Challenges in Valuing Temporary Health States for Economic Evaluation: A Review of Empirical Applications of the Chained Time Trade-Off Method

Estimates of Quality-Adjusted Life-Year Loss for Injuries in the United States

PURPOSE

The goal of this study is to develop an approach for estimating nationally representative quality-adjusted life-year (QALY) loss from injury and poisoning conditions using data collected in the Medical Expenditure Panel Survey (MEPS) and the National Health Interview Survey (NHIS).

METHODS

This study uses data from the 2002-2015 NHIS and MEPS surveys. Injuries were identified in the MEPS medical events file and through self-reporting of medical conditions. We restricted our model to 163,731 adults, for which we predict a total of 294,977 EQ-5D scores using responses to the self-administered questionnaire. EQ-5D scores were modeled using age, sex, comorbidities, and binary indicators of the presence and duration of injury at the time of the health status questionnaire. These models consider nonlinearity over time during the first 3 y following the injury event.

RESULTS

Injuries are identified in MEPS using medical events that provide a reasonable proxy for the date of injury occurrence. Health-related quality of life (HRQL) decrements can be estimated using binary indicators of injury during different time periods. When grouped into 29 injury categories, most categories were statistically significant predictors of HRQL scores in the first year after injury. For these groups of injuries, mean first-year QALY loss estimates range from 0.005 (sprains and strains of joints and adjacent muscles, n = 7067) to 0.109 (injury to nerves and spinal cord, n = 71). Fewer estimates are significant in the second and third years after injury, which may reflect a return to baseline HRQL.

CONCLUSION

This research presents both a framework for estimating QALY loss for short-lived medical conditions and nationally representative, community-based HRQL scores associated with a wide variety of injury and poisoning conditions.

HIGHLIGHTS

This research provides a catalog of nationally representative, preference-based EQ-5D score decrements associated with surviving a large set of injuries, based on patient-reported health status.Mean first-year QALY loss estimates range from 0.005 (sprains and strains of joints and adjacent muscles, n = 7067) to 0.109 (injury to nerves and spinal cord, n = 71).This article presents a novel methodology for assessing quality-of-life impacts for acute conditions by calculating the time elapsed between injury and health status elicitation. Researchers may explore adapting these methods to study other short-lived conditions and health states, such as COVID-19 or chemotherapy.

Modelling the Cost-Effectiveness of Diagnostic Tests

Diagnostic tests are used to determine whether a disease or condition is present or absent in a patient, who will typically be suspected of having the disease or condition due to symptoms or clinical signs. Economic evaluations of diagnostic tests (e.g. cost-effectiveness analyses) can be used to determine whether a test produces sufficient benefit to justify its cost. Evidence on the benefits conferred by a test is often restricted to its accuracy, which means mathematical models are required to estimate the impact of a test on outcomes that matter to patients and health payers. It is important to realise the case for introducing a new test may not be restricted to its accuracy, but extend to factors such as time to diagnosis and acceptability for patients. These and other considerations may mean the common modelling approach, the decision tree, is inappropriate for underpinning an economic evaluation. There are no consensus guidelines on how economic evaluations of diagnostic tests should be conducted-this article attempts to explore the common challenges encountered in economic evaluations, suggests solutions to those challenges, and identifies some areas where further methodological work may be necessary.

Health utilities for non-melanoma skin cancers and pre-cancerous lesions: A systematic review

BACKGROUND

Non-melanoma skin cancers (NMSCs) are common and consume many healthcare resources. A health utility is a single preference-based value for assessing health-related quality of life, which can be used in economic evaluations. There are scarce data on health utilities for NMSCs.

OBJECTIVES

Using a systematic review approach, we synthesized the current data on NMSC-related health utilities.

METHODS

A systematic review of studies of NMSC-related health utilities was conducted in Medline, Embase, and Cochrane databases. Data were extracted based on the protocol and a quality assessment was performed for each study.

RESULTS

The protocol resulted in 16 studies, involving 121 621 participants. Mean utility values across the studies ranged from 0.56 to 1 for undifferentiated NMSC, 0.84 to 1 for actinic keratosis, 0.45 to 1 for squamous cell carcinoma, and 0.67 to 1 for basal cell carcinoma. There was considerable variability in utilities by type of cancer, stage of diagnosis, time to treatment, treatment modality, and quality of life instrument or method. Utility values were predominantly based on the EuroQol 5-dimension instrument and ranged from 0.45 to 0.96, while other measurement methods produced values ranging from 0.67 to 1. Lower utility values were observed for advanced cancers and for the time period during and immediately after treatment, after which values gradually returned to pre-treatment levels.

CONCLUSIONS

Most utility values clustered around relatively high values of 0.8 to 1, suggesting small decrements in quality of life associated with most NMSCs and their precursors. Variability in utilities indicates that careful characterization is required for measures to be used in economic evaluations.

A Head-to-Head Comparison of the Standard Quality-Adjusted Life Year Model With the Annual Profile Model

OBJECTIVES

The standard quality-adjusted life year (QALY) model (SQM) assumes time-utility independence within constant health states and additive independence when health varies over time. The validity of SQM has been challenged through reported violations of these assumptions. An alternative approach that relaxes these assumptions is to assign a single valuation to an entire health profile: an integral assessment of disease severity over time. Here, we compare SQM with the annual profile model (APM) and test SQM for additive independence.

METHODS

Eighty-two respondents valued 6 episodic conditions, including 4 of short duration, with SQM and APM, using the time trade-off method. Inter-rater reliability was assessed using intraclass correlation coefficients. Face validity was tested by asking respondents how well they were able to imagine the health states under SQM and APM. We calculated SQM QALY values for a 1-year time period, allowing for a direct comparison with APM values. For the short-term conditions we expected higher QALY values for SQM, violating additive independence.

RESULTS

APM showed higher interrater reliability (intraclass correlation coefficient of 0.53 vs 0.18, respectively) and better face validity than SQM, with 6% (APM) vs 21% (SQM) of all respondents reporting difficulties. Additive independence of SQM was violated in 5 of the 6 conditions (including the 4 short duration health states), with higher QALY values under SQM (mean difference 0.04).

CONCLUSION

The impact of short-term conditions is systematically underestimated under SQM when compared to a health profile model. APM is a less restrictive model and demonstrates better validity.

Health state utilities for metastatic breast cancer in Taiwan

Background

New developments in medications for metastatic breast cancer (MBC) can be of great benefit to patients, but unfortunately these medicines also increase expenditures. Cost-utility analyses (CUAs) are needed to allocate health resources properly, and health utility values are required to calculate quality-adjusted life years in those CUAs.

Objective

The aims of this study were to measure health utility values for several MBC-related health states and certain breast cancer treatment-related grade 3/4 adverse drug reactions (ADRs). In addition, we examined whether different methods and respondents’ characteristics would influence the utility values elicited.

Methods

A cross-sectional survey was conducted. The visual analogue scale (VAS) and time trade-off (TTO) methods were used to measure health utilities. Four MBC and nine ADR health states were selected for evaluation based on literature review and expert opinion. Information about respondents’ demographic and clinical characteristics were collected to examine the relationship between utilities and participant characteristics.

Results

A total of 102 patients participated in this study. The TTO-elicited values were higher than the VAS-derived scores except for two MBC-related health states. Among the MBC health states assessed, the TTO preference score ranged from 0.04 (palliative MBC) to 0.62 (responding MBC). For grade 3/4 ADRs, the mean TTO-derived utility values ranged from 0.35 (nausea/vomiting) to 0.79 (fatigue). The ranking of the preference scores derived from the VAS was similar to that of the TTO-elicited scores.

Conclusion

This study obtained health state utility values for MBC and grade 3/4 ADRs using both the TTO and the VAS, which provides useful data for future CUAs.

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This study obtained health state utility values for metastatic breast cancer (MBC) and grade 3/4 adverse drug reactions (ADRs) using both the time trade-off (TTO) and the visual analogue scale (VAS), which provides useful data for future cost-utility analyses.

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Among the MBC health states assessed, the TTO preference score ranged from 0.04 (palliative MBC) to 0.62 (responding MBC).

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For grade 3/4 ADRs, the mean TTO-derived utility values ranged from 0.35 (nausea/vomiting) to 0.79 (fatigue).

Using Time Trade-Off Methods to Elicit Short-Term Utilities Associated with Treatments for Bulbar Urethral Stricture

BACKGROUND

Recurrent urethral stricture is usually treated with either open urethroplasty or endoscopic urethrotomy. Both of the procedures cause short-term utility loss, which may not be captured by standard utility questionnaires due to the challenges of completing a standard instrument at the time of an acute episode of short duration, especially within a clinical trial setting. We propose to use time trade-off (TTO) methods to estimate these short-term utility losses.

OBJECTIVE

The aim was to compare the use of two alternative TTO methods to elicit patients' short-term utilities following surgical treatments for recurrent urethral stricture.

METHOD

Two variants of TTO (chained and conventional) were used. Six health profiles were developed-three for each procedure. Forty participants took part, with 20 randomly allocated to each TTO method.

RESULTS

Thirty-eight participants provided usable data for analysis. Estimated utility values decreased as the severity of the health profiles increased. There was no evidence that utility values differed between elicitation methods or procedures for mild {ranging from 0.79 (standard deviation [SD] 0.17) to 0.83 [SD 0.20]} and moderate (ranging from 0.54 [SD 0.24] to 0.67 [SD 0.21]) health states, although they appeared to differ for severe health states (ranging from 0.29 [SD 0.20] to 0.56 [SD 0.24]).

CONCLUSION

The study demonstrates the feasibility and value of eliciting patients' short-term utilities. Given the small sample size, the study findings are tentative. Further research with a larger sample size is needed to determine the appropriate TTO method to use and how the elicited utilities can be used in combination with standard cost-utility assessments to aid decision making.

Conducting a Time Trade-Off Study Alongside a Clinical Trial: A Case Study and Recommendations

Time trade-off (TTO) is an established method in health economics to elicit and value individuals' preferences for different health states. These preferences are expressed in the form of health-state utilities that are typically used to measure health-related quality of life and calculate quality-adjusted life-years in an economic evaluation. The TTO approach to directly elicit health-state utilities is particularly valuable when generic instruments (e.g. EQ-5D) may not fully capture changes in utility in a clinical trial. However, there is limited guidance on how a TTO study should be conducted alongside a clinical trial despite it being a valuable tool. We present an account of the design and development of a TTO study within a clinical trial as a case study. We describe the development of materials needed for the TTO interviews, the piloting of the TTO materials and interview process, and recommendations for future TTO studies. This paper provides a practical guide and reference for future applications of the TTO method alongside a clinical trial.

Health State Utilities for Acute Myeloid Leukaemia: A Time Trade-off Study

OBJECTIVES

Acute myeloid leukaemia (AML) is an aggressive haematological cancer associated with significant humanistic impact. The current study assessed how the general public in the United Kingdom (UK) values AML health states.

METHODS

The composite time trade-off (cTTO) methodology was employed to elicit health state utilities in AML. Pertinent AML literature related to symptom and quality-of-life impact including physical, functional and emotional well-being, as well as the safety profile of AML treatments, were taken into consideration for drafting health state descriptions. Ten health states included in the study were newly diagnosed AML, induction, consolidation, maintenance, long-term follow-up, relapsed/refractory, stem-cell transplant (SCT) procedure, SCT recovery, SCT long-term follow-up with complications and SCT long-term follow-up without complications. The descriptions were validated by haematologists and nurse specialists for clinical accuracy and completeness. A total of 210 individuals from the general UK population participated in the cTTO interviews. Descriptive statistics were computed for health state utility values.

RESULTS

The mean age of the participants was 44.0 years (standard deviation [SD] 14.9, range 18-81) and comprised 129 (61.4%) female participants. The utility values ranged from 0.94 (SD 0.13) for SCT long-term follow-up without complications to - 0.21 (SD 0.62) for the SCT procedure.

CONCLUSIONS

The study provides health utilities for a range of AML health states, with the SCT procedure health state being valued worse than death. The utilities obtained in this study can be employed as inputs in cost-effectiveness analyses of AML therapies.