The Time-trade-off Research Articles

Sample restrictions and the elicitation of a constant willingness to pay per quality adjusted life year.

It is well established that the underlying theoretical assumptions needed to obtain a constant proportional trade-off between a quality adjusted life year (QALY) and willingness to pay (WTP) are restrictive and often empirically violated. In this paper, we set out to investigate whether the proportionality conditions (in terms of scope insensitivity and severity independence) can be satisfied when data is restricted to include only respondents who pass certain consistency criteria. We hypothesize that the more we restrict the data, the better the compliance with the requirement of constant proportional trade-off between WTP and QALY. We revisit the Danish data from the European Value of a QALY survey eliciting individual WTP for a QALY (WTP-Q). Using a "chained approach" respondents were first asked to value a specified health state using the standard gamble (SG) or the time-trade-off (TTO) approach and subsequently asked their WTP for QALY gains of 0.05 and 0.1 (tailored according to the respondent's SG/TTO valuation). Analyzing the impact of the different exclusion criteria on the two proportionality conditions, we find strong evidence against a constant WTP-Q. Restricting our data to include only respondents who pass the most stringent consistency criteria does not impact on the performance of the proportionality conditions for WTP-Q.

A comparison of European, Polish, Slovenian and British EQ-5D-3L value sets using a Hungarian sample of 18 chronic diseases

BackgroundIn the Central and Eastern European region, the British EQ-5D-3L value set is used commonly in quality of life (QoL) studies. Only Poland and Slovenia have country-specific weights. Our study aimed to investigate the impact of value set choice on the evaluation of 18 chronic conditions in Hungary.MethodsPatients’ EQ-5D-3L index scores were calculated using the VAS-based Slovenian and European and the time-trade-off-based Polish and British value sets. We performed pairwise comparisons of mean index values by dimensions, diagnoses and age groups. We evaluated disease burden by comparing index values matched by age and gender in each condition with those of the general population of the CEE region in all four value sets.ResultsAltogether, 2421 patients (55% female) were included in our sample with the average age of 55.87 years (SD = 17.75). The average Slovenian, European, Polish and British EQ-5D-3L scores were 0.598 (SD = 0.279), 0.661 (SD = 0.257), 0.770 (SD = 0.261) and 0.644 (SD = 0.279), respectively. We found highly significant differences in most diagnoses, with the greatest difference between the Polish and Slovenian index values in Parkinson’s disease (0.265). Systematic pairwise comparison across all conditions and value sets revealed greatest differences between the time-trade-off (TTO) and VAS-based value sets as well as varying sensitivity of the disease burden evaluations of chronic disease conditions to the choice of value sets.ConclusionsOur results suggest that the choice of value set largely influences the health state utility results in chronic diseases, and might have a significant impact on health policy decisions.

Crowdsourcing utility estimation for spina bifida in the general population.

Cost-utility analyses (CUA) are useful when the treatment conditions depend on patient preferences that are in turn dependent on health state utility value. Spina bifida (SB) is an example of such a preference-sensitive condition. Historically, the SB utility value for CUA has been gathered via a traditional face-to-face interview. However, due to funding and time constrains, utility estimation via online crowdsourcing has recently gained popularity. Our aim was to estimate the utility value for a generic SB health state using a validated online tool. A cross-sectional survey of American adults was conducted using the time-trade-off (TTO) method. Participants were recruited from an online crowdsourcing interface, Amazon's Mechanical Turk (mTurk). Demographic information and prior knowledge of SB were assessed. Respondents were provided a written passage and an online video explaining SB and its potential associated comorbidities. Participants were queried on hypothetical ascending time-trades from a child-parent dyad perspective to determine the utility of a SB health state in an affected 6-year-old child. Respondents were also asked to indicate the percentage of time traded from their life in relation to their child's. Utility estimates were then calculated and compared using bivariate and multivariate analyses. We obtained 503 responses (85% response rate). Mean respondent age was 34 (± 11); 247 (49%) were female; 386 (77%) were white; 189 (38%) were married, and 234 (46%) had children. Mean proportion of longevity traded by participants in the dyadic interaction was 66% (± 27) from the parent's life. Only 51 respondents (9%) reported having "ample" prior knowledge of SB; 8 respondents (0.02%) had SB themselves. Few others had previous experience with SB or myelomeningocele either in a child (4, 1%), or friend/relative (28, 5%). Compared with a perfect health state of 1.0, we found mean utilities of 0.85 (±0.20) for SB. Utility estimation for SB is feasible through crowdsourcing, and the resultant values are similar to previous estimates using traditional techniques. Subjects view the SB health state to be inferior to perfect health.

Preferences for Route of Administration, Frequency and Location – A Time-Trade-Off Study in the United Kingdom General Population

The objective of this study was to investigate preferences from the UK general population for route, frequency and location of treatment administration, independent of disease area. We developed eight health states varying the route of administration (subcutaneous injection/intravenous infusion), frequency (every 1/2/4/8/12 weeks), and location (hospital/home) to correspond with treatment regimens for a number of commonly used biologic compounds. The time-trade-off (TTO) method was applied to elicit utility values associated with each health state. Respondents were repeatedly asked to ‘trade off’ a portion of their remaining lifespan for perfect health until a point of indifference was found. 1,645 adult respondents (≥18 years old) from the United Kingdom general population who were recruited through a representative internet-based survey panel completed the questionnaire. A utility value was assigned to each health state based on each individual’s response, derived from the midpoint of the indifference interval. Respondents preferred less frequent administration both for subcutaneous injections (weekly subcutaneous injections at home: 0.861; bi-weekly: 0.861; 8-weekly: 0.878; 12-weekly: 0.879) and infusions (infusions at the hospital 4-weekly: 0.836; 8-weekly: 0.849). Additionally, respondents prefer subcutaneous injections at home rather than at the hospital (subcutaneous injections every 12 weeks at the hospital: 0.873; at home: 0.879) and subcutaneous injections to infusions (treatment every 8 weeks at the hospital, infusion: 0.849; subcutaneous injection: 0.860). Receiving a subcutaneous injection at home every 12 weeks was preferred over all other health states (however not significantly for subcutaneous injection at home every 8 weeks). Route, frequency and location of administration matter for members of the general public as it has an impact on convenience. The best health state is receiving a subcutaneous injection every 12 weeks at home, showing that more convenient treatment regimens are associated with higher utility values.

"Back to the future": Influence of beliefs regarding the future on TTO answers.

BackgroundA common approach to obtain health state valuations is the time-tradeoff (TTO) method. Much remains unknown regarding the influence of responder characteristics on TTO answers. The objective of this study is to increase understanding of the influence that beliefs regarding future health and death, as well as desires to witness certain life events, have on respondents’ health state valuations.MethodsAn online survey was designed, including three TTO questions using a 10 year timeframe. Moreover, respondents completed demographic questions, the Health-Risk Attitude Scale (HRAS), the Expectations Regarding Aging (ERA) questionnaire, questions about beliefs regarding future health (i.e. life expectancy) and death (i.e. fear of death, belief in life after death and opinion about euthanasia), and about important life events taking place within the TTO timeframe. Regression analyses were performed in order to assess the influence of these different variables.ResultsOne thousand sixty-seven respondents were included in the analyses. The following variables were significantly associated with years traded off: ERA mental health (decrease), ERA physical health (increase), HRAS (increase), support for euthanasia (increase), fear of death (decrease) and consideration of an important life event (decrease). The explained variance of the final model was low (0.08).ConclusionTTO responses may be influenced by considerations of future health, including life events and attitudes regarding health risks and death. Further investigation of TTO responses remains warranted.Electronic supplementary materialThe online version of this article (doi:10.1186/s12955-015-0402-6) contains supplementary material, which is available to authorized users.

Elicitation of health state utilities associated with varying severities of flares in Systemic Lupus Erythematosus.

BackgroundSystemic Lupus Erythematosus (SLE) is characterised by fluctuating periods of minimal disease activity and ‘flare’. Flare is an important outcome variable impacting the disease burden associated with SLE. The objective of this study was to obtain population-based utility values for varying severities of flare to measure the impact on health-related quality of life (HRQoL) in Australia, Canada, France, Japan, Spain and the UK.MethodsSix health states (HS) for varying severities of flare were developed based on literature, patient blogs, and interviews with patients (n = 12), rheumatologists (n = 7) and nurses (n = 2). HS were validated by independent clinical experts (n = 6) and pilot interviews (n = 10, UK). HS were evaluated using the time-trade-off (TTO) method during face-to-face interviews with a minimum representative sample (n = 100) of the general population, per-country. Visual Analog Scale (VAS) scores were obtained to validate TTO scores. TTO scores were converted into utility values.ResultsThe highest mean TTO utility scores were observed for the anchor HS (minimal disease activity) across all countries; means ranged from 0.66 in Japan to 0.82 in UK. All flare HS were associated with a disutility compared with the anchor HS (p < 0.001), means ranged across countries: mild flare HS: 0.55–0.71, moderate flare HS: 0.38–0.53, severe renal flare HS: 0.33–0.45, severe central nervous system (CNS) flare HS: 0.30–0.45 and severe generalised flare HS: 0.19–0.33. Mean VAS scores followed the same trend.ConclusionsThese results show increasing severity of flare has a detrimental impact on HRQoL. The severe generalised flare HS received the lowest mean utility score suggesting that the perceived day-to-day impact of a severe generalised flare was greater than a severe CNS or severe renal flare. This is, to the best of our knowledge, the first utility study to assess varying severities of flare in SLE across six different countries.

Estimating utility values for vesicoureteral reflux in the general public using an online tool

IntroductionCost-utility analyses are useful to study conditions without a widely accepted treatment algorithm; in pediatric urology, one such condition is vesicoureteral reflux (VUR). A necessary component of cost-utility analyses is to accurately calculate the “utility”, a numerical surrogate of quality of life, for various health states. Our aims were to determine utility values for representative VUR health states and to verify the feasibility of a novel online platform for utility elicitation in order to reduce the time and expense of such analyses. MethodsA cross-sectional survey of American adults was conducted using the time-trade-off (TTO) method. Respondents were recruited from an online work interface, Amazon's Mechanical Turk (MTurk). Four annualized VUR health states were assessed: VUR treated with/without continuous antibiotic prophylaxis (CAP) and with/without associated febrile urinary tract infection (UTI). A 6-week post-operative scenario following open ureteroneocystostomy was also assessed. ResultsWe received 278 survey responses (70% response rate). The respondents were largely between the ages of 25 and 44 (59%), female (60%), and Caucasian (76%). Thirty-seven percent had a college degree, and 44% were parents. Compared with a perfect health state of 1.0, we found mean utilities of 0.87 for VUR, regardless of whether CAP was used or whether UTI was present (p = 0.9). The immediate post-operative period following ureteroneocystostomy garnered an annualized utility of 0.94. ConclusionsOur data suggest that MTurk-based utility assessment is feasible, and that subjects view the VUR health state as only slightly inferior to perfect health. This includes VUR health states incorporating CAP and febrile UTI.

PRM45 Utility Estimation for Visual Acuity Health States: An Original and Pragmatic Approach to Transpose Published Evidence Into a More Flexible Estimation

The NICE reference case stipulates cost-utility analysis as the preferred form of economic evaluation, with health effects expressed in QALYs and health states valued using a validated choice-based method such as the time-trade-off (TTO). The evidence-base describing the impact of visual impairment (VI) on quality-of-life is very limited. To date, the Czoski-Murray et al. (2009) utility values for 4 visual health severity groups are considered the most plausible set of utility values for use in eye-disorder economic models. These utility values, originally elicited through simulating VI similar to that associated with wet age-related macular degeneration, were recently applied in other retinal disorders such as diabetic macular edema. The objective of our analysis was to refine the mapping of utilities onto visual acuity (VA). OLS regression models were built to estimate the relationship between mid-point VA of 4 visual health severity groups and mean TTO scores as described in the literature. Linear and non-linear approaches for utility estimation as a function of the number of VA letters were explored. The linear regression for utility estimation was found to be statistically significant. The beta-coefficient for mid-point VA was 0.0054 (p=0.030) and 0.2864 for the constant term (p=0.034). Linear regression estimates were used to predict the utility value for 6 pre-specified VA health states: VA1 (0.766); VA2 (0.671); VA3 (0.616); VA4 (0.562); VA5 (0.507); VA6 (0.382). Published evidence on utility values for deterministic visual health severity groups may not easily transpose to alternative vision health-states. Our analysis demonstrated an original approach for utility estimation allowing a more flexible and robust method to map previously elicited VA-associated utilities onto alternate VA health-states. This method allows wider applicability of VA-associated utility estimation in other eye disorders characterized by VA impairment such as vitreomacular traction and macular hole.

Elicitation of health state utilities associated with differing durations of morning stiffness in rheumatoid arthritis

Objective:Specific symptoms of rheumatoid arthritis (RA), including joint stiffness and functional disability, are most severe in the morning. ‘Morning stiffness’ has a negative impact on health-related quality-of-life (HRQoL); however, how HRQoL is correlated to morning stiffness duration is unknown. The objective of this study was to obtain population-based utility values associated with different durations of morning stiffness in RA.Design and methods:The time-trade-off (TTO) approach was used to elicit utility values for four different health states (HS), which differed in morning stiffness duration. One hundred and nine members of the UK general public rated each HS in individual face-to-face interviews with trained investigators. TTO scores were converted into utility values. Visual Analog Scale (VAS) scores were obtained to validate TTO scores.Results:On a scale of 0 (death) to 1 (full health), a mean utility value of 0.45 ± 0.29 was elicited for ∼3 h of morning stiffness (anchor HS), 0.50 ± 0.28 for 2–3 h of morning stiffness (HS1), 0.61 ± 0.25 for 1–2 h of morning stiffness (HS2) and 0.78 ± 0.20 for <1 h of morning stiffness (HS3). The difference between each HS was statistically significant (p < 0.01). Mean VAS utility scores followed the same trend. Utility incrementally increased with each HS associated with a shorter duration of morning stiffness. Limitations of this research include potential bias from the TTO method due to the discounting effect of time, scale compatibility, and loss aversion.Conclusions:The UK population-based utility values show a reduction in morning stiffness duration in RA is associated with improved HRQoL. Despite the impact of morning stiffness on HRQoL, it is rarely evaluated and little is known as to how it is affected by current treatments. The results of this study can be applied in future cost-utility analyses of healthcare interventions which target an improvement in morning stiffness duration for RA patients.

Perceived and Actual Quality of Life With Ulcerative Colitis: A Comparison of Medically and Surgically Treated Patients

Patients with chronic ulcerative colitis (UC) often refuse colectomy, despite data indicating that it might improve quality of life. We hypothesized that perceived utility values are different for patients living with UC compared with UC patients after total proctocolectomy. Our aims were to compare the perceived utility assigned by UC patients with and without a colectomy to standardized chronic UC and post-colectomy scenarios, and to compare the utility of actual health states among groups. We surveyed patients in a tertiary referral center from three groups, including non-UC, UC patients without colectomy, and UC patients who were post-colectomy. We measured the Time-Trade-Off (TTO) utilities of subjects for standardized scenarios, describing moderate UC and a post-colectomy state. Among all UC patients (with and without colectomy), we measured TTO utility for their own health state. Responses were obtained from 150 patients per group (n=450). The non-UC patients considered UC and colectomy scenarios equally (0.92), which was similar to UC patients without colectomy (0.90 and 0.91). Post-colectomy patients strongly preferred the colectomy scenario to the UC scenario (0.86 vs. 0.92, P<0.001). The median utility of UC patients without colectomy for their actual health state was higher than that of post-colectomy patients (0.96 and 0.92, P<0.05). Patients with more social support were more likely to have undergone colectomy compared with patients with little social support (odds ratio=1.20 per dependent/supporter). Patients living with UC prefer their actual health state to a perceived UC scenario or a post-colectomy scenario. Patients who have undergone colectomy equate the quality of life in their actual state with that in a post-colectomy scenario, and prefer each to a perceived chronic UC state. Given the variety of preferences and the importance of social support, opportunities to interact with UC patients who have previously undergone colectomy could help patients living with UC and their physicians to navigate these complex choices.

Health-Related Quality of Life in Patients with Chronic Gastrointestinal Hemorrhage

Background: Patients with acute gastrointestinal bleeding (GIB) have previously demonstrated diminished health-related quality of life. HRQOL has not been defined in patients with chronic GIB. Health-state utilities are preference-weighted measures of HRQOL. Prior studies using hypothetical estimates for acute GIB states demonstrated utility values with the time-tradeoff (TTO) technique of 0.76-0.84. The aim of this study was to derive TTO values in patients with chronic obscure GIB. Methods: Patients who had undergone prior capsule endoscopy (CE) or double balloon enteroscopy (DBE) for evaluation of obscure GIB were invited. We created a custom-designed computer program that asked patients about the duration and chronicity of bleeding and other co-morbid conditions. Patients were presented with current estimates of life expectancy and were asked to trade time in exchange for resolution of chronic GIB. Interviews occurred with a trained research assistant. Results: We invited 62 patients who had undergone prior CE or DBE. 21 (34%) patients (10 men, 11 women, mean ( ± SD) age 66 ± 13 years, range 45-89 years) were enrolled. All patients had iron-deficiency anemia, 7 reported prior hematochezia and 12 presented with melena. The mean duration of chronic anemia was 7.6 ± 8 years (range 1-30 years) and 16 (76%) had received prior blood transfusions. 13 (62%) had completed college education and/or graduate school and 15 (71%) earned ≤$50,000 per year. All patients suffered from co-morbid conditions. DBE was performed in 21 (100%) patients, CE in 19 (90%), and angiography in 11(52%). 10 (48%) patients reported persistent anemia/bleeding despite DBE and/or other procedures. In the 11 patients without further bleeding, the last bleeding episode occurred within a mean of 28 ± 17 (range 12-52) weeks prior to the interview. The source of bleeding was small bowel AVMs in 9 (43%), and presumed colonic diverticulosis in 4 (19%). Seven (33%) patients had no bleeding source detected. The mean score on the visual analog scale (rated from 0-100% where 0 = death and 100 = perfect health) was 62% ± 20% (range 25%-90%). The mean time-tradeoff value was 0.84 ± 0.15 (range 0.5-1.0). TTO values did not differ between patients with current or prior bleeding. (p = 0.4) The mean scores on the SF-36 for all 8 subscales were markedly below the normal scores for the U.S. population and prior scores reported for GERD, depression, and diabetes mellitus. Conclusions: Obscure GI bleeding adversely affects health-related quality of life. Future studies are warranted to determine the impact of endoscopic therapy on HRQOL in patients with chronic obscure bleeding.

Health-related quality of life and health utility for the institutional elderly in Taiwan

To explore the health-related quality of life (HRQOL) and health utility in an institutional elderly population. Four hundred sixty-five elderly persons living in long-term care institutions in Taiwan were interviewed using Taiwan's abbreviated version of the World Health Organization Quality of Life (WHOQOL-BREF), rating scale (RS) and the Time-Trade-Off (TTO) utility measurement. The WHOQOL-BREF showed acceptable internal consistency (alpha range: 0.75-0.80 across domains) and validity. The sexual activity facet had the lowest response rate. Educational level, number of chronic diseases, physical performance, and number of caregivers had significant (p < 0.05) impacts on the domain scores of the WHOQOL-BREF. Physical performance had the strongest impact on the physical domain (R2 = 0.40) and accounted for significant percentages of the variance on the other three domains (R2 = 0.06-0.13). The mean RS score (score 0-100) was 61.3 +/- 16.2 (mean +/- SD). The mean TTO utility (score 0-1) was 0.92 +/- 0.22. Results indicate that the WHOQOL-BREF, excepting the sexual activity item, is useful for evaluating HRQOL of conscious elderly in institutions. The validity of TTO utility for studying the institutionalized elderly needs further evaluation.

Cost-utility analysis of the cochlear implant in children.

Barriers to the use of cochlear implants in children with profound deafness include device costs, difficulty assessing benefit, and lack of data to compare the implant with other medical interventions. To determine the quality of life and cost consequences for deaf children who receive a cochlear implant. Cost-utility analysis using preintervention, postintervention, and cross-sectional surveys conducted from July 1998 to May 2000. Hearing clinic at a US academic medical center. Parents of 78 profoundly deaf children (average age, 7.5 years) who received cochlear implants. Direct and total cost to society per quality-adjusted life-year (QALY) using the time-trade-off (TTO), visual analog scale (VAS), and Health Utilities Index-Mark III (HUI), discounting costs and benefits 3% annually. Parents rated their child's health state at the time of the survey and immediately before and 1 year before implantation. Recipients had an average of 1.9 years of implant use. Mean VAS scores increased by 0. 27, from 0.59 before implantation to 0.86 at survey. In a subset of participants, TTO scores increased by 0.22, from 0.75 to 0.97 (n = 40) and HUI scores increased by 0.39, from 0.25 to 0.64 (n = 22). Quality-of-life scores were no different 1 year before and immediately before implantation. Discounted direct costs were $60,228, yielding $9,029 per QALY using the TTO, $7,500 per QALY using the VAS, and $5,197 per QALY using the HUI. Including indirect costs such as reduced educational expenses, the cochlear implant provided a savings of $53,198 per child. Cochlear implants in profoundly deaf children have a positive effect on quality of life at reasonable direct costs and appear to result in a net savings to society. JAMA. 2000;284:850-856

Comparing three versions of the time tradeoff: time for a change?

This paper reports a comparative study of three formulations of the time-tradeoff (TTO) method of health valuation. One asks people to consider giving up time each day in exchange for better health. The second asks people to consider giving up time during a 12-month interval. The third is the more conventional TTO in which people are asked to contemplate a reduction in life expectancy. Questionnaires were sent to 4,087 adults selected at random from the population of Scotland. Each respondent provided a description of his or her health, and was asked to value an improvement in that health, using all three formulations of the TTO. The daily TTO appeared to be an improvement on the conventional formulation, correlating more strongly with health, eliciting responses that appeared to be more precise and obtaining information about the value of health from a far greater number of respondents. The performance of the annual TTO appeared to be only slightly inferior to that of the daily TTO.