Roughly right or precisely wrong? Systematic review of quality-of-life weights elicited with the time trade-off method

Measuring Quality of Life in Diabetic Retinal Disease: A Narrative Review of Available Patient-Reported Outcome Measures

Topic

Several patient-reported outcome measures (PROMs) are available to measure health-related quality of life (HRQoL) in patients with late-stage clinical diabetic retinal diseases (DRDs). However, an understanding of the psychometric properties of PROMs is needed to assess how they could relate to severity levels of a revised DRD grading system. This narrative review assessed the available generic-, vision-, and DRD-related PROMs used in DRD research and highlights areas for improvement.

Clinical Relevance

Diabetic retinal disease is a common complication of diabetes and can lead to sight-threatening complications with a devastating effect on HRQoL.

Methods

The Quality of Life working group is one of 6 working groups organized for the DRD Staging System Update Effort, a project of the Juvenile Diabetes Research Foundation Mary Tyler Moore Vision Initiative. PubMed, Cochrane Library, Embase, and Google Scholar databases were searched using core keywords to retrieve ophthalmology-related review articles, randomized clinical trials, and prospective, observational, and cross-sectional studies in the English language. A detailed review of 12 PROMs (4 QoL questionnaires and 8 utilities) that met a minimum level of evidence (LOE) was conducted. The relevance of each PROM to DRD disease stage and Biomarker Qualification guidelines (Biomarkers, EndpointS, and other Tools) categories was also defined.

Results

The National Eye Institute 25-item Visual Function Questionnaire (NEI VFQ-25), Impact of vision impairment-computerized adaptive testing, and Diabetic Retinopathy and Macular Edema Computerized Adaptive Testing System had a LOE of II in detecting change due to late-stage DRD (diabetic macular edema), although several areas for improvement (e.g., psychometrics and generalizability) were identified. Other PROMs, particularly the utilities, had a LOE of III due to cross-sectional evidence in late-stage clinical DRD. Although the NEI VFQ-25 has been the most widely used PROM in late-stage DRD, more work is required to improve its multidimensional structure and other psychometric limitations. No PROM was deemed relevant for subclinical or early/mid-DRD.

Conclusion

This narrative review found that the most commonly used PROM is NEI VFQ-25, but none meets the ideal psychometric, responsiveness, and clinical setting digital administration requirements that could be included in an updated DRD staging system for diagnosis and monitoring of DRD progression.

Financial Disclosures

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Completing the time trade-off with respondents who are older, in poorer health or with an immigrant background in an EQ-5D-5L valuation study

OBJECTIVES

To determine the effects of age, immigrant background, and poor self-reported health in a general population sample on the probability of non-completion or slow completion of the time trade-off (TTO).

METHODS

We used data from an interrupted Norwegian EQ-5D-5L valuation study conducted between 2019 and 2020. All participants responded to background items, irrespective of completion. We used mixed effect logistic regression analysis to assess the effect of old age, poor health, and immigrant background on the probability of non-completion of the TTO, and, for those who completed the TTO, of slow completion times.

RESULTS

First experiences from a Norwegian valuation study were that 29 (5.5%) respondents failed to complete the TTO tasks. For those reporting age over 65 years, poor health, or an immigrant background, 12% failed to complete the TTO. Adjusted odds ratios for predictors of non-completion were statistically significant (age > 65 years, 8.3; EQ-VAS ≤ 50, 3.49; immigrant background, 4.56). Being over 65 years or with an immigrant background also predicted slow completion of both the introduction and TTO tasks.

CONCLUSIONS

High age, poor health, and immigrant status increased the risk of not being able to complete the TTO tasks, and of slow completion. Higher non-completion rates and increased completion times suggest that elements of the TTO may be demanding for some respondent groups, with possible implications for representativeness.

Self-esteem in patients with venous thromboembolism predicts time trade-off values for own health

Background

The time trade-off (TTO) is a commonly used preference based method to assess health related values used in health economic analyses. Surprisingly little is known about the factors influencing the TTO. Since self-esteem is a predictor for health status measurements, and health status affects the TTO, we studied the relation between self-esteem and TTO values.

Methods

Data of 128 patients treated with vitamin K antagonists for venous thromboembolism on Short Form-36 (SF-36), Rosenberg self-esteem and patient characteristics were collected. TTO values were obtained for ‘current health’ and three chronic health states related to thrombosis, in face-to-face interviews with patients. Regression analyses were performed with the TTO as dependent variable. Analyses were performed in two groups; the complete sample, and traders only. Selected predictors were entered in four blocks: socio-demographic factors, medical-clinical factors, health status, and self-esteem.

Results

In the complete sample (N = 128), bivariate regression analysis showed that self-esteem explained 14% of the variance in TTO values for current health (p < .000, N = 117). In traders, multivariate regression analysis showed a significant relationship between self-esteem and TTO values for current health. Self-esteem increased the variance explained (R²) by 8.8%, from 28.1 to 36.9%, (p = 0.01; N = 57). For hypothetical health states, the effect of self-esteem was weaker and mostly absent after controlling for selected variables.

Conclusions

In patients willing to trade-off time, higher self-esteem was associated with higher TTO values for own current health. Self-esteem explained an appreciable proportion of the variance in TTO values in traders. For hypothetical health states such associations were weak or absent.

Vignette-Based Utilities: Usefulness, Limitations, and Methodological Recommendations

Health technology assessment agencies often prefer that utilities used to calculate quality-adjusted life years in cost-utility analyses (CUAs) are derived using standardized methods, such as generic preference-based measures completed by patients in clinical trials. However, there are situations when no standardized approach is feasible or appropriate for a specific medical condition or treatment that must be represented in a CUA. When this occurs, vignette-based methods are often used to estimate utilities. A vignette (sometimes called a "scenario," "health state description," "health state vignette," or "health state") is a description of a health state that is valued in a preference elicitation task to obtain a utility estimate. This method is sometimes the only feasible way to estimate utilities representing a concept that is important for a CUA. Consequently, vignette-based studies continue to be conducted and published, with the resulting utilities used in economic models to inform decision making about healthcare resource allocation. Despite the potential impact of vignette-based utilities on medical decision making, there is no published guidance or review of this methodology. This article provides recommendations for researchers, health technology assessment reviewers, and policymakers who may be deciding whether to use vignette-based methods, designing a vignette study, using vignette-based utilities in a CUA, or evaluating a CUA that includes vignette-based utilities. Recommendations are provided on: (A) when to use vignette-based utilities, (B) methods for developing vignettes, (C) valuing vignettes, (D) use of vignette-based utilities in models, and (E) limitations of vignette methods.

Community perspectives on difference of sex development (DSD) diagnoses: A crowdsourced survey

INTRODUCTION AND OBJECTIVES

Differences of sex development (DSD) engender ethical, social and psychosexual complexities that can complicate medical decision-making. We performed a web-based pilot study to estimate the utility value of a DSD diagnosis and to identify community concerns regarding DSD management.

METHODS

A cross-sectional survey was posted on Amazon's Mechanical Turk, an online crowdsourcing platform. Respondents were ≥18y and were randomized to receive information on one of three common DSD conditions: Congenital Adrenal Hyperplasia (CAH), Mixed Gonadal Dysgenesis (MGD), and Partial Androgen Insensitivity Syndrome (PAIS). Time trade-off methodology was used to estimate utility values. Likert scale and statement-ranking questions were used to assess respondent perceptions.

RESULTS

Of 1,628 respondents, median age was 34y; most respondents were parents (59.1%), white (77.1%), and previously unfamiliar with DSD (60.4%). The median overall utility value was 0.70 (IQR 0.50-0.90), similar to moderately severe chronic health conditions. Utility estimates varied based on the DSD scenario presented (0.80 CAH vs. 0.70 MGD vs. 0.80 PAIS, p = 0.0006), respondent gender (p < 0.0001), race (p = 0.002), religion (p = 0.005), and prior knowledge of DSD (p < 0.0001). Reported concerns included gender identity (23.4%), urinary function (20.5%) and surgical complications (17.4%). Most (67.5%) supported early surgical intervention at 6-18 mo; 10.4% thought surgery should occur ≥18 y.

COMMENT

Limitations of this study include that survey participants were aware of the nature of the study, thus some respondents may have participated to skew the results. Given the nature of this pilot study, the representation of families with children with DSD within the study is severely limited given the rarity of DSDs. This means that their opinions may be diluted by the large sample size. However, because utility values are classically estimated according to community opinions, the utility data presented should be taken to reflect that of the specific sample studied and is not reflective of that of families with a vested interest in such cases.

CONCLUSIONS

Community-based respondents perceived that DSD conditions were associated with a reduction in utility values (0.70-0.80), on par with moderately severe chronic health conditions. Estimates varied based on respondents' gender, race, religion and prior knowledge of DSD. Gender identity was the most concerning aspect for respondents.

Anchoring bias in face-to-face Time-Trade-Off valuations of health states

OBJECTIVE

To test whether anchoring (a cognitive bias) occurs during face-to-face interviews to value health states by Time-Trade-Off.

METHODS

147 Colombian subjects (111 males, 36 females) valued five EQ-5D health states better than death during a face-to-face interview. Subjects were randomly assigned to two different starting points.

RESULTS

Shapiro-Wilk test discarded normality, while non-parametric tests, including Kolmogorov-Smirnov and Wilcoxon-Mann-Whitney, showed that anchoring was significant in four out of five health states. A higher starting point increased the elicited value by 15 %-188 %. The size of the anchoring effect was not uniform among health states.

CONCLUSION

Anchoring effects may bias face-to-face Time Trade-Off valuations. The size of the anchoring effect is relevant enough for health policy.

Valuing Treatments for Parkinson Disease Incorporating Process Utility: Performance of Best-Worst Scaling, Time Trade-Off, and Visual Analogue Scales

OBJECTIVE

The objective of this study was to compare treatment profiles including both health outcomes and process characteristics in Parkinson disease using best-worst scaling (BWS), time trade-off (TTO), and visual analogue scales (VAS).

METHODS

From the model comprising of seven attributes with three levels, six unique profiles were selected representing process-related factors and health outcomes in Parkinson disease. A Web-based survey (N = 613) was conducted in a general population to estimate process-related utilities using profile-based BWS (case 2), multiprofile-based BWS (case 3), TTO, and VAS. The rank order of the six profiles was compared, convergent validity among methods was assessed, and individual analysis focused on the differentiation between pairs of profiles with methods used.

RESULTS

The aggregated health-state utilities for the six treatment profiles were highly comparable for all methods and no rank reversals were identified. On the individual level, the convergent validity between all methods was strong; however, respondents differentiated less in the utility of closely related treatment profiles with a VAS or TTO than with BWS. For TTO and VAS, this resulted in nonsignificant differences in mean utilities for closely related treatment profiles.

CONCLUSIONS

This study suggests that all methods are equally able to measure process-related utility when the aim is to estimate the overall value of treatments. On an individual level, such as in shared decision making, BWS allows for better prioritization of treatment alternatives, especially if they are closely related. The decision-making problem and the need for explicit trade-off between attributes should determine the choice for a method.

Qualitative and Quantitative Analysis of Interviewer Help Answering the Time Tradeoff

OBJECTIVES

The time tradeoff (TTO) is an important method to directly obtain health utilities. Challenges of the TTO are, among others, "nontraders" and illogical answers. In TTO interviews, these challenges are resolved by the interviewer. In web-based TTOs, training procedures and logical checks are used based on the views of the researchers. As web-based TTOs will be used more often in the future, we investigated how respondents arrive at their ratings to determine the help they require.

METHODS

In 2 earlier studies performed by this research group, respondents valued 6 EQ-5D states on a TTO. Respondents were asked to think out loud, and all interviews were audiotaped. A random selection of these interviews were transcribed and double-coded by two independent raters, using a priori and inductive coding until saturation was reached. Based on the retrieved mistakes and comments, a list of frequently asked questions (FAQ) was developed.

RESULTS

In total, 91 interviews were coded. In all, 85% made at least 1 mistake, 41% made a misreading/miscalculation, 70% misunderstood the tradeoff, 27% misunderstood the EQ-5D dimensions, 29% misunderstood the scenario, 45% made a comment about the TTO, and 43% expressed frustration. More misunderstandings were reported in the Peeters study, which was performed in a realistic setting, whereas the van Osch study was conducted in a more ideal setting. Misunderstandings of the scenario were mosly reported by patients.

CONCLUSIONS

Almost all respondents need interviewer help. This may have implications for the validity of interviewer-based TTO elicitations when social acceptability bias is an issue or with explicit hypothesis and the interviewer is not blinded. The FAQ list can be used to standardize interviewer help or as a help function in a web-based TTO.

Introducing the composite time trade-off: a test of feasibility and face validity

INTRODUCTION

This study was designed to test the feasibility and face validity of the composite time trade-off (composite TTO), a new approach to TTO allowing for a more consistent elicitation of negative health state values.

METHODS

The new instrument combines a conventional TTO to elicit values for states regarded better than dead and a lead-time TTO for states worse than dead.

RESULTS

A total of 121 participants completed the composite TTO for ten EQ-5D-5L health states. Mean values ranged from -0.104 for health state 53555 to 0.946 for 21111. The instructions were clear to 98 % of the respondents, and 95 % found the task easy to understand, indicating feasibility. Further, the average number of steps taken in the iteration procedure to achieve the point of indifference in the TTO and the average duration of each task were indicative of a deliberate cognitive process.

CONCLUSION

Face validity was confirmed by the high mean values for the mild health states (>0.90) and low mean values for the severe states (<0.42). In conclusion, this study demonstrates the feasibility and face validity of the composite TTO in a face-to-face standardized computer-assisted interview setting.

Time trade-off: one methodology, different methods

There is no scientific consensus on the optimal specification of the time trade-off (TTO) task. As a consequence, studies using TTO to value health states may share the core element of trading length of life for quality of life, but can differ considerably on many other elements. While this pluriformity in specifications advances the understanding of TTO from a methodological point of view, it also results in incomparable health state values. Health state values are applied in health technology assessments, and in that context comparability of information is desired. In this article, we discuss several alternative specifications of TTO presented in the literature. The defining elements of these specifications are identified as being either methodological, procedural or analytical in nature. Where possible, it is indicated how these elements affect health state values (i.e., upward or downward). Finally, a checklist for TTO studies is presented, which incorporates a list of choices to be made by researchers who wish to perform a TTO task. Such a checklist enables other researchers to align methodologies in order to enhance the comparability of health state values.

Cost-effectiveness of angiotensin-converting enzyme inhibitors for the prevention of diabetic nephropathy in The Netherlands--a Markov model

OBJECTIVE

Type 2 diabetes is the main cause of end-stage renal disease (ESRD) in Europe and the USA. Angiotensin-converting enzyme (ACE) inhibitors have a potential to slow down the progression of renal disease and therefore provide a renal-protective effect. The aim of our study was to assess the most cost-effective time to start an ACE inhibitor (or an angiotensin II receptor blocker [ARB] if coughing as a side effect occurs) in patients with newly diagnosed type 2 diabetes in The Netherlands.

METHODS

A lifetime Markov decision model with simulated 50-year-old patients with newly diagnosed diabetes mellitus was developed using published data on costs and health outcomes and simulating the progression of renal disease. A health insurance perspective was adopted. Three strategies were compared: treating all patients at the time of diagnosing type 2 diabetes, screening for microalbuminuria, and screening for macroalbuminuria.

RESULTS

In the base-case analysis, the treat-all strategy is associated with the lowest costs and highest benefit and therefore dominates screening both for macroalbuminuria and microalbuminuria. A multivariate sensitivity analysis shows that the probability of savings is 70%.

CONCLUSIONS

In The Netherlands for patients with type 2 diabetes prescription of an ACE inhibitor immediately after diagnosis should be considered if they do not have contraindications. An ARB should be considered for those patients developing a dry cough under ACE inhibitor therapy. The potential for cost savings would be even larger if the prevention of cardiovascular events were considered.

A model to predict the cost-effectiveness of disease management programs

High costs and deficits in the care of patients with chronic diseases have triggered numerous programs to improve the quality and efficiency of treatment of chronic diseases. Decision makers need to estimate the impact of a disease management program (DMP) on long-term costs and cost-effectiveness in order to decide which programs to introduce. This prediction, however, requires formalizing the relations between a variety of variables. The purpose of this paper is to formalize these relations and develop a model that enhances the quality of predictions of the costs and cost-effectiveness of a DMP. The model's cost function is able to portray a reduction both of treatment overuse and underuse by improving both physician and patient compliance. The model's applicability is demonstrated by a simulated DMP for patients with hypertension. The application example shows that implementation costs may have a larger financial impact than downstream costs.

Cost-effectiveness of angiotensin-converting enzyme inhibitors and angiotensin II receptor blockers in newly diagnosed type 2 diabetes in Germany

OBJECTIVES

Type 2 diabetes is the main cause of end-stage renal disease in Europe and the United States. Angiotensin-converting enzyme (ACE) inhibitors slow down the progression of renal disease and, therefore, provide a renal-protective effect. The aim of this study was to assess the most cost-effective time to start an ACE inhibitor (or an angiotensin II receptor blocker in the event of cough) in patients with type 2 diabetes in Germany.

METHODS

Three strategies were compared: treating all patients at the time of diagnosing type 2 diabetes, screening for microalbuminuria, and screening for macroalbuminuria. A lifetime Markov decision model with simulated 50-year-old patients with newly diagnosed diabetes mellitus was developed using published data on costs and health outcomes and simulating the progression of renal disease. A statutory health insurance perspective was adopted.

RESULTS

In the base-case analysis, the treat-all strategy is associated with the lowest costs and highest benefit and, therefore, dominates screening both for macroalbuminuria and microalbuminuria. A multivariate sensitivity analysis shows that the probability of savings is 89 percent.

CONCLUSIONS

Patients with type 2 diabetes should receive an ACE inhibitor immediately after diagnosis if they do not have contraindications. The potential for cost savings would be even larger if the prevention of cardiovascular events were considered.

Protocols for time tradeoff valuations of health states worse than dead: a literature review

BACKGROUND

The time tradeoff (TTO) method of preference elicitation allows respondents to value a state as worse than dead, generally either through the Torrance protocol or the Measurement and Valuation of Health (MVH) protocol. Both of these protocols have significant weaknesses: Valuations for states worse than dead (SWD) are elicited through procedures different from those for states better than dead (SBD), and negative values can be extremely negative.

PURPOSE

To provide an account of the different TTO designs for SWD, to identify any alternatives to the MVH and Torrance approaches, and to consider the merits of the approaches identified.

METHODS

Medline was searched to identify all health state valuation studies employing TTO. The ways in which SWD were handled were recorded. Furthermore, to ensure that there are no unpublished but feasible TTO variants, the authors developed a theoretical framework for identifying all potential variants.

RESULTS

The search produced 593 hits, of which 218 were excluded. Of the remaining 375 articles, only 29 included protocols for SWD. Of these, 23 used the MVH protocol and 4 used the Torrance protocol. The other 2 used 1 protocol for SBD and SWD, one making use of lead time and the other using a 2-stage procedure with chaining. The systematic framework did not identify any alternatives to the Torrance and MVH protocols that were superior to the lead time approach.

CONCLUSIONS

Few studies elicit values for SWD. The lead time approach is a potential alternative to the Torrance and MVH protocols. Key words: QALY; states worse than dead; health state valuation; preference elicitation.

Some considerations for the communication of results of air pollution health effects tracking

Communicating effectively and efficiently on air quality and its health impacts is an important but difficult and complex task. It requires careful consideration of the audience one wants to reach, the messages one is trying to present, the venue through which the message will be delivered. The audience, context, technique, and content factors may affect how well it is heard and how appropriately it is interpreted. In this short paper, I describe many of these concerns and provide some suggestions for how best to address them. However, since every audience differs in goals, characteristics, and nature, what is most important is implementing an effective communications program. This program should include frequent two-way communication, repeated and on-going evaluation of how well the audience understands the messages, and consideration of how to improve the delivery.

The influence of subjective life expectancy on health state valuations using a 10 year TTO

AIM

To investigate if subjective life expectancy (SLE) impacts the willingness to trade-off (WTT) and the number of years traded-off in a 10-years time trade-off (TTO) exercise to obtain health state valuations.

METHODS

An Internet-based questionnaire was administered in a sample representative for the Dutch general public. Next to basic demographic characteristics and SLE, respondents were asked to perform three TTO exercises. The following EQ-5D health states were included 21211 (TTO1), 22221 (TTO2) and 33312 (TTO3). The WTT was studied using a probit regression model. The number of years traded-off was investigated using a generalized negative binomial regression model. The independent variables used in both models were age, gender, quality of life, education, the difference between age and expected age of death (SLE), and a variable indicating whether the SLE was less than 10 years (SLE<10).

RESULTS

Three hundred and thirty nine respondents completed the questionnaire. The mean utility scores were 0.96 (TTO1), 0.94 (TTO2) and 0.79 (TTO3). The probit model showed that SLE was the only variable with a significant influence on WTT. The gnbreg showed that the number of years traded-off was also significantly influenced by SLE. In addition, age and education significantly influenced the number of years traded-off.

CONCLUSION

The WTT years and the number of years traded-off were both influenced by SLE in 10-years TTO exercises. Reducing remaining life expectancy to 10 years in a TTO may thus increase loss aversion and, especially in respondents losing relatively many expected life years, diminish WTT and the amount of time traded off.

Breaking the silence: exploring the potential effects of explicit instructions on incorporating income and leisure in TTO exercises

OBJECTIVES

An underexplored question in the debate on incorporating productivity costs as costs or effects in a cost-effectiveness (CE) analysis is whether people include effects of ill health on income in health state valuations (HSV). The same holds for the actual inclusion in HSV of the effects of ill health on leisure. This study aims to test whether respondents to HSV using time trade-off (TTO) questions include income and leisure effects without instructions. Moreover, it tests the consequences of explicit instructions to include or exclude income effects.

METHODS

Three questionnaires were administered among the general public. Respondents were asked to value three distinct EuroQol descriptive system health states using TTO. In version 1, respondents were asked afterwards whether they included income effects. In versions 2 and 3, respondents were instructed upfront to include or exclude income effects. They were furthermore asked whether they included leisure effects.

RESULTS

A total of 222 respondents completed the questionnaire. In version 1, 64% of the respondents spontaneously included income effects, not resulting in differences in mean valuations. In versions 2 and 3, 88% included leisure time, resulting in a significantly lower TTO value in one health state. With explicit instructions, respondents instructed to include income gave lower HSV for the worst health state presented.

CONCLUSIONS

Respondents in our sample did not consistently include income effects and leisure effects. Including income effects only had (some) effect on TTO valuations after an explicit instruction. If these results are confirmed in future research, this implies that income effects may be best captured on the cost-side of the CE ratio. Spontaneous inclusion or exclusion of leisure time appeared to be more influential.

Utility assessment in patients with mental disorders: validity and discriminative ability of the time trade-off method

BACKGROUND

Preference-based health-state values, also referred to as utility scores, are considered an important measure of outcome in the evaluation of healthcare. A common approach to elicit utility scores is the use of the time trade-off (TTO) method; however, the data on TTO utility scores in patients with mental disorders are scarce.

OBJECTIVE

To analyse the TTO method in patients with mental disorders in terms of discriminative ability, validity and the refusal to trade life time (zero trade).

METHODS

In patients with affective (n = 172), schizophrenia spectrum (n = 166) and alcohol-related (n = 160) mental disorders, TTO utilities were administered through a standardized interview. Measures of quality of life (QOL) EQ-5D, WHOQOL-BREF, subjective (SCL-90R) and objective (CGI-S) psychopathology, and functioning (GAF, GARF, SOFAS, HoNOS) provided comparison. Discriminative ability was analysed by assessing frequency distributions of TTO utilities. Validity was analysed by assessing the correlation of TTO utilities with all other scores. The association of a patient's QOL, sociodemographic and disease-related variables with zero trade was analysed by logistic regression.

RESULTS

Of patients with affective/schizophrenic/alcohol-related mental disorders, 153/143/145 (89/86/91%), respectively, completed the TTO elicitation; 29/43/28% of the respondents were zero traders. The mean TTO utility was 0.66/0.75/0.61 and the median was 0.85/0.95/0.75. TTO utility scores discriminated well among more impaired mental health states, but discrimination was limited among less impaired health states. In patients with affective and alcohol-related mental disorders, TTO utility scores were significantly correlated (mostly moderate: 0.3 < r < 0.5) with all other scores. However, in schizophrenic patients, TTO utility scores were only a little correlated with other subjective measures and not correlated with objective measures. QOL was significantly associated with zero trade; the influence of the other variables on zero trade was negligible.

CONCLUSIONS

TTO utility scores in patients with affective or alcohol-related mental disorders were reasonably valid, but discriminative ability was compromised by a ceiling effect due to zero trade. In schizophrenic patients, validity of TTO utility scores was not demonstrated.

Utility of health states in chronic kidney disease: a structured review of the literature

PURPOSE

To document published utilities for health states associated with Chronic Kidney Disease (CKD) and End Stage Renal Disease (ESRD) and determine the most appropriate values for use in economic models to evaluate renal treatments in the UK.

METHODS

A structured literature review was conducted (MEDLINE, EMBASE, NHS EED and HTA) in order to identify relevant articles published between January 1990 and January 2006. In addition searches were conducted on websites of Health Technology Assessment (HTA) organizations and the Cost Effectiveness Analysis Registry. Articles were reviewed and those not containing utilities excluded. Results were assessed on the quality of the elicitation studies and their relevance to the UK HTA environment.

RESULTS

Thirty-five studies satisfied the inclusion criteria. Most studies were conducted in Canada (13), the US (10) and the Netherlands (4). Utilities were identified for all/most of the necessary states, but scores for individual states differed widely between studies and very few studies met the quality criteria. The majority of studies used the time trade-off (23) and standard gamble (11) to elicit utilities, while only six used EQ-5D. Seven studies provided community preferences. Two studies were judged to be directly relevant to economic evaluations in the UK.

CONCLUSIONS

Many studies have estimated utilities in ESRD patients, but only a few have estimated utilities based upon public preferences. Further empirical research is needed to produce more reliable utilities for economic modelling in the UK, especially in chronic kidney disease patients who do not require dialysis.

Why people refuse to make tradeoffs in person tradeoff elicitations: a matter of perspective?

OBJECTIVE

Person tradeoff (PTO) elicitations assess people's values for health states by asking them to compare the value of treatment programs. For example, people might be asked how many patients need to be cured of health condition X to equal the benefit of curing 100 people of condition Y. However, when faced with PTO elicitations, people frequently refuse to make quantifiable tradeoffs, exhibiting 2 kinds of refusals: 1) They say that 2 treatment programs have equal value, that curing 100 of X is just as good as curing 100 of Y, even if X is a less serious condition than Y, or 2) they say that the 2 programs are incomparable, that millions of people need to be cured of X to be as good as curing 100 of Y. The authors explore whether people would be more willing to make tradeoffs if the focus was changed from trading off groups of patients to choosing the best decision or evaluating treatment benefits.

DESIGN

. Two randomized trials used diverse samples (N=2400) via the Internet to test for the effect of perspective on refusal rates. The authors predicted that perspectives that removed people from decision-making roles would increase their willingness make tradeoffs.

RESULTS

Contrary to expectations, refusal rates increased when people were removed from decision-making roles. In fact, the more pressure put on people to make a decision, the less likely they were to refuse to make tradeoffs.

CONCLUSION

To reduce PTO refusals, it is best to adopt a decision-maker perspective.

A national hypertension treatment program in Germany and its estimated impact on costs, life expectancy, and cost-effectiveness

Almost 15 million Germans may suffer from untreated hypertension. The purpose of this paper is to estimate the cost-effectiveness of a national hypertension treatment program compared to no program. A Markov decision model from the perspective of the statutory health insurance (SHI) was built. All data were taken from secondary sources. The target population consists of hypertensive male and female patients at high or low risk for cardiovascular events at different age groups (40-49, 50-59, and 60-69 years). The analysis shows fairly moderate cost-effectiveness ratios even for low-risk groups (less than 12,000 euros per life year gained). In women at high risk antihypertensive treatment even leads to savings. This suggests that a national hypertension treatment program provides good value for money. Given the considerable costs of the program itself, any savings from avoiding long-term consequences of hypertension are likely to be offset, however.

Lessons from trial-based cost-effectiveness analyses of mental health interventions: why uncertainty about the outcome, estimate and willingness to pay matters

The principal aim of this article is to share lessons learned by the authors while conducting economic evaluations, using clinical trial data, of mental health interventions. These lessons are quite general and have clear relevance for pharmacoeconomic studies. In addition, we explore how net benefit regression can be used to enhance consideration of key issues when conducting an economic evaluation based on clinical trial data. The first study we discuss found that cost-effectiveness results varied markedly based on the choice of both the patient outcome and the willingness to pay for more of that outcome. The importance of willingness to pay was also highlighted in the results from the second study. Even with a set willingness-to-pay value, most of the time the probability that the new treatment was cost effective was not 100%. In the third study, the cost effectiveness of the new treatment varied by patient characteristics. These observations have important implications for pharmacoeconomic studies. Namely, analysts must carefully consider choice of patient outcome, willingness to pay, patient heterogeneity and the statistical uncertainty inherent in the data. Net benefit regression is a useful technique for exploring these crucial issues when undertaking an economic evaluation using patient-level data on both costs and effects.

A guide to economic evaluation: methods for cost-effectiveness analysis of person-level data

The authors introduce economic evaluation with particular attention to cost-effectiveness analysis. They begin by establishing why health care decisions should be guided by economics. They then explore different types of economic evaluations. To illustrate how to conduct and evaluate a cost-effectiveness analysis, a hypothetical study about the treatment of posttraumatic stress disorder with psychotherapy versus pharmacotherapy is considered. The authors conclude with recommendations for increasing the strength and relevance of economic evaluations.

Health-related quality of life and estimates of utility in chronic kidney disease

BACKGROUND

Health-related quality of life and estimates of utility have been carefully evaluated in persons with end-stage renal disease. Fewer studies have examined these parameters in persons with chronic kidney disease (CKD).

METHODS

To determine the relations among kidney function, health-related quality of life, and estimates of utility, we administered the Kidney Disease Quality of Life Short Form 36 (KDQOL-36), Health Utilities Index (HUI)-3, and Time Trade-off (TTO) questionnaires to 205 persons with CKD. Persons with CKD stages 4 and 5 (estimated GFR <30 mL/min/1.73 m2, N= 115) were tested two to eight times over the subsequent two years. The relations among estimated glomerular filtration rate (eGFR), and changes in health-related quality of life and utility over time were estimated using mixed effect regression models. Models were adjusted for age, sex, race, and diabetes.

RESULTS

Mean scores on the KDQOL-36 generic components, HUI-3, and TTO suggested considerable loss of function and well-being in CKD relative to population norms. On cross-sectional analysis, lower levels of kidney function were associated with significantly lower scores on the SF-12 Physical Health Composite (P= 0.002), the Burden of Kidney Disease subscale (P < 0.0001), and the Effects of Kidney Disease subscale (P < 0.0001) of the KDQOL-36trade mark. Kidney function was significantly associated with the TTO (P= 0.008) and global HUI-3 utility (P= 0.016) although these associations were attenuated after adjustment for diabetes. A decline in eGFR was associated with a significant increase in the reported Burden of Kidney Disease (5.0 point change per year per mL/min/1.73 m2 decline in eGFR) and with marginally significant changes in the Dexterity and Pain attributes of the HUI-3. Mean HUI-3 scores for persons with CKD stages 4 and 5, absent dialysis, were in the range previously reported for persons with stroke and severe peripheral vascular disease.

CONCLUSION

Health-related quality of life and estimates of utility are distressingly low in persons with CKD. Self-reported outcomes should be considered when evaluating health policy decisions that affect this population.

QALYs: are they helpful to decision makers?

The QALY is the product of life expectancy (estimated in years) and its quality over that time (estimated in utilities or QOL units). It theoretically enables direct comparison of the costs of obtaining different health outcomes through cost utility analysis (CUA). In this review, we argue that, at present, the problems related to the use of utilities preclude the use of cost per QALY as a major determinant of policy decisions on the acquisition and use of health technologies. Those who use CUA can be divided into (i) those who inform the process of decision making through CUA and (ii) those who make the decisions. The former have no direct budgetary responsibility for the decisions that are taken, while the decision makers must pay for those decisions from their budgets. Use of CUA rests on the assumption that all QALYs are of equivalent value in the eyes of society. However, the value accorded to them varies with circumstances. The utilities or QOL indices required to compute QALYs can be measured in different ways, which give different answers, and have been shown to be unreliable. Thus, the QALY is not sufficiently accurate or reliable to be used by decision makers as a basis for comparison of the costs of different technologies. Until the theoretical and practical problems of determining health preferences are resolved and the methods of their measurement are standardised, it is necessary to estimate the cost effectiveness of health interventions by relating their cost to their primary health outcomes.

An introduction to economic evaluation: what's in a name?

OBJECTIVE

This paper describes the main types of economic evaluation techniques.

METHOD

To examine the strengths and limitations of different types of economic evaluations, we used a hypothetical example to review the reasoning underlying each method and to illustrate when it is appropriate to use each method.

RESULTS

The choice of economic evaluation method reflects a decision about what should represent "success" and how success should be valued. Measures of benefit and cost must be considered systematically and simultaneously. Claiming that a new treatment is cost-effective requires making a value judgment based on the personal beliefs of the claimant. Even when cost and effect data are objective, a verdict of cost-effective is subjective. The conclusions of an economic study can change significantly, depending on which patient outcome is used to measure success.

CONCLUSIONS

Clinicians must be sure that important patient outcomes are not excluded from economic evaluations. Economic evaluation is a process designed to produce an estimate rather than a decision. New treatment can be more costly and still be cost-effective (if the extra benefit is valued more than the extra cost to produce it). However, since economic evaluation does not explicitly consider a decision maker's available budget, a new treatment can be deemed cost-effective but too expensive to approve.

Are QALYs based on time trade-off comparable?--A systematic review of TTO methodologies

A wide range of methods is used to elicit quality-of-life weights of different health states to generate 'Quality-adjusted life years' (QALYs). The comparability between different types of health outcomes at a numerical level is the main advantage of using a 'common currency for health' such as the QALY. It has been warned that results of different methods and perspectives should not be directly compared in QALY league tables. But do we know that QALYs are comparable if they are based on the same method and perspective?The Time trade-off (TTO) consists in a hypothetical trade-off between living shorter and living healthier. We performed a literature review of the TTO methodology used to elicit quality-of-life weights for own, current health. Fifty-six journal articles, with quality-of-life weights assigned to 102 diagnostic groups were included. We found extensive differences in how the TTO question was asked. The time frame varied from 1 month to 30 years, and was not reported for one-fourth of the weights. The samples in which the quality-of-life weights were elicited were generally small with a median size of 53 respondents. Comprehensive inclusion criteria were given for half the diagnostic groups. Co-morbidity was described in less than one-tenth of the groups of respondents. For two-thirds of the quality-of-life weights, there was no discussion of the influence of other factors, such as age, sex, employment and children. The different methodological approaches did not influence the TTO weights in a predictable or clear pattern. Whether or not it is possible to standardise the TTO method and the sampling procedure, and whether or not the TTO will then give valid quality-of-life weights, remains an open question.This review of the TTO elicited on own behalf, shows that limiting cost-utility analysis to include only quality life weights from one method and one perspective is not enough to ensure that QALYs are comparable.

Can the value choices in DALYs influence global priority-setting?

The "disability adjusted life years" (DALYs) are increasingly used as a tool for decision-making and for describing the distribution of the Global Burden of Disease. The "DALY" combines information about mortality and morbidity, with several value choices such as disability weighting, age-weighting and discounting. These value choices imply that life years are assigned different value, depending on the age and the health state they are in. How robust is the distribution of DALYs to changes in these value choices, and are the choices transparent at the point of use? We calculated the burden attributed to "developmental disability due to malnutrition" and "major depression" with alternative value choices in a simple sensitivity analysis. In particular, we explored the relation between disability weight, health state description and incidence rate. The formulae and information needed was found in the World Health Organisation (WHO) publications using DALYs, and in a survey among international health workers. We found that alternative age-weights, disability weights and discount rate led to an inversion in the ranking of the burden of the two conditions. The DALY loss attributed to "developmental disability due to malnutrition" increased from 14 to 90%, while that of "major depression" sunk from 86 to 10%. The value choices currently used, tend at underestimating the disease burden attributed to young populations and to communicable diseases and this goes against the renewed efforts of the WHO of targeting diseases that are typical of poor populations. While the value choices may be changed, lack of transparency is a more profound problem. At the point of use, the number of DALYs attributed to a condition cannot be fully disaggregated. Hence, one cannot know which part of a DALY loss reflects the age group affected, the prevalence, the mortality rates, the disability weight assigned to it, or to how the condition has been defined. A more transparent and useful approach, we believe, would be to present the years lost due to a disease, and the years lived with a disease separately, without disability weights, age-weights and discounting. This would keep the best of the DALY approach and come closer to the aim of disentangling science from advocacy.