| 1. |
- Backlund, Lars G., et al.
(författare)
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Improving Fast and Frugal Modeling in Relation to Regression Analysis : Test of 3 Models for Medical Decision Making
- 2009
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Ingår i: Medical decision making. - : Sage Publications. - 0272-989X .- 1552-681X. ; 29:1, s. 140-148
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Tidskriftsartikel (refereegranskat)abstract
- Background. A matching heuristic (MH) model of decision makinghas been evaluated previously in a series of studies on medicaldecision making. The authors' purpose is to evaluate an extendedMH model that considers the prevalence of cue values. Methods.Data from 2 previous studies were reanalyzed, one on judgmentsregarding drug treatment of hyperlipidemia and the other ondiagnosing heart failure. The original MH model and the extendedMH model were compared with logistic regression (LR) in termsof fit to actual judgments, number of cues, and the extent towhich the cues were consistent with clinical guidelines. Results. There was a slightly better fit with LR compared with MH. Theextended MH model gave a significantly better fit than the originalMH model in the drug treatment task. In the diagnostic task,the number of cues was significantly lower in the MH modelscompared to LR, whereas in the therapeutic task, LR could beless or more frugal than the matching heuristic models dependingon the significance level chosen for inclusion of cues. Forthe original MH model, but not for the extended MH model orLR, the most important cues in the drug treatment task wereoften used in a direction contrary to treatment guidelines.Conclusions. The extended MH model represents an improvementin that prevalence of cue values is adequately taken into account,which in turn may result in better fit and in better agreementwith medical guidelines in the evaluation of cues.
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| 2. |
- Bleichrodt, Han, et al.
(författare)
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An Experimental Test of a Theoretical Foundation for Rating-scale Valuations
- 1997
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Ingår i: Medical decision making. - : SAGE. - 1552-681X .- 0272-989X. ; 17:2, s. 208-216
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Tidskriftsartikel (refereegranskat)abstract
- A major advantage of using a rating scale in health-utility measurement is its practical applicability: the method is relatively easy to understand, and various health states can be assessed simultaneously. However, a theoretical foundation for rating-scale valuations has not been established. The primary aim of this paper is to present a theoretical foundation for rating-scale valuations based on the theory of measurable value functions and to provide a consistency test to see whether rating-scale valuations do indeed elicit a measurable value function. If rating-scale valuations elicit a measurable value function, then Dyer and Sarin have shown how they are related to von Neumann-Morgenstern (vNM) utilities. The appropriate technique to measure vNM utilities is the standard gamble. Torrance has suggested that rating-scale valuations and standard-gamble valuations are related by a power function. A secondary aim of this paper is to examine the relationship between rating-scale valuations and standard-gamble valuations hypothesized by Torrance. An experiment was designed to test consistency of rating-scale valuations and the relationship between rating-scale valuations and standard-gamble valuations. The experiment tested whether rating-scale valuations are independent of the context in which they are elicited, as they should be if they elicit points on a measurable value function. 80 Swedish and 92 Dutch respondents participated in the experiment. The results showed that rating-scale valuations depend on the number of preferred alternatives in the task and thus violate a basic property of measurable value functions. The estimation of the power function did not result in stable results: parameter estimates varied, in some cases there was indication of misspecification, and in most cases there was indication of heteroskedastic errors. The implications of these findings for the common use of rating-scale valuations in cost-utility analysis are serious: the dependency of the rating-scale valuations on the other health states included in the task casts serious doubts on the validity of the rating-scale method. Key words: QALYs; rating scale; cost-utility analysis; medical decision making. (Med Decis Making 1997;17:208-216))
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| 3. |
- Bleichrodt, Han, et al.
(författare)
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The Validity of QALYs : An Experimental Test of Constant Proportional Tradeoff and Utility Independence
- 1997
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Ingår i: Medical decision making. - 1552-681X .- 0272-989X. ; 17:1, s. 21-32
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Tidskriftsartikel (refereegranskat)abstract
- Pliskin, Shepard, and Weinstein identified three preference conditions that ensure that quality-adjusted life years (QALYs) represent preferences over gambles over chronic health profiles. This paper presents an experimental test of the descriptive validity of two of these preference assumptions: utility independence and constant proportional tradeoff. Eighty students at the Stockholm School of Economics and 92 students at Erasmus University Rotterdam participated in the experiment. The results of the ex periment support the descriptive validity of constant proportional tradeoff: both within groups and between groups constant proportional tradeoff could not be rejected. The results are less supportive of the descriptive validity of utility independence. Within- groups utility independence was rejected. Between-groups utility independence could not be rejected, but this may have been due to a lack of statistical power. Analysis of the individual responses revealed that without adjustment for imprecision of preference, 39 respondents (22.8%) satisfied constant proportional tradeoff. Twenty-three respon dents (13.4%) satisfied utility independence without adjustment for imprecision of pref erence. However, because of the relative unfamiliarity of the respondents with both the health states to be evaluated and the methods of health-state-utility measurement, it is likely that the respondents' preferences were imprecise. Adjusted for imprecision of preference, the upper estimates of the proportions of respondents who satisfied constant proportional tradeoff and utility independence, respectively, were 90.1% (155 respondents) and 75.6% (130 respondents). Pliskin et al. further derived that if an individual's preferences satisfy both constant proportional tradeoff and utility indepen dence, then these preferences can be represented by a more general, risk-adjusted QALY model. Without adjustment for imprecision of preference, ten respondents (5.8%) satisfied both constant proportional tradeoff and utility independence. Adjusted for imprecision of preference, the upper estimate of the proportion of respondents who satisfied both constant proportional tradeoff and utility independence was 68.6% (118 respondents). The results of this study indicate that constant proportional tradeoff holds approximately. The evidence is much weaker for utility independence, however. This has important implications for the use of QALY-type measures in medical decision making. Key words: QALYs; health utility measurements; medical decision making; individual preferences. (Med Decis Making 1996;17:21-32)
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| 4. |
- Borgquist, Lars, et al.
(författare)
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The Relationship between Health-state Utilities and the SF-12 in a General Population
- 1999
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Ingår i: Medical decision making. - : SAGE. - 1552-681X .- 0272-989X. ; 19:2, s. 128-140
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Tidskriftsartikel (refereegranskat)abstract
- It would be a major advance if quality-of-life instruments could be translated into health- state utilities. The aim with this study was to investigate the relationship between the SF-12 and health-state utilities, based on responses to a postal questionnaire sent to a random sample of 8,000 inhabitants, aged 20-84 years, in the general population. The questionnaire included the SF-12, a rating-scale (RS) question, and a time-tradeoff (TTO) question; the response rate was 68%. Age, gender, and the 12 items of the SF- 12 were used as explanatory variables in a linear regression analysis of the health- state utilities. The regression models explained about 50% of the variance in the RS answers and about 25% of the variance in the TTO answers. Most of the SF-12 items were related to the health-state utilities in the expected ways, with especially strong results for the RS method. The results suggest that the SF-12 can be converted to health-state utilities, but that further work is needed to reliably estimate the conversion function. Key words: health status; SF-12; rating scale; time-tradeoff; health-related quality of life; health-state utilities; population study. (Med Decis Making 1999;19:128- 140)
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| 5. |
- Cao, Qi, et al.
(författare)
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Continuous-Time Semi-Markov Models in Health Economic Decision Making: An Illustrative Example in Heart Failure Disease Management
- 2016
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Ingår i: Medical decision making. - : SAGE PUBLICATIONS INC. - 0272-989X .- 1552-681X. ; 36:1, s. 59-71
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Tidskriftsartikel (refereegranskat)abstract
- Continuous-time state transition models may end up having large unwieldy structures when trying to represent all relevant stages of clinical disease processes by means of a standard Markov model. In such situations, a more parsimonious, and therefore easier-to-grasp, model of a patients disease progression can often be obtained by assuming that the future state transitions do not depend only on the present state (Markov assumption) but also on the past through time since entry in the present state. Despite that these so-called semi-Markov models are still relatively straightforward to specify and implement, they are not yet routinely applied in health economic evaluation to assess the cost-effectiveness of alternative interventions. To facilitate a better understanding of this type of model among applied health economic analysts, the first part of this article provides a detailed discussion of what the semi-Markov model entails and how such models can be specified in an intuitive way by adopting an approach called vertical modeling. In the second part of the article, we use this approach to construct a semi-Markov model for assessing the long-term cost-effectiveness of 3 disease management programs for heart failure. Compared with a standard Markov model with the same disease states, our proposed semi-Markov model fitted the observed data much better. When subsequently extrapolating beyond the clinical trial period, these relatively large differences in goodness-of-fit translated into almost a doubling in mean total cost and a 60-d decrease in mean survival time when using the Markov model instead of the semi-Markov model. For the disease process considered in our case study, the semi-Markov model thus provided a sensible balance between model parsimoniousness and computational complexity.
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| 6. |
- Caster, Ola, et al.
(författare)
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Quantitative Benefit-Risk Assessment Using Only Qualitative Information on Utilities
- 2012
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Ingår i: Medical decision making. - 0272-989X .- 1552-681X. ; 32:6, s. E1-E15
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Tidskriftsartikel (refereegranskat)abstract
- Background: Utilities of pertinent clinical outcomes are crucial variables for assessing the benefits and risks of drugs, but numerical data on utilities may be unreliable or altogether missing. We propose a method to incorporate qualitative information into a probabilistic decision analysis framework for quantitative benefit-risk assessment. Objective: To investigate whether conclusive results can be obtained when the only source of discriminating information on utilities is widely agreed upon qualitative relations, for example, ''sepsis is worse than transient headache'' or ''alleviation of disease is better without than with complications.'' Method: We used the structure and probabilities of 3 published models that were originally evaluated based on the standard metric of quality-adjusted life years (QALYs): terfenadine versus chlorpheniramine for the treatment of allergic rhinitis, MCV4 vaccination against meningococcal disease, and alosetron for irritable bowel syndrome. For each model, we identified clinically straightforward qualitative relations among the outcomes. Using Monte Carlo simulations, the resulting utility distributions were then combined with the previously specified probabilities, and the rate of preference in terms of expected utility was determined for each alternative. Results: Our approach conclusively favored MCV4 vaccination, and it was concordant with the QALY assessments for the MCV4 and terfenadine versus chlorpheniramine case studies. For alosetron, we found a possible unfavorable benefit-risk balance for highly risk-averse patients not identified in the original analysis. Conclusion: Incorporation of widely agreed upon qualitative information into quantitative benefit-risk assessment can provide for conclusive results. The methods presented should prove useful in both population and individual-level assessments, especially when numerical utility data are missing or unreliable, and constraints on time or money preclude its collection.
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| 7. |
- DiSantostefano, Rachael L., et al.
(författare)
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Can the General Public Be a Proxy for an "At-Risk" Group in a Patient Preference Study? : A Disease Prevention Example in Rheumatoid Arthritis
- 2024
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Ingår i: Medical decision making. - : Sage Publications. - 0272-989X .- 1552-681X. ; 44:2, s. 189-202
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundWhen selecting samples for patient preference studies, it may be difficult or impractical to recruit participants who are eligible for a particular treatment decision. However, a general public sample may not be an appropriate proxy.ObjectiveThis study compares preferences for rheumatoid arthritis (RA) preventive treatments between members of the general public and first-degree relatives (FDRs) of confirmed RA patients to assess whether a sample of the general public can be used as a proxy for FDRs.MethodsParticipants were asked to imagine they were experiencing arthralgia and had screening tests indicating a 60% chance of developing RA within 2 yrs. Using a discrete choice experiment, participants were offered a series of choices between no treatment and 2 unlabeled hypothetical treatments to reduce the risk of RA. To assess data quality, time to complete survey sections and comprehension questions were assessed. A random parameter logit model was used to obtain attribute-level estimates, which were used to calculate relative importance, maximum acceptable risk (MAR), and market shares of hypothetical preventive treatments.ResultsThe FDR sample (n = 298) spent more time completing the survey and performed better on comprehension questions compared with the general public sample (n = 982). The relative importance ranking was similar between the general public and FDR participant samples; however, other relative preference measures involving weights including MARs and market share differed between groups, with FDRs having numerically higher MARs.ConclusionIn the context of RA prevention, the general public (average risk) may be a reasonable proxy for a more at-risk sample (FDRs) for overall relative importance ranking but not weights. The rationale for a proxy sample should be clearly justified.HighlightsParticipants from the general public were compared to first-degree relatives on their preferences for rheumatoid arthritis (RA) preventive treatments using a discrete choice experiment.Preferences were similar between groups in terms of the most important and least important attributes of preventive treatments, with effectiveness being the most important attribute. However, relative weights differed.Attention to the survey and predicted market shares of hypothetical RA preventive treatments differed between the general public and first-degree relatives.The general public may be a reasonable proxy for an at-risk group for patient preferences ranks but not weights in the disease prevention context; however, care should be taken in sample selection for patient preference studies when choosing nonpatients.
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| 8. |
- Heintz, Emelie, 1981-, et al.
(författare)
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The impact of patients' subjective life expectancy on time trade-off valuations
- 2013
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Ingår i: Medical decision making. - : SAGE Publications (UK and US). - 0272-989X .- 1552-681X. ; 33:2, s. 261-270
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Tidskriftsartikel (refereegranskat)abstract
- Background. Quality-adjusted life-year (QALY) calculations in economic evaluations are typically based on general public or patient health state valuations elicited with the time tradeoff method (TTO). Such health state valuations elicited among the general public have been shown to be affected by respondents subjective life expectancy (SLE). This suggests that TTO exercises based on time frames other than SLE may lead to biased estimates. It has not yet been investigated whether SLE also affects patient valuations. Objective. To empirically investigate whether patients SLE affects TTO valuations of their current health state. Methods. Patients with different severities of diabetic retinopathy were asked in a telephone interview to value their own health status using TTO. The TTO time frame (t) presented was based on age- and sex-dependent actuarial life expectancy. Patients were then asked to state their SLE. Simple and multiple regression techniques were used to assess the effect of the patients SLE on their TTO responses. Results. In total, 145 patients completed the telephone interview. Patients TTO values were significantly influenced by their SLE. The TTO value decreased linearly with every additional year of difference between t and the patients SLE; that is, patients were more willing to give up years the shorter their SLE compared with t. Conclusion. Patients SLE influenced their TTO valuations, suggesting that respondents SLE may be the most appropriate time frame to use in TTO exercises in patients. The use of other time periods may bias the TTO valuations, as the respondents may experience the presented time frame as a gain or a loss. The effect seems to be larger in patient valuations than in general public valuations.
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| 9. |
- Johannesen, Kasper, et al.
(författare)
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Subcategorizing the Expected Value of Perfect Implementation to Identify When and Where to Invest in Implementation Initiatives
- 2020
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Ingår i: Medical decision making. - : Sage Publications. - 0272-989X .- 1552-681X. ; 40:3, s. 327-338
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Tidskriftsartikel (refereegranskat)abstract
- Purpose. Clinical practice variations and low implementation of effective and cost-effective health care technologies are a key challenge for health care systems and may lead to suboptimal treatment and health loss for patients. The purpose of this work was to subcategorize the expected value of perfect implementation (EVPIM) to enable estimation of the absolute and relative value of eliminating slow, low, and delayed implementation. Methods. Building on the EVPIM framework, this work defines EVPIM subcategories to estimate the expected value of eliminating slow, low, or delayed implementation. The work also shows how information on regional implementation patterns can be used to estimate the value of eliminating regional implementation variation. The application of this subcategorization is illustrated by a case study of the implementation of an antiplatelet therapy for the secondary prevention after myocardial infarction in Sweden. Incremental net benefit (INB) estimates are based on published cost-effectiveness assessments and a threshold of SEK 250,000 (22,300) pound per quality-adjusted life year (QALY). Results. In the case study, slow, low, and delayed implementation was estimated to represent 22%, 34%, and 44% of the total population EVPIM (2941 QALYs or SEK 735 million), respectively. The value of eliminating implementation variation across health care regions was estimated to 39% of total EVPIM (1138 QALYs). Conclusion. Subcategorizing EVPIM estimates the absolute and relative value of eliminating different parts of suboptimal implementation. By doing so, this approach could help decision makers to identify which parts of suboptimal implementation are contributing most to total EVPIM and provide the basis for assessing the cost and benefit of implementation activities that may address these in future implementation of health care interventions.
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| 10. |
- Johannesson, Magnus, et al.
(författare)
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Are Healthy-years Equivalents an Improvement over Quality-adjusted Life Years?
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Ingår i: Medical decision making. - 1552-681X .- 0272-989X. ; 13:4, s. 281-286
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Tidskriftsartikel (refereegranskat)abstract
- The construct of the healthy-years equivalent (HYE) has been proposed as an alternative to the quality-adjusted life year (QALY) on the grounds that it avoids certain restrictive assumptions about preferences and also incorporates attitudes toward risk. The authors review the construct of the QALY, including both the commonly used risk-neutral formulation and the more general formulation that permits risk aversion (or risk preference) with respect to remaining life years. They show that the HYE adds flexibility to the risk-neutral form of the QALY by permitting the rate of tradeoff between life years and quality of life to depend on the life span, albeit at the cost of eliciting numerous additional time-tradeoff assessments. However, the claim that the HYE incorporates attitudes toward risk is incorrect, and the proposed two-stage procedure to measure HYEs is neither necessary nor sufficient to in corporate attitudes toward risk. In fact, the HYE assumes risk neutrality with respect to healthy years of life and, therefore, is less suitable for decisions under uncertainty than is the general (risk-averse) form of the QALY. Key words: quality-adjusted life years; healthy- years equivalents; economic evaluation; medical decision making; individual preferences; time-tradeoff; standard gamble; utility theory. (Med Decis Making 1993;13:281-286)
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