On the ability of the SF-6D to capture the consequences of chronic illnesses on subjective well-being: Evidence from France

Using cross-sectional data from a representative sample of the French population (the 2008 Disability Health survey), this paper examines whether the SF-6D, a widely used preference-based measure of health-related quality of life in economic evaluations, fully captures the variation in subjective well-being (SWB) due to chronic illnesses. We conduct a mediation analysis to disentangle the direct and indirect, through the SF-6D, effects of various chronic conditions on SWB (happiness). Our results show that the SF-6D reflects changes in happiness due to most illnesses except mental illness. Changes in SWB mediated by the SF-6D account for 74% of the total effect. The variation unexplained by the SF-6D is significant and increases substantially in the presence of multimorbidity when a chronic illness is combined with anxiety or depression. Overall, our results suggest that the SF-6D incompletely captures the subjective experience of chronically ill patients, especially those with comorbid conditions.

The quality of life impact of the COVID-19 pandemic and lockdowns for people living with multiple sclerosis (MS): evidence from the Australian MS Longitudinal Study

PURPOSE

People living with multiple sclerosis (PwMS) in metropolitan Victoria, Australia, experienced a 112-day, COVID-19-related lockdown in mid-2020. Contemporaneously, Australian PwMS elsewhere experienced minimal restrictions, resulting in a natural experiment. This study investigated the relationships between lockdowns, COVID-19-related adversity, and health-related quality of life (HRQoL). It also generated health state utilities (HSU) representative of changes in HRQoL.

METHODS

Data were extracted from Australian MS Longitudinal Study surveys, which included the Assessment of Quality of Life-Eight Dimensions (AQoL-8D) instrument and a COVID-19 questionnaire. This COVID-19 questionnaire required participants to rank their COVID-19-related adversity across seven health dimensions. Ordered probits were used to identify variables contributing to adversity. Linear and logit regressions were applied to determine the impact of adversity on HRQoL, defined using AQoL-8D HSUs. Qualitative data were examined thematically.

RESULTS

N = 1666 PwMS (average age 58.5; 79.8% female; consistent with the clinical presentation of MS) entered the study, with n = 367 (22.0%) exposed to the 112-day lockdown. Lockdown exposure and disability severity were strongly associated with higher adversity rankings (p < 0.01). Higher adversity rankings were associated with lower HSUs. Participants reporting major adversity, across measured health dimensions, had a mean HSU 0.161 (p < 0.01) lower than participants reporting no adversity and were more likely (OR: 2.716, p < 0.01) to report a clinically significant HSU reduction. Themes in qualitative data supported quantitative findings.

CONCLUSIONS

We found that COVID-19-related adversity reduced the HRQoL of PwMS. Our HSU estimates can be used in health economic models to evaluate lockdown cost-effectiveness for people with complex and chronic (mainly neurological) diseases.

Health-related quality of life and subjective well-being among children aged 9-12 years in Shandong Province, China

PURPOSE

To investigate the health-related quality of life (HRQoL) and subjective well-being (SWB) of children aged 9-12 years in eastern China, and examine concordance within child self-reported and parent proxy-assessed.

METHODS

Data was collected from 9 to 12 years old children (including their parents) in Shandong Province in 2018. Participants self-completed a hard-copy questionnaire including Child Health Utility 9D (CHU9D), Pediatric Quality of Life Inventory (PedsQL)™ 4.0 Short Form 15 Generic Core Scales (hereafter the PedsQL™), Student's Life Satisfaction Scale (SLSS), as well as information on socio-demographic characteristics and self-report health status. Spearman's correlation coefficients and the difference between sub-groups were conducted to assess and compare the agreement on HRQoL and SWB instruments. Exploratory factor analysis (EFA) was used to ascertain the number of unique underlying latent factors that were associated with the items covered by the two generic HRQoL and the SWB instruments. The concordance of child self-reported and parent proxy-assessed was analyzed using weighted kappa coefficient and Bland-Altman plots.

RESULTS

A total of 810 children and 810 parents were invited to participate in the survey. A valid sample of 799 (98.6%) children and 643 (79.4%) parents completed the questionnaire. The child self-reported mean scores were CHU9D = 0.87, PedsQL™ = 83.47, and SLSS = 30.90, respectively. The parent proxy-assessed mean scores were PedsQL™ = 68.61 and SLSS = 31.23, respectively. The child self-reported PedsQL™ was moderately correlated with the CHU9D (r = 0.52). There was a weak correlation between CHU9D and SLSS (r = 0.27). The EFA result found 3 factors whilst seven SLSS items grouped into a standalone factor (factor 3), and the nine dimensions of CHU9D shared two common factors with the PedsQL™ (factor 1 and factor 2). A low level of concordance was observed across all comparisons and in all domains (weighted kappa < 0.20) between parents and their children. Furthermore, a high level of discordance was observed between child self-reported and father proxy-assessed.

CONCLUSIONS

CHU9D and PedsQL™ instruments have a higher agreement in measuring the HRQoL in children. CHU9D/PedsQL™ and SLSS instruments showed a low agreement and EFA result suggested that measuring SWB in children potentially may provide further information, which might be overlooked by using HRQoL instruments exclusively. Concordance of child self-reported and parent proxy-assessed was poor. Overall, mother-child concordance was higher than father-child concordance.

Measuring the Wellbeing of Cancer Patients with Generic and Disease-Specific Instruments

Different wellbeing measures have been used among cancer patients. This study aimed to first investigate the sensitivity of health state utility (HSU), capability, and subjective wellbeing (SWB) instruments in cancer. A cancer-specific instrument (QLQ-C30) was included and transferred onto the cancer-specific HSU scores. Furthermore, it examined the relative importance of key life domains explaining overall life satisfaction. Data were drawn from the Multi-instrument Comparison survey. Linear regression was used to explore the extent to which the QLQ-C30 sub-scales explain HSU and SWB. Kernel-based Regularized Least Squares (KRLS), a machine learning method, was used to explore the life domain importance of cancer patients. As expected, the QLQ-C30 sub-scales explained the vast majority of the variance in its derived cancer-specific HSU (R² = 0.96), followed by generic HSU instruments (R² of 0.65-0.73) and SWB and capability instruments (R² of 0.33-0.48). The cancer-specific measure was more closely correlated with generic HSU than SWB measures, owing to the construction of these instruments. In addition to health, life achievements, relationships, the standard of living, and future security all play an important role in explaining the overall life satisfaction of cancer patients.

Extending the EQ-5D: the case for a complementary set of 4 psycho-social dimensions

OBJECTIVES

The EQ-5D is the most widely applied preference-based health-related quality of life measure. However, concerns have been raised that the existing dimensional structure lacks sufficient components of mental and social aspects of health. This study empirically explored the performance of a coherent set of four psycho-social bolt-ons: Vitality; Sleep; Personal relationships; and Social isolation.

METHODS

Cross-sectional surveys were conducted with online panel members from five countries (Australia, Canada, Norway, UK, US) (total N = 4786). Four bolt-ons were described using terms aligned with EQ nomenclature. Latent structures among all nine dimensions are studied using an exploratory factor analysis (EFA). The Shorrocks-Shapely decomposition analyses are conducted to illustrate the relative importance of the nine dimensions in explaining two outcome measures for health (EQ-VAS, satisfaction with health) and two for subjective well-being (the hedonic approach of global life satisfaction and an eudemonic item on meaningfulness). Sub-group analyses are performed on older adults (65 +) and socially disadvantaged groups.

RESULTS

Strength of correlations among four bolt-ons ranges from 0.34 to 0.49. As for their correlations with the EQ-5D dimensions, they are generally much less correlated with four physical health dimensions than with mental health dimensions (ranged from 0.21 to 0.50). The EFA identifies two latent factors. When explaining health, Vitality is the most important. When explaining subjective well-being, Social isolation is second most important, after Anxiety/depression.

CONCLUSION

We provide evidence that further complementing the current EQ-5D-5L health state classification system with a coherent set of four bolt-on dimensions that will fill its psycho-social gap.

Evaluating health-related quality of life and subjective wellbeing among infertility patients: a cross-sectional study in mainland China

PURPOSE

This study aimed to explore the health-related quality of life (HRQoL) and subjective wellbeing (SWB) of infertility patients in mainland China and to investigate the relationships between HRQoL and SWB instruments in infertility patients.

METHODS

We conducted this cross-sectional study in the Hospital for Reproductive Medicine Affiliated of Shandong University between April 2019 and November 2019. Participants self-completed the five-level EQ-5D (EQ-5D-5L) questionnaire, the Assessment of Quality of Life (AQoL)-8D, and the WHO-5 wellbeing index (WHO-5). The agreements between EQ-5D-5L and AQoL-8D were assessed employing intraclass correlation coefficient (ICC) and Bland-Altman plots. Exploratory factor analysis (EFA) was conducted to examine the difference in descriptive systems among the three instruments.

RESULTS

We analyzed a valid sample of 618 infertility patients (84.4%). The mean scores of the total EQ-5D-5L, AQoL-8D, and WHO-5 were 0.96 (95%CI 0.96, 0.96), 0.80 (95%CI 0.79, 0.81), and 16.92 (95%CI 16.52, 17.31), respectively. Patients diagnosed with primary infertility had significantly lower HRQoL and SWB than those with secondary infertility. The ICC of EQ-5D-5L and AQoL-8D was 0.14. The AQoL-8D (r = 0.625) was more strongly correlated with WHO-5 than with the EQ-5D-5L (r = 0.262). The EFA results indicated that HRQoL instruments and the WHO-5 instruments were complementary rather than substitutable.

CONCLUSIONS

Poorer HRQoL and SWB were found that primary than secondary infertility patients. There exists a poor agreement between EQ-5D-5L and AQoL-8D and the difference in the psychosocial components may explain the difference. Measuring both HRQoL and SWB could provide complementary information for infertility patients.

How is your life? understanding the relative importance of life domains amongst older adults, and their associations with self-perceived COVID-19 impacts

Purpose

This study aims to provide new knowledge on the relative importance of key life domains amongst older adults, and how the Coronavirus pandemic has influenced their life (domain) satisfaction.

Methods

A cross-sectional survey was administrated to an online panel of the general public aged 65 years and older in Australia from 28 April to 26 May 2020. Life satisfaction was measured by the Personal Wellbeing Index (PWI, including both global life satisfaction and life domain satisfaction). A discrete choice experiment technique was used to elicit how respondents perceive the relative importance of six key life domains drawn from the PWI: standard of living, health, relationships, safety, community connectedness, and future security.

Results

A total of 1,056 respondents (53% female) with a mean (range) age of 73 (65–91) years old completed the survey. After controlling for a rich set of confounding factors, regardless of the choice of overall life satisfaction indicators, there were consistent findings that the strongest negative influence of COVID-19 on life domains and decrements on life satisfaction was for Personal Health, Personal Relationships and Standard of Living. The DCE data revealed that all six life domains were statistically significant in contributing to a better life, and there exists some preference heterogeneity between those who perceived no impact versus negative impacts from COVID-19.

Conclusions

From both revealed and stated preference data there was robust evidence that health, relationships, and standard of living represent the three most important life domains for older adults in Australia.

Supplementary Information

The online version contains supplementary material available at 10.1007/s11136-021-03043-5.

Relationship between health-related quality of life and subjective wellbeing in asthma

OBJECTIVE

Poor health-related quality of life (HRQoL) is associated with a high risk of acute exacerbations in patients with asthma. The use of health state utility instruments to measure HRQoL is common, but it has been criticised for failing to adequately capture the impact of the condition from the patient perspective. We aimed to assess the ability of subjective wellbeing and health state utility instruments to capture important HRQoL dimensions for asthma patients.

METHODS

Regression analyses were conducted using data (n = 856 asthma patients) from a large multi-national cross-sectional survey to explore the relationship between subjective wellbeing (ONS4, PWI, SWLS), health state utility (15D, AQoL-8D, EQ-5D-5L, HUI3, SF-6D, SF-6Dv2), and an asthma-specific instrument (AQLQ-S). The latent structure of different instruments was investigated using an exploratory factor analysis.

RESULTS

All instruments could distinguish the impact of asthma on HRQoL. Among health utility instruments, 15D, SF-6D and AQoL-8D were more sensitive based on the average standardised regression coefficients. AQOL-8D had the strongest correlation with subjective wellbeing. Nevertheless, the exploratory factor analysis showed a complementary relationship between subjective wellbeing and HRQoL instruments. The most important subjective wellbeing domains were standard of living, achieving in life, and personal relationships; although contributions of these domains to overall life satisfaction differed among asthma patients identified by a latent class analysis.

CONCLUSION

The use of subjective wellbeing alongside AQLQ-S and health state utility instruments provides a comprehensive approach to assess the impact of asthma on the patient's life. Further research is needed to incorporate these measures in health care evaluation.

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.

Head-to-Head Comparison of the Psychometric Properties of 3 Carer-Related Preference-Based Instruments

OBJECTIVES

To compare the psychometric properties of the Adult Social Care Outcomes Toolkit for carers (ASCOT-Carer), the Carer Experience Scale (CES), and the Care-related Quality of Life (CarerQol) to inform the choice of instrument in future studies.

METHODS

Data were derived from a 2018 online survey of informal carers in Australia. Reliability was assessed via internal consistency (Cronbach alpha, α) and test-retest reliability (intraclass correlation coefficient, ICC) for respondents who self-reported no change in their quality of life as a carer over 2 weeks. Convergent validity was evaluated via predetermined hypotheses about associations (Spearman's rank correlation) with existing, validated measures. Discriminative validity was assessed based on the ability of the carer-related scores to distinguish between different informal care situations (Mann-Whitney U, Kruskal-Wallis one-way analysis of variance).

RESULTS

Data from 500 carers were analyzed. The ASCOT-Carer demonstrated a higher degree of internal consistency, possibly due to a unidimensional structure, and test-retest reliability than the CarerQol and CES (α = 0.87, 0.65, 0.59; ICC, 0.87, 0.67, 0.81, respectively). All 3 instruments exhibited convergent validity and detected statistically significant associations between carer-related scores and different informal care situations, except for the CarerQol-7D and sole carer status.

CONCLUSIONS

The ASCOT-Carer, CarerQol, and CES performed reasonably well psychometrically; the ASCOT-Carer exhibited the best psychometric properties overall in this sample of Australian informal carers. Findings should be used in conjunction with consideration of research goals, carer population, targeted carer-related constructs, and prevailing perspectives on the economic evaluation to inform choice of instrument in future studies.

Filling the psycho-social gap in the EQ-5D: the empirical support for four bolt-on dimensions

PURPOSE

The EQ-5D is the most widely applied generic preference-based measure (GPBM) of health-related quality of life (HRQoL). Much concern has been raised that its descriptive system is lacking psycho-social dimensions. A recent paper in this journal provided theoretical support for four dimensions to fill this gap. The current paper aims to provide empirical support for these suggested bolt-on dimensions to the EQ-5D.

METHODS

We use data from the comprehensive Multi-Instrument-Comparison (MIC) study. The four proposed bolt-on dimensions (Vitality, Sleep, Social Relationships, and Community Connectedness) were selected from the Assessment of Quality of Life (AQoL)-8D. We investigate the relative importance of these four dimensions as compared to the five EQ-5D-5L dimensions on explaining HRQoL (measured by a visual analogue scale; N = 7846) or global life satisfaction (measured by the Satisfaction With Life Scale; N = 8005), using the Shorrocks-Shapely decomposition analysis. Robustness analyses on Vitality was conducted using data from the United States National Health Measurement Study (NHMS) (N = 3812).

RESULTS

All five EQ-5D-5L dimensions and four bolt-on dimensions significantly explained the variance of HRQoL. Among them, Vitality was found to be the most important dimension with regard to the HRQoL (relative contribution based on the Shorrocks-Shapely decomposition of R2: 23.0%), followed by Usual Activities (15.1%). Self-Care was the least important dimension (relative contribution: 5.4%). As a comparison, when explaining global life satisfaction, Social Relationships was the most important dimension (relative contribution: 24.0%), followed by Anxiety/Depression (23.2%), while Self-Care remained the least important (relative contribution: 1.6%). The importance of the Vitality dimension in explaining HRQoL was supported in the robustness analysis using the NHMS data (relative contribution: 23.7%).

CONCLUSIONS

We provide empirical support for complementing the current EQ-5D-5L descriptive system with a coherent set of four bolt-on dimensions that will fill its psycho-social gap. Such an extended health state classification system would in particular be relevant for programme evaluations within the expanding fields of mental health and community care.

Evaluation of Health Status of Type 2 Diabetes Outpatients Receiving Care in a Tertiary Hospital in Nigeria

OBJECTIVES

The aim of this study was to determine the health status of type 2 diabetes patients in a Nigerian tertiary hospital, and examine the sociodemographic and clinical variables that predicted the health status of type 2 diabetes patients in terms of utility valuations and EuroQol Visual Analogue Scale (EQ-VAS) score.

METHODS

This was a cross-sectional study of 147 diabetes patients attending the University of Nigeria Teaching Hospital, Enugu State, Nigeria. The EQ-5D-5L instrument, version 2.1, was used to evaluate patients' self-reported health status, and patients who gave informed consent completed the questionnaire while waiting to see a doctor. Descriptive and multiple linear regression analyses were performed using SPSS version 20.

RESULTS

Overall, 147 patients participated in this study, with a mean age (± standard deviation) of 56.7 years (± 10.33). Over half of the respondents were females (55.1%) and more than half were older than 60 years of age. The mean EQ-VAS and utility valuations of respondents were 72.59 ± 10.51 and 0.72 ± 0.13, respectively. The age of respondents independently and significantly predicted EQ-VAS by -2.659 per year, while the age of respondents, level of education, duration of diabetes, and presence of other illnesses independently and significantly predicted utility valuations by -0.020 per year, +0.029 per level of education, -0.008 per year, and -0.044 per illness, respectively. Less than 39% of patients experienced no problems for each of the dimensions, except self-care (68%).

CONCLUSION

The results of this study revealed a relatively low health status among type 2 diabetic patients in Nigeria. Old age, duration of diabetes and the presence of other illnesses were major contributors to the negative impact on health status, while a higher level of education contributed positively to health status. Adequate family support, as well as regular and effective patient counseling and education, may be worthwhile.

Using path analysis to investigate the relationships between standardized instruments that measure health-related quality of life, capability wellbeing and subjective wellbeing: An application in the context of spinal cord injury

While economic evaluations typically embrace health maximization as the maximization objective using quality-adjusted life years, there is increasing interest in the measurement of capability wellbeing and subjective wellbeing (SWB) for informing policy decisions. The objective of this study was to investigate the relationships between health-related quality of life (HRQoL), capability wellbeing and SWB. Data were used from 364 individuals living with spinal cord injury (SCI) who previously completed a web-based, cross-sectional survey (March-June 2013). Regression analyses were used to study the impacts of secondary health conditions on HRQoL, capability wellbeing and SWB; subsequently, a path analysis was used to assess direct and mediated pathways. HRQoL was measured using the EQ-5D-5L and the Assessment of Quality of Life 8-dimension (AQoL-8D) questionnaire; capability wellbeing was assessed using the ICEpop CAPability measure for Adults (ICECAP-A), and SWB was based on a single life satisfaction item (0-10 rating scale). Mean scores were 0.492, 0.573, 0.761 and 6.319 for EQ-5D-5L, AQoL-8D, ICECAP-A and SWB, respectively. Beta coefficients from the regression analyses indicated that secondary health conditions had the greatest negative impact on individuals' HRQoL (β_AQoL-8D = -0.668, β_EQ-5D-5L = -0.542), followed by SWB (β_SWB = -0.481) and capability wellbeing (β_ICECAP-A = -0.477). Capability wellbeing mediated the effect of secondary health conditions on HRQoL and SWB. The indirect effect of secondary health conditions on SWB through HRQoL was not statistically significant when using EQ-5D-5L; indirect effects were found when using AQoL-8D, one through HRQoL only and one through both capability wellbeing and HRQoL. This study highlights the different impacts of secondary health conditions on HRQoL, capability and SWB in the context of SCI. While the greatest impact was observed on individuals' HRQoL, our results provide further evidence that capability wellbeing (here, the ICECAP-A) adds complementary information about outcomes that could be used in economic evaluation.

Can Social Care Needs and Well-Being Be Explained by the EQ-5D? Analysis of the Health Survey for England

BACKGROUND

The recent shift to an integrated approach to health and social care aims to provide cohesive support to those who are in need of care, but raises a challenge for resource allocation decision making, in particular for comparison of diverse benefits from different types of care across the two sectors.

OBJECTIVE

To investigate the relationship of social care needs and well-being with a generic health status measure using multivariate regression.

METHODS

We empirically compared responses to health and well-being measures and social care needs from a cross-sectional data set of the general population (the Health Survey for England). Multivariate regression analyses were conducted to examine whether social care needs measured by the Barthel index can be explained by health status as captured by the EuroQol five-dimensional questionnaire (EQ-5D) and two well-being measures-the Warwick Edinburgh Mental Wellbeing Scale (WEMWBS) and the General Health Questionnaire (GHQ-12).

RESULTS

Our study found that poor overall scores for EuroQol visual analogue scale, EQ-5D index, GHQ-12, and WEMWBS indicated a need for social care. Investigation of the dimensions found that the EQ-5D dimensions self-care and pain/discomfort were statistically significantly associated with the need for social care. Two dimensions of the WEMWBS ("been feeling useful" and "had energy to spare") were statistically significantly associated with the Barthel index, but none of the GHQ-12 dimensions were.

CONCLUSIONS

The results show that the need for social care, which is dependent on the ability to perform personal day-to-day activities, is more closely related to the EQ-5D dimensions than the well-being measures WEMWBS and GHQ-12.

An Investigation of the Overlap Between the ICECAP-A and Five Preference-Based Health-Related Quality of Life Instruments

BACKGROUND

The ICEpop CAPability measure for Adults (ICECAP-A) is a measure of capability wellbeing developed for use in economic evaluations. It was designed to overcome perceived limitations associated with existing preference-based instruments, where the explicit focus on health-related aspects of quality of life may result in the failure to capture fully the broader benefits of interventions and treatments that go beyond health. The aim of this study was to investigate the extent to which preference-based health-related quality of life (HRQoL) instruments are able to capture aspects of capability wellbeing, as measured by the ICECAP-A.

METHODS

Using data from the Multi Instrument Comparison project, pairwise exploratory factor analyses were conducted to compare the ICECAP-A with five preference-based HRQoL instruments [15D, Assessment of Quality of Life 8-dimension (AQoL-8D), EQ-5D-5L, Health Utilities Index Mark 3 (HUI-3), and SF-6D].

RESULTS

Data from 6756 individuals were used in the analyses. The ICECAP-A provides information above that garnered from most commonly used preference-based HRQoL instruments. The exception was the AQoL-8D; more common factors were identified between the ICECAP-A and AQoL-8D compared with the other pairwise analyses.

CONCLUSION

Further investigations are needed to explore the extent and potential implications of 'double counting' when applying the ICECAP-A alongside health-related preference-based instruments.

Valuing health for oneself versus one's child or elderly parent

The aim of this study was to determine if adults value health states or are willing to accept risk differently for themselves than for their children or elderly parents. Participants (701) were asked to rate four hypothetical health states for themselves using both the standard gamble and time trade-off methodologies. They then did the same assessments for a real or hypothetical child as well as an elderly parent. Participants were willing to take more risk or trade more years of life to avoid bilateral vision loss and mental impairment for themselves than they were for their children and elderly parents.

Are Quality-Adjusted Life Years a Good Proxy Measure of Individual Capabilities?

BACKGROUND

There is a debate in the health economics literature concerning the most appropriate way of applying Amartya Sen's capability approach in economic evaluation studies. Some suggest that quality-adjusted life years (QALYs) alone are adequate while others argue that this approach is too narrow and that direct measures of capability wellbeing provide a more extensive application of Sen's paradigm.

OBJECTIVE

This paper empirically explores whether QALYs provide a good proxy for individual capabilities.

METHODS

Data is taken from a multinational cross-sectional survey of individuals with seven health conditions (asthma, arthritis, cancer, depression, diabetes, hearing loss, heart disease) and a healthy population. Each individual completed the ICECAP-A measure of capability wellbeing for adults and six health utility instruments that are used to generate QALYs, including EQ-5D and SF-6D. Primary analysis examines how well health utility instruments can explain variation in the ICECAP-A using ordinary least squares regression.

RESULTS

The findings show that all seven health conditions have a negative association on overall capability as measured by the ICECAP-A index. Inclusion of health utility instruments into separate regressions improves the predictive power of capability but on average, explains less than half of the variation in capability wellbeing. Individuals with arthritis appear to be less inhibited in terms of capability losses when accounting for health utility, yet those who have depression record significant reductions in capability relative to the healthy population even after accounting for the most commonly used health utility instruments.

CONCLUSION

The study therefore casts doubt on the ability of QALYs to act as a reliable proxy measure of individuals' capability.

Mapping Between the Sydney Asthma Quality of Life Questionnaire (AQLQ-S) and Five Multi-Attribute Utility Instruments (MAUIs)

PURPOSE

Economic evaluation of health services commonly requires information regarding health-state utilities. Sometimes this information is not available but non-utility measures of quality of life may have been collected from which the required utilities can be estimated. This paper examines the possibility of mapping a non-utility-based outcome, the Sydney Asthma Quality of Life Questionnaire (AQLQ-S), onto five multi-attribute utility instruments: Assessment of Quality of Life 8 Dimensions (AQoL-8D), EuroQoL 5 Dimensions 5-Level (EQ-5D-5L), Health Utilities Index Mark 3 (HUI3), 15 Dimensions (15D), and the Short-Form 6 Dimensions (SF-6D).

METHODS

Data for 856 individuals with asthma were obtained from a large Multi-Instrument Comparison (MIC) survey. Four statistical techniques were employed to estimate utilities from the AQLQ-S. The predictive accuracy of 180 regression models was assessed using six criteria: mean absolute error (MAE), root mean squared error (RMSE), correlation, distribution of predicted utilities, distribution of residuals, and proportion of predictions with absolute errors <0.0.5. Validation of initial 'primary' models was carried out on a random sample of the MIC data.

RESULTS

Best results were obtained with non-linear models that included a quadratic term for the AQLQ-S score along with demographic variables. The four statistical techniques predicted models that performed differently when assessed by the six criteria; however, the best results, for both the estimation and validation samples, were obtained using a generalised linear model (GLM estimator).

CONCLUSIONS

It is possible to predict valid utilities from the AQLQ-S using regression methods. We recommend GLM models for this exercise.

Does the EQ-5D capture the effects of physical and mental health status on life satisfaction among older people? A path analysis approach

PURPOSE

To examine the extent to which EQ-5D utility scores capture the effect of mental and physical health status on life satisfaction (LS) in older adults.

METHODS

Retrospective cohort study of 884 patients aged ≥70 years from 15 general practices in Ireland, including medical records, pharmacy claims, and self-completion questionnaire. Path analysis was used to evaluate the direct and indirect effects of: (1) chronic disease burden (based on medications data); (2) activity limitation (basic and instrumental activities of daily living); (3) anxiety symptoms and; (4) depressive symptoms (Hospital Anxiety and Depression Scale) on LS (Life Satisfaction Index Z), via a utility score based on responses to the EQ-5D scale. Utility scores were calculated using UK time trade-off utility weights. Covariates included age and socioeconomic status.

RESULTS

The final path model fitted the data well (goodness of fit χ² = 7.5, df (7), p = 0.37). The direct effects of chronic disease burden and disability on LS were not statistically significant and were excluded from the final model, indicating that EQ-5D score mediated 100% of the total effect on LS. The direct and indirect effects of anxiety and depression on LS were statistically significant, but the size of the indirect effect was small (4% of the total effect for anxiety and 6% of the total effect for depression).

CONCLUSION

The EQ-5D does not adequately capture the effects of anxiety and depression on LS among older adults, suggesting that it may lead to inaccurate assessments of the effectiveness of interventions in this cohort.

Life and health satisfaction in the adult population of Iran

OBJECTIVES

Increasing interest has emerged in the use of subjective well-being as a development indicator and for the evaluation of public policies. The aim of this study was to assess life and health satisfaction and their determinants in the adult population of Iran.

METHODS

We conducted a survey of a sample of 3,150 adults at least 18 years of age in Tehran, the capital of Iran. The subjects were selected using a stratified random sampling method, and they were interviewed face-to-face at their usual residence by trained interviewers. Life satisfaction was used as a measure of subjective well-being. We used ordinary least square regression models to assess the associations of life and health satisfaction with socio-demographic variables.

RESULTS

On a 0-10 scale, the mean (standard deviation) scores for life and health satisfaction were 6.93 (2.54) and 7.18 (1.97), respectively. The average score for life satisfaction in females was 0.52 points higher than in males. A U-shaped relationship was found between age and life satisfaction, with respondents 35 to 44 years of age having the lowest average level of life satisfaction. Satisfaction with life and health among divorced respondents was significantly lower than among never-married and married participants. The scores for life satisfaction in respondents who rated their health status as poor were 3.83 points lower than in those who rated their health status as excellent.

CONCLUSIONS

The majority of the population of Tehran was satisfied with their life and health. Self-rated health status had the greatest impact on life satisfaction.

Deriving population norms for the AQoL-6D and AQoL-8D multi-attribute utility instruments from web-based data

OBJECTIVES

(i) to demonstrate a method which ameliorates the problem of self-selection in the estimation of population norms from web-based data and (ii) to use the method to calculate population norms for two multi-attribute utility (MAU) instruments, the AQoL-6D and AQoL-8D, and population norms for the sub-scales from which they are constructed.

METHODS

A web-based survey administered the AQoL-8D MAU instrument (which subsumes the AQoL-6D questionnaire), to members of the public along with the AQoL-4D which has extant population norms. Age, gender and the AQoL-4D were used as post-stratification auxiliary variables to construct weights to ameliorate the potential effects of self-selection associated with web-based surveys. The weights were used to estimate unbiased population norms. Standard errors from the weighted samples were calculated using Jackknife estimation.

RESULTS

For both AQoL-6D and AQoL-8D, physical health dimensions decline significantly with age. In contrast, for the majority of the psycho-social dimensions there is a significant U-shaped profile. The net effect is a shallow U-shaped relationship between age and both the AQoL-6D and AQoL-8D utilities. This contrasts with the almost monotonic decline in the utilities derived from the AQoL-4D and SF-6D MAU instruments.

CONCLUSIONS

Post-stratification weights were used to ameliorate potential bias in the derivation of norms from web-based data for the AQoL-6D and AQoL-8D. The methods may be used generally to obtain norms when suitable auxiliary variables are available. The inclusion of an enlarged psycho-social component in the two instruments significantly alters the demographic profile.

Health state descriptions, valuations and individuals' capacity to walk: a comparative evaluation of preference-based instruments in the context of spinal cord injury

PURPOSE

This study explores variation in health state descriptions and valuations derived from preference-based health-related quality of life instruments in the context of spinal cord injury (SCI).

METHODS

Individuals living with SCI were invited to complete a web-based, cross-sectional survey. The survey comprised questions regarding demographics, SCI classifications and characteristics, secondary health complications and conditions, quality of life and SCI-specific functioning in activities of daily living. Four preference-based health status classification systems were included; Assessment of Quality of Life 8-dimension questionnaire (AQoL-8D), EQ-5D-5L, Health Utilities Index (HUI) and SF-6D (derived from the SF-36v2). In addition to descriptive comparisons of index scores and item/dimension responses, analyses explored dimension-level correlation and absolute agreement (intraclass correlation coefficient (ICC)). Subgroup analyses examined the influence of individuals' self-reported ability to walk.

RESULTS

Of 609 invitations, 364 (60 %) individuals completed the survey. Across instruments, convergent validity was seen between pain and mental health dimensions, while sizeable variation pertaining to issues of mobility was observed. Mean index scores were 0.248 (HUI-3), 0.492 (EQ-5D-5L), 0.573 (AQoL-8D) and 0.605 (SF-6D). Agreement ranged from 'slight' (HUI-3 and SF-6D; ICC = 0.124) to 'moderate' (AQoL-8D and SF-6D; ICC = 0.634). Walking status had a markedly different impact on health state valuations across instruments.

CONCLUSIONS

Variation in the way that individuals are able to describe their health state across instruments is not unique to SCI. Further research is necessary to understand the significant differences in index scores and, in particular, the implications of framing mobility-related questions in the context of respondents' ability to walk.

The relative importance of health, income and social relations for subjective well-being: An integrative analysis

There is much evidence that health, income and social relationships are important for our well-being, but little evidence on their relative importance. This study makes an integrative analysis of the relative influence of health related quality of life (HRQoL), household income and social relationships for subjective well-being (SWB), where SWB is measured by the first three of the five items on the satisfaction with life scale (SWLS). In a comprehensive 2012 survey from six countries, seven disease groups and representative healthy samples (N = 7933) reported their health along several measures of HRQoL. A Shapley value decomposition method measures the relative importance of health, income and social relationships, while a quantile regression model tests how the effects of each of the three predictors vary across different points of SWB distributions. Results are compared with the standard regression. The respective marginal contribution of social relationships, health and income to SWB (as a share of goodness-of-fit) is 50.2, 19.3 and 7.3% when EQ-5D-5L is used as a measure of health. These findings are consistent across models based on five alternative measures of HRQoL. The influence of the key determinants varied significantly between low and high levels of the SWB distribution, with health and income having stronger influence among those with relatively lower SWB. Consistent with several studies, income has a significantly positive association with SWB, but with diminishing importance.

Why do multi-attribute utility instruments produce different utilities: the relative importance of the descriptive systems, scale and 'micro-utility' effects

PURPOSE

Health state utilities measured by the major multi-attribute utility instruments differ. Understanding the reasons for this is important for the choice of instrument and for research designed to reconcile these differences. This paper investigates these reasons by explaining pairwise differences between utilities derived from six multi-attribute utility instruments in terms of (1) their implicit measurement scales; (2) the structure of their descriptive systems; and (3) 'micro-utility effects', scale-adjusted differences attributable to their utility formula.

METHODS

The EQ-5D-5L, SF-6D, HUI 3, 15D and AQoL-8D were administered to 8,019 individuals. Utilities and unweighted values were calculated using each instrument. Scale effects were determined by the linear relationship between utilities, the effect of the descriptive system by comparison of scale-adjusted values and 'micro-utility effects' by the unexplained difference between utilities and values.

RESULTS

Overall, 66 % of the differences between utilities was attributable to the descriptive systems, 30.3 % to scale effects and 3.7 % to micro-utility effects.

DISCUSSION

Results imply that the revision of utility algorithms will not reconcile differences between instruments. The dominating importance of the descriptive system highlights the need for researchers to select the instrument most capable of describing the health states relevant for a study.

CONCLUSIONS

Reconciliation of inconsistent utilities produced by different instruments must focus primarily upon the content of the descriptive system. Utility weights primarily determine the measurement scale. Other differences, attributable to utility formula, are comparatively unimportant.