postcapillary vessels

Computational fluid dynamics was used to model flow past multiple adherent leukocytes in postcapillary size vessels. A finite-element package was used to solve the Navier-Stokes equations for low Reynolds number flow of a Newtonian fluid past spheres adhering to the wall of a cylindrical vessel. We determined the effects of sphere number, relative geometry, and spacing on the flow resistance in the vessel and the fluid flow drag force acting to sweep the sphere off the vessel wall. The computations show that when adherent leukocytes are aligned on the same side of the vessel, the drag force on each of the interacting leukocytes is less than the drag force on an isolated adherent leukocyte and can decrease by up to 50%. The magnitude of the reduction depends on the ratio of leukocyte to blood vessel diameter and distance between adherent leukocytes. However, there is an increase in the drag force when leukocytes adhere to opposite sides of the vessel wall. The increase in resistance generated by adherent leukocytes in vessels of various sizes is calculated from the computational results. The resistance increases with decreasing vessel size and is most pronounced when leukocytes adhere to opposite sides of the vessel.

The mouse homeobox gene, Gbx2: genomic organization and expression in pluripotent cells in vitro and in vivo

The Gbx2 homeodomain is widely conserved in metazoans. We investigated the mouse Gbx2 locus by isolation and characterization of genomic clones and by physical localization to the genome. The Gbx2 gene contained a single intron that separated the proposed functional protein domains. This organization was conserved with human GBX2. Physical localization of Gbx2 to Chromosome 1C5-E1 indicated that the genomic relationship between the linked Gbx2 and En1 genes differs between mouse and human, making it unlikely to be of functional significance. We also extended the known expression pattern of Gbx2 beyond the gastrulation stage embryo and the developing CNS to pluripotent cells in vitro and in vivo. Gbx2 expression was demonstrated in undifferentiated embryonic stem cells but was downregulated in differentiated cell populations. In the embryo, Gbx2 expression was detected before primitive streak formation, in the inner cell mass of the preimplantation embryo. Gbx2 is therefore a candidate control gene for cell pluripotency and differentiation in the embryo.

A comparison of perspectives on prostate cancer: analysis of utility assessments of patients and physicians

BACKGROUND

Quality-of-life considerations are important in metastatic prostate cancer. In this study, we interviewed physicians and patients about their assessments and expectations on quality of life as metastatic prostate cancer progresses.

METHODS

Physicians and patients made utility assessments of three hypothetical health states for metastatic disease using the time trade-off technique. Scores were bounded on a scale from 0.0 (death) to 1.0 (perfect health).

RESULTS

Patients rated each of the health states as less desirable than the physicians.

CONCLUSIONS

Physicians and patients differ in their perspectives on expected quality of life with metastatic prostate cancer. Our results emphasize the need to assess patients' utilities directly.

Model studies of leukocyte-endothelium-blood interactions. II. Hemodynamic impact of leukocytes adherent to the wall of post-capillary vessels

Computational fluid dynamics (CFD) and large scale model experiments were used to analyze the hemodynamic impact of leukocytes adherent to the wall of post-capillary venules. Using a large scale model and, with the aid of a finite element package, solving the Navier Stokes equations for low Reynolds number flow in a cylinder past an adherent sphere, we have developed a dimensionless correlation which permits the estimation of the pressure drop across an adherent leukocyte in an in vivo vessel. This relationship is: f.Re = exp[2.877+4.630 (d/D)4] where f is the Fanning friction factor, Re is the Reynolds number and d/D is the leukocyte to vessel diameter ratio. The friction factor is proportional to the pressure drop across the leukocyte, and does not significantly increase until d/D is greater than 0.5, and then increases rapidly with increasing d/D. Computations indicate that the length of the disturbed flow region generated by an adherent leukocyte increases with decreasing vessel size. The average wall stress in the disturbed flow region remains constant, and equal to the wall stress in the undisturbed region for d/D less than approximately 0.5. For d/D greater than 0.5, the average wall stress in the disturbed flow region increases rapidly with increasing d/D. There is an even larger increase, up to five times greater than the average disturbed stress, in the peak wall stress in the disturbed flow region. This indicates that significant wall stress gradients can be generated by an adherent leukocyte in post-capillary size vessels.

An oncology patient's choice to forgo nonvolitional nutrition support: ethical considerations

A 76-year-old patient with metastatic carcinoid tumor who had difficulty tolerating an oral diet and jejunostomy feedings became dehydrated and failed to thrive. His jejunostomy feeding regimen was manipulated to improve tolerance without success. Although his medical condition was untreatable, he was not considered terminally ill, and he was determined to be a reasonable candidate for home total parenteral nutrition (HTPN). However, he thought HTPN was an "excessive measure," and despite lengthy discussions with him by members of both the Hematology/Oncology and Nutrition Support services about the potential benefits of HTPN, he refused any further interventions involving nonvolitional nutrition support (jejunostomy feedings and HTPN). He was discharged to home receiving an oral diet as tolerated in the care of his family and hospice. This case illustrates the ethical considerations surrounding a patient's decision to forgo medical care that might prolong life.

Temporal discounting and utility for health and money

In 3 experiments, choices for hypothetical amounts of future health and money showed that, contrary to normative discounted utility theory, the temporal discount rate, or annual percentage increase in value needed to offset a delay, differed for the 2 domains. Domain independence, defined as the low correlation between health and money discount rates relative to the consistency within each domain, was not due to different utility functions for health and money. Consistent with other research, these results suggest that decision domain affects the cognitive processes used. Despite this domain difference, there were some similarities between the 2 domains. Both health and money decisions revealed that discount rates were larger for short delays, small magnitudes, and gains as compared with losses.

Validation of the Edinburgh Postnatal Depression Scale (EPDS) in non-postnatal women

This paper reports the validation of the EPDS against a Research Diagnostic Criteria diagnosis of Major and Minor depression. The EPDS was administered to non-postnatal women with older children (mean age of youngest child 3 years 9 months) and to postnatal women (baby aged 6 months). All who scored 9 or above and one third of low scorers were interviewed, using Goldberg's Clinical Interview Schedule. The study confirmed good user acceptability of the EPDS when administered as a postal questionnaire (92% response rate). The EPDS was found to have satisfactory sensitivity (79%) and specificity (85%). Our findings suggest that the EPDS take a place alongside other screening scales for depression in Community samples. It is proposed that when used in these settings it is referred to as the Edinburgh Depression Scale.

Temporal discounting and utility for health and money

In 3 experiments, choices for hypothetical amounts of future health and money showed that, contrary to normative discounted utility theory, the temporal discount rate, or annual percentage increase in value needed to offset a delay, differed for the 2 domains. Domain independence, defined as the low correlation between health and money discount rates relative to the consistency within each domain, was not due to different utility functions for health and money. Consistent with other research, these results suggest that decision domain affects the cognitive processes used. Despite this domain difference, there were some similarities between the 2 domains. Both health and money decisions revealed that discount rates were larger for short delays, small magnitudes, and gains as compared with losses.

Malabsorption associated with surgical procedures and its treatment

Signs and symptoms of malabsorption after surgical procedures can be subtle and recognized late. This article reviews some of the more common surgical procedures potentially associated with malabsorption and suggests techniques of nutrition intervention. Early recognition, and preferably preventative care, should result in improved patient outcome.