Comparing community-preference-based and direct standard gamble utility scores: evidence from elective total hip arthroplasty

OBJECTIVES: Do utility scores based on patient preferences and scores based on community preferences agree? The purpose is to assess agreement between directly measured standard gamble (SG) utility scores and utility scores from the Health Utilities Index Mark 2 (HUI2) and Mark 3 (HUI3) systems. METHODS: Patients were assessed repeatedly throughout the process of waiting to see a surgeon, waiting for surgery, and recovery after total hip arthroplasty (THA). Group mean scores are compared using paired t-tests. Agreement is assessed using the intraclass correlation coefficient (ICC). RESULTS: The mean SG, HUI2, and HUI3 (SD) scores at assessment 1 are 0.62 (0.31), 0.62 (0.19), and 0.52 (0.21); n=103. At assessment 2, the means are 0.67 (0.30), 0.68 (0.30), and 0.58 (0.22); n=84. There are no statistically significant differences between group mean SG and HUI2 scores. Mean SG and HUI3 scores are significantly different. ICCs are low. CONCLUSIONS: At the mean level for the group, SG and HUI2 scores match closely. At the individual level, agreement is poor. HUI2 scores were greater than HUI3 scores. HUI2 and HUI3 are appropriate for group level analyses relying on community preferences but are not a good substitute for directly measured utility scores at the individual level.     

A comparison of HUI2 and HUI3 utility scores in Alzheimer's disease.

PURPOSE: The Health Utilities Index (HUI) is a generic, multiattribute, preference-based health-status classification system. The HUI Mark 3 (HUI3) differs from the earlier HUI2 by modifying attributes and allowing more flexibility for capturing high levels of impairment. The authors compared HUI2 and HUI3 scores of patients with Alzheimer's disease (AD) and caregivers, and contrasted results of a cost-effectiveness analysis of new drugs for AD using the two systems. METHODS: In a cross-sectional study of 679 AD patient/caregiver pairs, stratified by patient's disease stage (questionable/mild/moderate/severe/profound/terminal) and setting (community/assisted living/nursing home), caregivers completed the combined HUI2/HUI3 questionnaire as proxy respondents for patients and for themselves. RESULTS: Mean (SD) global utility scores for patients were lower on the HUI3 (0.22[0.26]) than on the HUI2 (0.53 [0.21]). Patient HUI3 utility scores ranged from 0.47(0.24) for questionable AD to -0.23 (0.08) for terminal AD, compared with a range of 0.73 (0.15) to 0.14 (0.07) for the HUI2. Among the 203 patients in the severe, profound, and terminal stages, 96 (48%) had negative global HUI3 utility scores, while none had a negative HUI2 score. The utility scores for caregivers were similar on the HUI3 (0.87 [0.14]) and HUI2 (0.87 [0.11]). Cost-effectiveness analysis of a new medication to treat AD showed somewhat more favorable results using the HUI3. CONCLUSIONS: The HUI2 and HUI3 discriminate well across AD stages. Compared with the HUI2, the HUI3 yields lower global utility scores for patients with AD, and more scores for states judged worse than dead. The HUI3 may yield substantially different results from the HUI2, particularly for persons who have serious cognitive impairments such as AD.     

Paper standard gamble: a paper-based measure of standard gamble utility for current health

OBJECTIVES: To develop and validate a paper-based instrument that is simple to administer and produces a reliable estimate of patient standard gamble (SG) utilities for current health status. METHODS: A 1-page paper questionnaire instrument, paper standard gamble (PSG), was designed to estimate SG utilities. We performed two studies to assess the validity of PSG. First we compared PSG and SG utilities for current health in patients with prostate cancer. They randomly received either PSG followed by SG or vice versa, always with an intervening SF-12. In the second validity study, we assessed the test-retest reliability of PSG by administering it to prostate cancer patients twice, at least 2 weeks apart. RESULTS: In the first study, utilities were assessed in 64 men (32 per SG/PSG order group). A paired-comparison t test suggested no difference between SG and PSG (mean difference = -0.007; 95% confidence interval (Cl), -0.022 to 0.008). The concordance correlation coefficient was 0.92 (95% Cl, 0.79 to 0.99). In the second study, test and retest PSGs were available for 184 patients. The concordance correlation coefficient was 0.88 (95% Cl, 0.73 to 0.94). CONCLUSIONS: These data suggest that PSG may serve as a reliable substitute for SG when current health utility is of interest. PSG may have particular advantages for acquisition of health-related quality-of-life data in longitudinal studies.     

Comparing utility scores before and after hearing-aid provision

Utility scores were estimated for 609 hearing-impaired adults who completed EQ-5D, Health Utilities Index Mark III (HUI3) and SF-6D survey instruments both before and after being provided with a hearing aid. Pre-intervention, the mean utility scores for EQ-5D (0.80) and SF-6D (0.78) were significantly higher than the mean HUI3 utility score (0.58). Post-intervention, the mean improvement in the HUI3 (0.06 change) was significantly higher than the mean improvement according to the EQ-5D (0.01 change) or SF-6D (0.01 change). The estimated cost effectiveness of hearing-aid provision is therefore likely to be dependent on which instrument is used to measure utility.     

The standard gamble method: what is being measured and how it is interpreted.

OBJECTIVE. The Standard Gamble (SG) technique is recommended for measurement of individuals' preferences under uncertainty and to express the outcome of different therapeutic choices in utility values to be used in clinical decision analysis and health program evaluation. The article alerts users of this technique to problems stemming from inappropriate interpretation of results of measurements using the SG method. STUDY DESIGN. We review different situations where the SG method is used to measure individuals' or group preferences. PRINCIPAL FINDINGS. We demonstrate inappropriate interpretation of the time dimension at the individual level; issues stemming from the aggregation of individual utility values measured using different time horizons; the potential for double counting of the time preference effect when discounting future quality-adjusted life years (QALYs); and problems associated with using the SG technique to measure temporary health states. CONCLUSIONS. The inappropriate interpretations stem mainly either from ignoring the time dimension, which is inextricably bound to the health of the individual, or form adding assumptions, in addition to those required by von Neumann-Morgenstern (vNM) utility theory, that are not supported by empirical evidence. An alternative approach to QALYs, the healthy years equivalent (HYE), which incorporates the SG but avoids many of these problems, is described.     

A comparison of standard gamble, time trade-off, and adjusted time trade-off scores

OBJECTIVE: To adjust patients' time trade-off (TTO) scores using information on their utility functions for survival time to derive a measure of health state utility equivalent to the standard gamble (SG). METHODS: A sample of 199 cardiovascular patients were asked three TTO and SG questions (to assess their own health state), and three certainty equivalent questions (to assess their utility function for survival time) in an interview. RESULTS: Patient's utility functions for time were increasingly concave, but being unable to model this successfully, a constant function with an averaged level of concavity was used. The raw TTO scores were significantly higher than SG scores, while the adjusted TTO scores were equivalent to the SG. CONCLUSIONS: Raw time trade-off scores will give biased estimates of health state utility when patients' utility functions for time are not linear, but these can be adjusted to yield true utilities. The constant proportional risk-posture assumption of the conventional QALY model, on which previous attempts to adjust time trade-offs have been based, was not supported by the data.     

Utilities measured by rating scale,time trade-off,and standard gamble: review and reference for health care professionals

Utility is a simple expression of health-related quality of life in individuals with different states of health. A number of studies on utility measurements were conducted and published in the past. We retrieved 164 English-language articles which appeared in 1966 through 1999 for a systematic review. The number of reports has been increasing at an accelerating pace, especially during the past decade. The most widely used method of utility measurement was time trade-off, TTO (40%), followed by rating scale, RS (31%) and standard gamble, SG (29%). The utility of chronic health status was more frequently reported as compared with acute health status (907 vs 86). Accordingly, frequently explored clinical categories were cardiology, neurology, nephrology, and gastroenterology. Specifically, coronary heart disease (52 utilities), physical disability due to neurological diseases (45 utilities), chronic renal failure (74 utilities), and colorectal cancer (29 utilities) were subject to utility measurement. Mental or social dysfunctioning accounted for only a small proportion (48 utilities). There is a strong tendency for RS to yield the lowest and SG to yield the highest values. We compiled an extensive list of the results of studies on utility as a reference for health care professionals in this field.     

Comparing Short Form 6D,Standard Gamble,and Health Utilities Index Mark 2 and Mark 3 utility scores: Results from total hip arthroplasty patients

Objective: The objectives are to compare SF-6D, standard gamble (SG), and Health Utilities Index (HUI) utility scores, compare change scores, and compare responsiveness. Methods: A cohort of osteoarthritis patients referred for total hip arthroplasty (THA) were evaluated at the time of referral and followed until 3months after THA. Patients were assessed using the SF-36, HUI2, HUI3, and the SG. Agreement is assessed using the intra-class correlation (ICC). Responsiveness is assessed using effect size, standardized response mean, and paired t-test. Results: Data was available for 86 patients at baseline and for 63 at both pre- and post-surgery. At baseline mean SF-6D (0.61), SG (0.62), and HUI2 (0.62) scores were similar; the mean HUI3 score (0.52) was lower. Standard deviations were 0.10, 0.32, 0.19, and 0.22. At baseline, agreement between SF-6D and SG scores was 0.13, agreement between SF-6D and HUI2 was 0.47, and agreement between SF-6D and HUI3 was 0.28. Agreement at pre- and post-surgery was similar. The change in scores between post- and pre-surgery was 0.10 for SF-6D, 0.16 for SG, 0.22 for HUI2, and 0.23 for HUI3. Effect sizes were 1.10 for HUI2, 1.08 for HUI3, 1.06 for SF-6D, and 0.48 for the SG. Conclusions: Agreement between SG scores and SF-6D and HUI scores was low. The estimate of change in utility associated with THA was lowest for SF-6D. Additional longitudinal studies to compare utility measures appear to be warranted.     

The time horizon matters: results of an exploratory study varying the timeframe in time trade-off and standard gamble utility elicitation

Introduction

The purpose of this study was to examine whether the time horizon of time trade-off (TTO) and standard gamble (SG) utility assessment influences utility scores and discrimination between health states.

Methods

In two phases, UK general population participants rated three osteoarthritis health states in TTO and SG procedures with two time horizons: (1) 10-year and (2) a time horizon derived from self-reported additional life expectancy (ALE). The two time horizons were compared in terms of mean utilities and discrimination among health states.

Results

In Phase 1, the 10-year tasks were completed by 80 participants, 35 of whom also completed utility assessment with the ALE. In Phase 2, all 101 participants completed procedures with both time horizons. Utility scores tended to be lower with the ALE than the 10-year, a difference that was statistically significant for two health states with SG in Phase 1 (P < 0.05), two health states with TTO in Phase 2 (P < 0.01), and one health state with SG in Phase 2 (P < 0.001). In Phase 1, rates of discrimination between mild and moderate osteoarthritis health states were significantly higher with the ALE than the 10-year (TTO: P = 0.03; SG: P = 0.001). This pattern of discrimination was similar in Phase 2.

Discussion

Results suggest that the time horizon could influence utility scores and discrimination among health states. When designing utility evaluations, researchers should carefully consider the time horizon so that the value of health states is accurately represented in cost-utility models.

     

The healthy-years equivalents: how to measure them using the standard gamble approach

The healthy-years equivalent (HYE) is a measure of outcome of health care programs that combines two outcomes of interest: quality of life and quantity of life. Unlike QALYs (quality-adjusted life years) HYEs fully represent patients' (or other individuals') preferences, as a result of the way they are calculated from each individual's utility function. The authors suggest an algorithm to measure the HYE of any given lifetime health profile. The algorithm is based on the classic standard gamble method to measure individuals' preferences under uncertainty, and consists of two lottery questions. Algorithms for the general case (any given lifetime health profile) and a simpler case--the chronic health state case--are provided, as is a modification of the algorithm aimed at shortening the length of the interview when an individual is faced with many possible lifetime health profiles. In addition, two questions are addressed. The first is theoretical and deals with the existence of HYE: do all lifetime health profiles, which are preferred to death, have hypothetical equivalents that can be measured in healthy years? The second is empirical and deals with the reproducibility of the measures obtained by using the measurement technique suggested. This is needed because the technique employs a combination of lottery questions that had not previously been used together. The results of an experiment performed to test the reproducibility of the measures were satisfactory.     

Translation and cultural adaptation of Health Utilities Index (HUI) Mark 2 (HUI2) and Mark 3 (HUI3) with application to survivors of childhood cancer in Brazil

Introduction: There are few publications reporting health-related quality of life (HRQL) in developing nations. Most instruments measuring HRQL have been developed in English-speaking countries. These instruments need to be culturally adapted for use in non-English-speaking countries. The HUI2 and HUI3 are generic, preference-based systems for describing health status and HRQL. Developed in Canada, the systems have been translated into more than a dozen languages and used worldwide in hundreds of studies of clinical and general populations. Methods: The Brazilian–Portuguese translation of the HUI systems was supervised by senior HUInc staff having experience with both the HUI systems and translations. The process included two independent forward translations of the multi-attribute health status classification systems and related questionnaires, consensus between translators on a forward translation, back-translation by two independent translators of the forward translation, and review of the back-translations by original developers of the HUI. The final questionnaires were tested by surveying a sample of convenience of 50 patients recruited at the Centro de Tratamento e Pesquisa–Hospital do Câncer in São Paulo, Brazil. Results: Fifty patients were enrolled in the study. No assessor, patient or nurse or physician, reported problems answering the HUI questionnaires. No significant differences were found in mean overall HUI2 or HUI3 utility scores among types of assessors. Variability in scores are similar to those from other studies in Latin America and Canada. Conclusion: Test results provide preliminary evidence that the Brazilian–Portuguese translation is acceptable, understandable, reliable and valid for assessing health-status and HRQL among survivors of cancer in childhood in Brazil.     

Maximal endurable time states and the standard gamble: more preference reversals

Background

The time trade off (TTO) method is not sensitive to maximal endurable time preferences, as preference reversals occur. The standard gamble (SG) method has not been tested regarding its sensitivity to maximal endurable time preferences.

Objective

This study investigates whether preference reversals occur for the SG method as well.

Methods

Fifty-nine respondents stated for several migraine health states their preference for living 10 or 20 years in that state. A migraine state was selected for which a respondent preferred 10–20 years, a maximal endurable time preference. Two probability equivalent gambles were obtained for the migraine states lasting 10 and 20 years, respectively. Preference reversals occurred when the gamble, equivalent to the longer duration, was preferred to the gamble equivalent to the shorter duration.

Results

Out of 59 respondents, 48 had maximal endurable time preferences. Of these 48 respondents, 34 (71 %) showed a preference reversal. This percentage differed significantly from chance, that is 50 % (P = 0.004), indicating that preference reversals occurred reliably.

Conclusion

The observed reversal rate for the standard gamble is similar to rates observed previously with the TTO method. Utility measurement of poor health states is problematic, both with the TTO and standard gamble methods.     

French Cross-Cultural Adaptation of the Health Utilities Indexes Mark 2 (HUI2) and 3 (HUI3) Classification Systems

The McMaster Health Utilities Indexes Mark 2 (HUI2) and 3 (HUI3) are multiattribute health classification systems, for which multiattribute preference functions have been developed in Canada. They provide a comprehensive instrument for use in economic evaluations and population health survey studies. This paper reports on the first results on the adaptation of the HUI2 and HUI3 systems cross-culturally and the assessment of the validity and reliability of the French self-report questionnaire in different patient populations. The cross-cultural adaptation included translation, backtranslations, an expert consensus meeting and pre-test with a few patients and healthy subjects in order to produce a conceptually equivalent French version of the 15 question self-report questionnaire and the HUI2 and HUI3 classification systems. Different groups of patients attending specialized clinics (n = 709) completed the questionnaire and another generic questionnaire (the Sickness Impact Profile (SIP)) for validity assessment. Physicians and patients were also asked for a global subjective assessment of the patient's health status. The French questionnaire was well received by the patients. The criterion and convergent validities of both classification systems (correlations with the patients' and physicians' assessments and with the responses to the SIP questionnaire) were satisfactory. The internal consistency was acceptable too (Cronbach's α = 0.81), as was the 3 day test-retest reproducibility. These first results authorize careful use of the 15 question self-report questionnaire in French. An assessment of the multiattribute preference function for the HUI3 system in France will be the study's next objective. This revised version was published online in June 2006 with corrections to the Cover Date.     

Choosing between measures: comparison of EQ-5D,HUI2 and HUI3 in persons with hearing complaints

Objectives To generate insight into the differences between utility measures EuroQol 5D (EQ-5D), Health Utilities Index Mark II (HUI2) and Mark III (HUI3) and their impact on the incremental cost-effectiveness ratio (ICER) for hearing aid fitting Methods Persons with hearing complaints completed EQ-5D, HUI2 and HUI3 at baseline and, when applicable, after hearing aid fitting. Practicality, construct validity, agreement, responsiveness and impact on the ICER were examined. Results All measures had high completion rates. HUI3 was capable of discriminating between clinically distinctive groups. Utility scores (n = 315) for EQ-5D UK and Dutch tariff (0.83; 0.86), HUI2 (0.77) and HUI3 (0.61) were significantly different, agreement was low to moderate. Change after hearing aid fitting (n = 70) for HUI2 (0.07) and HUI3 (0.12) was statistically significant, unlike the EQ-5D UK (0.01) and Dutch (0.00) tariff. ICERs varied from €647,209/QALY for the EQ-5D Dutch tariff to €15,811/QALY for HUI3. Conclusion Utility scores, utility gain and ICERs heavily depend on the measure that is used to elicit them. This study indicates HUI3 as the instrument of first choice when measuring utility in a population with hearing complaints, but emphasizes the importance of a clear notion of what constitutes utility with regard to economic analyses.     

The stability of utility scores: Test–retest reliability and the interpretation of utility scores in elective total hip arthroplasty

Quality of Life Research - Purposes: Are utility scores for hypothetical health states stable over time even when the health of the patient changes dramatically? Can investigators who use scores...     

Health state preference scores for children with permanent childhood hearing loss: a comparative analysis of the QWB and HUI3

PURPOSE: The aim of this study was to compare two preference-weighted, caregiver-reported measures of health-related quality of life for children with permanent childhood hearing loss to determine whether cost-effectiveness analysis applied to deaf and hard of hearing populations will provide similar answers based on the choice of instrument. METHODS: Caregivers of 103 children in Arkansas, USA, with documented hearing loss completed the Quality of Well-Being Scale (QWB) and the Health Utilities Index Mark 3 (HUI3) to describe the health status of their children. Audiology and other clinical measures were abstracted from medical records. Mean scores were compared overall and by degree of hearing loss. Linear regression was used to correlate preference scores with a four-frequency pure-tone average, cochlear implant status, and other factors. RESULTS: Mean preference scores for the QWB and HUI3 were similar (0.601 and 0.619, respectively) although the HUI3 demonstrated a wider range of values (-0.132 to 1.000) compared to the QWB (0.345-0.854) and was more sensitive to mild hearing loss. Both measures correlated with the pure-tone average, were negatively associated with comorbid conditions and positively associated with cochlear implant status. In the best fitting regression models, similar estimates for cochlear implant status and comorbid conditions were obtained from the two measures. CONCLUSIONS: Despite considerable differences in the HUI3 and the QWB scale, we found agreement between the two instruments at the mean, but clinically important differences across a number of measures. The two instruments are likely to yield different estimates of cost-effectiveness ratios, especially for interventions involving mild to moderate hearing loss.     

Sensitivity of EQ-5D-3L,HUI2, HUI3, and SF-6D to changes in speech reception and tinnitus associated with cochlear implantation

Quality of Life Research - There is concern that some generic preference-based measures (GPMs) of health-related quality of life may be insensitive to interventions that improve hearing....     

Evaluating quality-adjusted life years: estimation of the health utility index (HUI2) from the SF-36.

Quality-adjusted life years (QALYs) are well recognized as a valid measure for outcomes in cost-effectiveness analyses. A summary health utility score is necessary to evaluate QALYs. The objective of this study was to predict a summary utility score (represented by the Health Utility Index [HUI2]) from scores on the SF-36. METHODS: A structural equation framework was applied to longitudinal data collected from 1992 to 1995 on a sample of patients insured by Southem California Kaiser Permanente (N = 6921). An ordinary least squares (OLS) method was used to estimate the HUI2. RESULTS: The OLS model on cross-sectional data predicted 50.5% of the observed variance in HUI2 scores. Parameter estimates of all SF-36 components showed statistical significance at the P < 0.05 level. CONCLUSIONS: Results of this study provide a quantitative link between two important measures of health status. The present model can be used to estimate health utility summary scores in studies that have collected SF-36 data.