Impact of country-specific EQ-5D-3L tariffs on the economic value of systemic therapies used in the treatment of metastatic pancreatic cancer

Conceptual Framework for Optimised Proxy Value Set Selection Through Supra-National Value Set Development for the EQ-5D Instruments

BACKGROUND

Preference differences between countries and populations justify the use of country-specific value sets for the EQ-5D instruments. There are no clear criteria based on which the selection of value sets for countries without a national value set should be made. As part of the European PECUNIA project, this study aimed to identify factors contributing to differences in preference-based valuations and develop supra-national value sets for homogenous country clusters in Europe.

METHODS

A literature review was conducted to identify factors relevant to variations in the EQ-5D-3L/5L health state valuations across countries. Factors fulfilling the pre-specified criteria of validity, reliability, international feasibility and comparability were used to group 27 European Union member states, the European Free Trade Association countries and the UK. Clusters of countries were developed based on the frequency of their appearance in the same grouping. The supra-national value sets were estimated for these clusters from the coefficients of existing published valuation studies using the ordinary least-squares model.

RESULTS

Ten factors were identified from 69 studies. From these, five grouping variables: (1) culture and religion; (2) linguistics; (3) healthcare system typology; (4) healthcare system financing; and (5) sociodemographic aspects were derived to define the groups of homogenous countries. Frequency-based grouping revealed five cohesive clusters: English-speaking, Nordic, Central-Western, Southern and Eastern European.

CONCLUSIONS

European countries were clustered considering variables that may relate to differences in health state valuations. Supra-national value sets provide optimised proxy value set selection in the lack of a national value set and/or for regional decision making.

Cost-Effectiveness of a Risk-Tailored Pancreatic Cancer Early Detection Strategy Among Patients With New-Onset Diabetes

BACKGROUND & AIMS

Screening for pancreatic ductal adenocarcinoma (PDAC) in asymptomatic adults is not recommended, however, patients with new-onset diabetes (NoD) have an 8 times higher risk of PDAC than expected. A novel risk-tailored early detection strategy targeting high-risk NoD patients might improve PDAC prognosis. We sought to evaluate the cost effectiveness of this strategy.

METHODS

We compared PDAC early detection strategies targeting NoD individuals age 50 years and older at various minimal predicted PDAC risk thresholds vs standard of care in a Markov state-transition decision model under the health care sector perspective using a lifetime horizon.

RESULTS

At a willingness to pay (WTP) threshold of $150,000 per quality-adjusted life-year, the early detection strategy targeting patients with a minimum predicted 3-year PDAC risk of 1% was cost effective (incremental cost-effectiveness ratio, $116,911). At a WTP threshold of $100,000 per quality-adjusted life-year, the early detection strategy at the 2% risk threshold was cost effective (incremental cost-effectiveness ratio, $63,045). The proportion of PDACs detected at local stage, costs of treatment for metastatic PDAC, utilities of local and regional cancers, and sensitivity of screening were the most influential parameters. Probabilistic sensitivity analysis confirmed that at a WTP threshold of $150,000, early detection at the 1.0% risk threshold was favored (30.6%), followed by the 0.5% risk threshold (20.4%) vs standard of care (1.7%). At a WTP threshold of $100,000, early detection at the 1.0% risk threshold was favored (27.3%) followed by the 2.0% risk threshold (22.8%) vs standard of care (2.0%).

CONCLUSIONS

A risk-tailored PDAC early detection strategy targeting NoD patients with a minimum predicted 3-year PDAC risk of 1.0% to 2.0% may be cost effective.

Health-related quality of life in patients with recurrent Clostridioides difficile infections

BACKGROUND

The health-related quality of life (HrQoL) can be substantially affected in patients with recurrent Clostridioides difficile infection (rCDI) but the impact of effective treatment of the infection remains unclear. This study aimed to evaluate the HrQoL in patients with rCDI and estimate the gain in HrQoL associated with effective treatment of rCDI.

METHODS

Patients' HrQoL was estimated based on EuroQol 5-Dimensions 3-Levels (EQ-5D-3L) questionnaires obtained from a Danish randomised controlled trial (RCT). In the RCT, 64 patients with rCDI were randomised to receive either vancomycin (n = 16), fidaxomicin (n = 24) or faecal microbiota transplantation (FMT) preceded by vancomycin (n = 24). The primary outcome in the RCT was rCDI resolution. Patients were closely monitored during the RCT, and rescue FMT was offered to those who failed their primary treatment. Patients' HrQoL was measured at baseline and at 8- and 26-weeks follow-up. Linear regression analyses conditional on the differences between baseline and follow-up measurements were used to assess statistical significance (p < 0.05).

RESULTS

Within 26 weeks of follow-up, 13 (81%) patients treated with vancomycin, 12 (50%) patients treated with fidaxomicin, and 3 (13%) patients treated with FMT had a subsequent recurrence and received a rescue FMT. The average HrQoL for untreated patients with rCDI was 0.675. After receiving effective treatment, this value increased by 0.139 to 0.813 (p < 0.001) at week 8 and by 0.098 to 0.773 (p = 0.003) at week 26 of follow-up compared with baseline.

CONCLUSION

The HrQoL was adversely affected in patients with an active episode of rCDI but increased substantially after receiving an effective treatment algorithm in which rescue FMT was provided in case of a primary treatment failure.

TRIAL REGISTRATION

The RCT was preregistered at EudraCT (j.no. 2015-003004-24, https://www.clinicaltrialsregister.eu/ctr-search/trial/2015-003004-24/results) and at ClinicalTrials.gov (study identifier NCT02743234, https://clinicaltrials.gov/ct2/show/NCT02743234).

Cost-effectiveness analysis of including contrast-enhanced ultrasound in management of pancreatic cystic neoplasms

PURPOSE

Pancreatic cystic neoplasms (PCN) management consists of non-invasive imaging studies (CT, MRI), with a high resource burden. We aimed to determine the cost-effectiveness of including contrast-enhanced ultrasound (CEUS) in the management of PCN without risk features.

MATERIALS AND METHODS

By using a decision-tree model in a hypothetical cohort of patients, we compared management strategy including CEUS with the latest Fukuoka consensus, European and Italian guidelines. Our strategy for BD-IPMN/MCN < 1 cm includes 1 CEUS annually. For those between 1 and 2 cm, it includes CEUS 4 times/year during the first year, then 3 times/year for 4 years and then annually. For those between 2 and 3 cm, it comprises MRI twice/year during the first one, then alternating 2 CEUS and 1 MRI yearly.

RESULTS

CEUS surveillance is the dominant strategy in all scenarios. CEUS surveillance average cost is 1,984.72 €, mean QALY 11.79 and mean ICER 181.99 €. If willingness to pay is 30,000 €, 45% of patients undergone CEUS surveillance of BDIPMN/MCN < 1 cm would be within budget.

CONCLUSION

Guidelines strategies are very effective, but costs are relatively high from a policy perspective. CEUS surveillance may be a cost-effective strategy yielding a nearly high QALYs, an acceptable ICER, and a lower cost.

Assessing the Impact of EQ-5D Country-specific Value Sets on Cost-utility Outcomes

PURPOSE

To assess the impact of EQ-5D country-specific value sets on cost-utility outcomes.

METHODS

Data from 2 randomized controlled trials on low back pain (LBP) and depression were used. 3L value sets were identified from the EuroQol Web site. A nonparametric crosswalk was employed for each tariff to obtain the likely 5L values. Differences in quality-adjusted life years (QALYs) between countries were tested using paired t tests, with United Kingdom as reference. Cost-utility outcomes were estimated for both studies and both EQ-5D versions, including differences in QALYs and cost-effectiveness acceptability curves.

RESULTS

For the 3L, QALYs ranged between 0.650 (Taiwan) and 0.892 (United States) in the LBP study and between 0.619 (Taiwan) and 0.879 (United States) in the depression study. In both studies, most country-specific QALY estimates differed statistically significantly from that of the United Kingdom. Incremental cost-effectiveness ratios ranged between &OV0556;2044/QALY (Taiwan) and &OV0556;5897/QALY (Zimbabwe) in the LBP study and between &OV0556;38,287/QALY (Singapore) and &OV0556;96,550/QALY (Japan) in the depression study. At the NICE threshold of &OV0556;23,300/QALY (≈£20,000/QALY), the intervention's probability of being cost-effective versus control ranged between 0.751 (Zimbabwe) and 0.952 (Taiwan) and between 0.230 (Canada) and 0.396 (Singapore) in the LBP study and depression study, respectively. Similar results were found for the 5L, with extensive differences in ICERs and moderate differences in the probability of cost-effectiveness.

CONCLUSIONS

This study indicates that the use of different EQ-5D country-specific value sets impacts on cost-utility outcomes. Therefore, to account for the fact that health state preferences are affected by sociocultural differences, relevant country-specific value sets should be used.

Psychometric properties of the EQ-5D-5L: a systematic review of the literature

PURPOSE

Although the EQ-5D has a long history of use in a wide range of populations, the newer five-level version (EQ-5D-5L) has not yet had such extensive experience. This systematic review summarizes the available published scientific evidence on the psychometric properties of the EQ-5D-5L.

METHODS

Pre-determined key words and exclusion criteria were used to systematically search publications from 2011 to 2019. Information on study characteristics and psychometric properties were extracted: specifically, EQ-5D-5L distribution (including ceiling and floor), missing values, reliability (test-retest), validity (convergent, known-groups, discriminate) and responsiveness (distribution, anchor-based). EQ-5D-5L index value means, ceiling and correlation coefficients (convergent validity) were pooled across the studies using random-effects models.

RESULTS

Of the 889 identified publications, 99 were included for review, representing 32 countries. Musculoskeletal/orthopedic problems and cancer (n = 8 each) were most often studied. Most papers found missing values (17 of 17 papers) and floor effects (43 of 48 papers) to be unproblematic. While the index was found to be reliable (9 of 9 papers), individual dimensions exhibited instability over time. Index values and dimensions demonstrated moderate to strong correlations with global health measures, other multi-attribute utility instruments, physical/functional health, pain, activities of daily living, and clinical/biological measures. The instrument was not correlated with life satisfaction and cognition/communication measures. Responsiveness was addressed by 15 studies, finding moderate effect sizes when confined to studied subgroups with improvements in health.

CONCLUSIONS

The EQ-5D-5L exhibits excellent psychometric properties across a broad range of populations, conditions and settings. Rigorous exploration of its responsiveness is needed.

Cost-Effectiveness of Maintenance Olaparib for Germline BRCA-Mutated Metastatic Pancreatic Cancer

Background: Maintenance therapy with the PARP inhibitor olaparib for metastatic pancreatic cancer (MPC) with a germline BRCA1 or BRCA2 mutation has been shown to be effective. We aimed to evaluate the cost-effectiveness of maintenance olaparib for MPC from the US payer perspective. Materials and Methods: A partitioned survival model was adopted to project the disease course of MPC. Efficacy and toxicity data were gathered from the Pancreas Cancer Olaparib Ongoing (POLO) trial. Transition probabilities were estimated from the reported survival probabilities in each POLO group. Cost and health preference data were derived from the literature. The incremental cost-utility ratio, incremental net-health benefit, and incremental monetary benefit were measured. Subgroup analysis, one-way analysis, and probabilistic sensitivity analysis were performed to explore the model uncertainties. Results: Maintenance olaparib had an incremental cost-utility ratio of $191,596 per additional progression-free survival (PFS) quality-adjusted life-year (QALY) gained, with a high cost of $132,287 and 0.691 PFS QALY gained, compared with results for a placebo. Subgroup analysis indicated that maintenance olaparib achieved at least a 16.8% probability of cost-effectiveness at the threshold of $200,000/QALY. One-way sensitivity analyses revealed that the results were sensitive to the hazard ratio of PFS and the cost of olaparib. When overall survival was considered, maintenance olaparib had an incremental cost-utility ratio of $265,290 per additional QALY gained, with a high cost of $128,266 and 0.483 QALY gained, compared with results for a placebo. Conclusions: Maintenance olaparib is potentially cost-effective compared with placebo for patients with a germline BRCA mutation and MPC. Economic outcomes could be improved by tailoring treatment based on individual patient factors.

A cost-utility analysis of atezolizumab in the second-line treatment of patients with metastatic bladder cancer

Background

Despite initial promising results, the IMvigor211 clinical trial failed to demonstrate an overall survival (os) benefit for atezolizumab compared with chemotherapy as second-line treatment for metastatic bladder cancer (mbc). However, given lessened adverse events (aes) and preserved quality of life (qol) with atezolizumab, there might still be investment value. To evaluate that potential value, we conducted a cost-utility analysis (cua) of atezolizumab compared with chemotherapy from the perspective of the Canadian health care payer.

Methods

A partitioned survival model was used to evaluate atezolizumab compared with chemotherapy over a lifetime horizon (5 years). The base-case analysis was conducted for the intention-to-treat (itt) population, with additional scenario analyses for subgroups by IMvigor-defined PD-L1 status. Health outcomes were evaluated through life-year gains and quality-adjusted life-years (qalys). Cost estimates in 2018 Canadian dollars for systemic treatment, aes, and end-of-life care were incorporated. The incremental cost-effectiveness ratio (icer) was used to compare treatment strategies. Parameter and model uncertainty were assessed through sensitivity and scenario analyses. Per Canadian guidelines, cost and effectiveness were discounted at 1.5%.

Results

For the itt population, the expected qalys for atezolizumab and chemotherapy were 0.75 and 0.56, with expected costs of $90,290 and $8,466 respectively. The resultant icer for atezolizumab compared with chemotherapy was $430,652 per qaly. Scenario analysis of patients with PD-L1 expression levels of 5% or greater led to a lower icer ($334,387 per qaly). Scenario analysis of observed compared with expected benefits demonstrated a higher icer, with a shorter time horizon ($928,950 per qaly).

Conclusions

Despite lessened aes and preserved qol, atezolizumab is not considered cost-effective for the second-line treatment of mbc.

Toward a Smaller Design for EQ-5D-5L Valuation Studies

BACKGROUND

To construct an EQ-5D-5L value set, the EuroQol Group developed a standard protocol named EuroQol Valuation Technology (EQ-VT), prescribing the valuation of 86 health states utilizing the composite time trade-off (cTTO) approach, and subsequently modeled the observed values to yield values for all 3125 states.

OBJECTIVE

A recent study demonstrated that a 25-state orthogonal design could provide as accurate predictions as the EQ-VT design applying visual analogue scale data. We aimed to test that design using time trade-off (TTO) data.

METHOD

We collected TTO values utilizing EQ-VT, orthogonal, and D-efficient designs. The EQ-VT design included 86 health states distributed over 3 blocks of 30 states with some duplicates. The orthogonal and D-efficient designs each comprised 1 block of 30 states. A total of 525 university students were asked to value a random block of health states using EQ-PVT (a PowerPoint replica of EQ-VT software), which generated 100 observations per health state in all 3 designs. We modeled data by design and compared the root mean square error (RMSE) between observed and predicted values within and across the designs.

RESULTS

The EQ-VT design had the lowest RMSE of 0.052; the RMSEs for the orthogonal and the D-efficient designs were 0.066 and 0.063, respectively. RMSE results between designs differed for more severe health states. Some coefficients differed between designs.

CONCLUSION

Smaller designs did not lead to significant increases in prediction errors when modeling TTO data (measuring 0.01 on a utility scale). Resource-constrained countries may use small designs for valuation studies, especially when other types of preference data, such as those from discrete choice experiments, are collected and modeled jointly.

Vision utilities in Italy and the United States: Comparison of time tradeoff vision utilities

Background/Aims:

To compare time tradeoff vision utilities from two developed Western countries to ascertain whether these vision-related, quality-of-life preferences are similar.

Methods:

Time tradeoff utilities were acquired from ophthalmology patient populations with ophthalmic pathologic conditions by personal interview in Italy and the United States using a reliable and previously validated, standardized questionnaire.

Results:

Data from 47 consecutive Italian participants and 325 consecutive American participants were compared. The populations were matched for gender, age, and ophthalmic pathologic conditions. The utilities for the various vision sub-cohort levels, characterized according to vision in the better-seeing eye for the Italian/American cohorts were as follows: (1) 20/20 sub-cohort, Italian/American mean utilities = 0.82/0.91 (p = 0.10); (2) 20/25–20/30 sub-cohort, Italian/American mean utilities = 0.79/0.86, (p = 0.05); (3) 2040–20/100 sub-cohort, Italian/American mean utilities = 0.76/0.74 (p = 0.70); and (4) 20/200 or less sub-cohort, Italian/American mean utilities = 0.66/0.58 (p = 0.58).

Conclusion:

Vision-related quality of life, as measured by time tradeoff utilities, was similar in Italian and American ophthalmic populations. This information is relevant when comparing quality of life and cost-utility analyses across international borders.

Disability weights for infectious diseases in four European countries: comparison between countries and across respondent characteristics

Background

In 2015, new disability weights (DWs) for infectious diseases were constructed based on data from four European countries. In this paper, we evaluated if country, age, sex, disease experience status, income and educational levels have an impact on these DWs.

Methods

We analyzed paired comparison responses of the European DW study by participants’ characteristics with separate probit regression models. To evaluate the effect of participants’ characteristics, we performed correlation analyses between countries and within country by respondent characteristics and constructed seven probit regression models, including a null model and six models containing participants’ characteristics. We compared these seven models using Akaike Information Criterion (AIC).

Results

According to AIC, the probit model including country as covariate was the best model. We found a lower correlation of the probit coefficients between countries and income levels (range r_s: 0.97–0.99, P < 0.01) than between age groups (range r_s: 0.98–0.99, P < 0.01), educational level (range r_s: 0.98–0.99, P < 0.01), sex (r_s = 0.99, P < 0.01) and disease status (r_s = 0.99, P < 0.01). Within country the lowest correlations of the probit coefficients were between low and high income level (range r_s = 0.89–0.94, P < 0.01).

Conclusions

We observed variations in health valuation across countries and within country between income levels. These observations should be further explored in a systematic way, also in non-European countries. We recommend future researches studying the effect of other characteristics of respondents on health assessment.

Cost-Utility Analysis Using EQ-5D-5L Data: Does How the Utilities Are Derived Matter?

OBJECTIVES

To explore how the use of EQ-5D-5L value set and crosswalk from EQ-5D-5L to EQ-5D-3L (and use of 3L value set) would affect cost-effectiveness analysis results for England and six other countries (Canada, the Netherlands, China, Japan, South Korea, and Singapore).

METHODS

Individual-level utilities derived from primary 5L data using both value set (5L) and crosswalk (c5L) approaches were applied to three Markov models assessing the cost-effectiveness of hemodialysis (HD) and peritoneal dialysis (PD) for end-stage renal disease (ESRD) patients to estimate incremental quality-adjusted life years (QALYs). The mathematic functions between incremental QALY and utility were derived.

RESULTS

5L- and c5L-based incremental QALYs were similar in the model for non-diabetic patients (range: 1.910-2.149, 1.922-2.121). 5L tends to generate more incremental QALYs than c5L in the model for diabetic patients (range: 1.454-1.633, 1.365-1.568) but fewer incremental QALYs in the model for all ESRD patients (range: 0.290-0.480, 0.315-0.493). In all models, 5L (c5L) generated more incremental QALYs when Chinese (South Korean) value sets were used. The largest and smallest differences in 5L- and c5L-based incremental QALYs were observed when Chinese and Dutch value sets were used. Incremental QALYs was a positive linear function of both utility of PD and difference in utilities of HD and PD.

CONCLUSIONS

The value set and crosswalk approaches may not be used interchangeably in economic evaluation when EQ-5D-5L data are used to estimate utilities. Results of cost-effectiveness analysis using Markov models may be affected by both absolute utilities and their differences.

Direct Mapping of the QLQ-C30 to EQ-5D Preferences: A Comparison of Regression Methods

BACKGROUND

Several mapping or cross-walking algorithms for deriving utilities from the European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire for Cancer (EORTC QLQ-C30) scores have been published in recent years. However, the large majority used ordinary least squares (OLS) regression, which proved to be not very accurate because of the specifics of the quality-of-life measures.

OBJECTIVE

Our objective was to compare regression methods that have been used to map EuroQol 5 Dimensions 3 Levels (EQ-5D-3L) utility values from the general EORTC QLQ-C30 using OLS as a benchmark while fixing the number of explanatory variables and to explore an alternative three-part model.

METHODS

We conducted a regression analysis of predicted EQ-5D-3L utilities generated using data from an observational study in ambulatory patients with non-small-cell lung cancer in a Toronto hospital. Six alternative regression methods were compared with a simple OLS regression as benchmark. The six alternative regression models were Tobit, censored least absolute deviation, normal mixture, beta, zero-one inflated beta and a mix of piecewise OLS and logistic regression.

RESULTS

The best predictive fit was obtained by a mix of OLS regression(s) for utilities lower than 1 with a cut-off point of 0.50 and a separate binary logistic regression for utilities equal to one. Zero-one inflated beta regression was also promising. However, OLS regression proved to be the most accurate for the mean. The prediction of utilities equal to one was poor in all regression approaches.

CONCLUSIONS

Three-part regression methods that separately target low, medium and high (<0.50, 0.51-0.99 or 1) utilities seem to have better prediction power than OLS with EQ-5D-3L data, although OLS also seems quite robust. Exploration of three-part approaches compared with single (OLS) regression should be further tested in other similar datasets or using individual pooled data from various clinical or observational studies. The use of alternative goodness-of-fit measures for mapping studies and their influence on the choice of the best performing methods should also be investigated.

Conducting EQ-5D Valuation Studies in Resource-Constrained Countries: The Potential Use of Shrinkage Estimators to Reduce Sample Size

BACKGROUND

Resource-constrained countries have difficulty conducting large EQ-5D valuation studies, which limits their ability to conduct cost-utility analyses using a value set specific to their own population. When estimates of similar but related parameters are available, shrinkage estimators reduce uncertainty and yield estimators with smaller mean square error (MSE). We hypothesized that health utilities based on shrinkage estimators can reduce MSE and mean absolute error (MAE) when compared to country-specific health utilities.

METHODS

We conducted a simulation study (1,000 iterations) based on the observed means and standard deviations (or standard errors) of the EQ-5D-3L valuation studies from 14 counties. In each iteration, the simulated data were fitted with the model based on the country-specific functional form of the scoring algorithm to create country-specific health utilities ("naïve" estimators). Shrinkage estimators were calculated based on the empirical Bayes estimation methods. The performance of shrinkage estimators was compared with those of the naïve estimators over a range of different sample sizes based on MSE, MAE, mean bias, standard errors and the width of confidence intervals.

RESULTS

The MSE of the shrinkage estimators was smaller than the MSE of the naïve estimators on average, as theoretically predicted. Importantly, the MAE of the shrinkage estimators was also smaller than the MAE of the naïve estimators on average. In addition, the reduction in MSE with the use of shrinkage estimators did not substantially increase bias. The degree of reduction in uncertainty by shrinkage estimators is most apparent in valuation studies with small sample size.

CONCLUSION

Health utilities derived from shrinkage estimation allow valuation studies with small sample size to "borrow strength" from other valuation studies to reduce uncertainty.

Current status on the place of FOLFIRINOX in metastatic pancreatic cancer and future directions

Pancreatic cancer (PC) incidence rates are rapidly increasing in developed countries, with half the patients being metastatic at diagnosis. For decades, fluorouracil, then gemcitabine regimens were the preferred palliative first-line options for fit patients with metastatic PC. FOLFIRINOX (a combination of bolus and infusional fluorouracil, leucovorin, irinotecan and oxaliplatin) was introduced to clinical practice in 2010 due to the results of the phase II/III trial (PRODIGE 4/ACCORD 11) comparing FOLFIRINOX with single-agent gemcitabine as first-line treatment for patients with MPC. Median overall survival, progression-free survival, and objective response rate were superior with FOLFIRINOX over gemcitabine and there was prolonged time to definitive deterioration in quality of life. Although FOLFIRINOX was also associated with increased toxicity, mainly febrile neutropenia and diarrhea, there has been rapid uptake of this regimen. This review closely examines optimal management and prevention of toxicities, international recommendations for first-line treatment, and use of modified FOLFIRINOX protocols. In this review, we also look at the potential benefit of FOLFIRINOX in selected groups of patients: second-line therapy, adjuvant chemotherapy, induction therapy in patients with borderline resectable and locally advanced PC. Robust validation of the FOLFIRINOX regimen in these settings requires confirmation in further randomized trials.

A comparison of health utility scores calculated using United Kingdom and Canadian preference weights in persons with alzheimer's disease and their caregivers

Background

The use of the EQ-5D to asses the economic benefits of health technologies has led to questions about the cross-population transferability of preference weights to calculate health utility scores. The aim of this study is to investigate whether the use of UK and Canadian preference weights will lead to the calculation of different health utility scores in a sample of persons with Alzheimer’s disease (AD) and their primary informal caregivers.

Methods

We recruited 216 patient-caregiver dyads from nine geriatric and memory clinics across Canada. Participants used the EQ-5D-3L to rate their health-related quality-of-life (HRQoL). EQ-5D-3L responses were transformed into health utility scores using UK and Canadian preference weights. The levels of agreement between the two sets of scores were assessed using intraclass correlation coefficients (ICCs). Bland-Altman plots depicted individual-level differences between the two sets of scores. Differences in health utility scores were tested using the Wilcoxon signed rank sum test. A generalized linear model with a gamma distribution was used to examine whether participants’ socio-demographic characteristics were associated with their health utility scores.

Results

The distributions of health utility scores derived from both the UK and Canadian preference weights were skewed to the left. The intraclass correlation coefficient was 0.94 (95 % CI: 0.92, 0.95) for persons with AD and 0.92 (95 % CI: 0.88, 0.94) for the caregivers. The Canadian weights yielded slightly higher median health utility scores than the UK weights for caregivers (median difference: 0.009; 95 % confidence interval: 0.007, 0.013). This finding persisted after stratifying by disease severity. Few socio-demographic characteristics were associated with the two sets of health utility scores.

Conclusions

Health utility scores exhibited small and clinically unimportant differences when calculated with UK versus Canadian preference weights in persons with AD and their caregivers. The original UK and Canadian population samples used to obtain the preference weights valued health states similarly.