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

Impact of secondary health conditions on the quality of life and wellbeing of Canadians living with spinal cord injury: A comparison of preference-weighted index scores derived from generic standardized instruments

CONTEXT/OBJECTIVES

To compare the assessment of the impact of secondary health conditions (SHCs) on the quality of life and wellbeing of Canadians living with spinal cord injury (SCI) using four preference-based outcome measures.

DESIGN

Secondary analysis of data from a cross-sectional, online survey.

SETTING

Community.

PARTICIPANTS

Community-dwelling adults (n = 364) living with traumatic or non-traumatic spinal cord injury at least one year post-injury (70% at least 10 years post-injury).

OUTCOME MEASURES

A modified version of the Spinal Cord Injury Secondary Conditions Scale (SCI-SCS); three health-related instruments (EQ-5D-5L, Health Utilities Index Mark 3 (HUI3), and the Assessment of Quality of Life 8-dimension questionnaire (AQoL-8D)) and a capability wellbeing instrument (ICEpop CAPability measure for Adults (ICECAP-A)).

RESULTS

Across unadjusted and controlled analyses (i.e. controlling for associations between index scores and sociodemographic and impairment characteristics), trends were observed that identified lower levels of quality of life/wellbeing with higher problem ratings for each of the SHCs. Despite the trends, there was considerable variation in mean index scores across instruments, with HUI3 scores the lowest of the health-related instruments and ICECAP-A scores the highest overall. Respiratory problems, depression/mood problems, pressure sores, and autonomic dysreflexia were associated with the lowest levels of quality of life and wellbeing.

CONCLUSIONS

Higher problem ratings for SHCs are negatively associated with scores derived from preference-based quality of life and wellbeing instruments. Variation in index scores across instruments - including across the health-related instruments alone - highlights the critical importance of assessing the relative merits of preference-based instruments when using (or considering using) these instruments/estimates in comparative effectiveness research and economic evaluation.

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.

A Comparison of Items and Constructs of Standardized Health-Related Quality of Life and Mental Well-Being Measures

OBJECTIVES

This study aimed to explore the internal constructs of the concepts being measured by EQ-5D-5L (a health-related quality of life measure that can produce preference-based utility values) and the 12-item General Health Questionnaire (GHQ-12, a mental well-being measure) and to understand to what extent the items of EQ-5D-5L and GHQ-12 associate with each other.

METHODS

We used data from 12 701 respondents participating in a Belgian survey in 2022. Correlation coefficients between GHQ-12 and EQ-5D-5L were calculated at both the aggregate and item levels. Multidimensional scaling, exploratory factor analysis, and regression models were performed to investigate the underlying constructs that are associated with the items.

RESULTS

Despite a moderate correlation (0.39) between the EQ-5D-5L and GHQ-12 total scores, only a trivial or weak correlation (<0.3) was observed between the first 4 EQ-5D-5L items and any GHQ-12 item. Multidimensional scaling and exploratory factor analysis showed the first 4 EQ-5D-5L dimensions were clustered together with EuroQol visual analog scale and positively phrased GHQ-12 items were close to each other, whereas EQ-anxiety/depression and negatively phrased GHQ-12 items were grouped with overall life satisfaction. In the regression models, not all GHQ-12 items had a significant coefficient to predict EQ-5D-5L responses.

CONCLUSIONS

To the best of our knowledge, we present the first comparison of items and underlying constructs of GHQ-12 and EQ-5D-5L. The results showed that GHQ-12 can only partially predict the responses of EQ-5D-5L and the 2 instruments measure different constructs. Researchers should carefully consider conceptual legitimacy while applying the mapping technique and consider sensitivity analyses for the mapping estimates.

The Broader Opportunity Costs in the Broader Cost-Effectiveness Analysis Framework

BACKGROUND

The traditional cost-effectiveness analysis framework usually takes a healthcare system perspective, where the aim is to maximise population health from a fixed budget allocated to healthcare. Extensions to this framework have been suggested, including: (i) incorporating impacts that fall outside the healthcare sector; (ii) accounting for outcomes beyond health; and (iii) assessing equity considerations. Several alternatives have been proposed that serve these purposes, for example, the extended "impact inventory", the "beyond-the-QALY" approach and the distributional cost-effectiveness analysis.

OBJECTIVE

This paper aims to develop a comprehensive framework that incorporates into the cost-effectiveness analysis framework some of its most advocated extensions and provides a means of arriving at a unidimensional cost-effectiveness analysis result measure.

METHODS

Building on previous work, I proposed a framework that explicitly incorporates the full extent of the opportunity costs that arise when new dimensions and distributional concerns are included in cost-effectiveness analyses. A hypothetical example is provided as a way of illustration.

RESULTS

Operationalising the proposed framework requires system-wide representative values and/or robust estimates concerning: (i) selecting dimensions; (ii) measuring opportunity costs associated with each dimension; (iii) quantifying equity weights and percentages of beneficiaries and losers meeting equity considerations; and (iv) attaching monetary values to dimensions measured using a non-monetary metric.

CONCLUSIONS

Extending the cost-effectiveness analysis framework entails extending the measurement of the opportunity costs of funding decisions. This implies populating an ambitious puzzle that in some cases poses fundamental conceptual and empirical questions. Potential routes of further research that might facilitate such undertaking are proposed.

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.

Where do measures of health, social care and wellbeing fit within a wider measurement framework? Implications for the measurement of quality of life and the identification of bolt-ons

BACKGROUND

There is variability across studies in the dimensionality i.e., set of latent variables to which health, social care and wellbeing measures relate. This variability may impact the development of new measures and the identification of bolt-on dimensions. We examine the dimensionality of commonly used measures and identify a set of potential bolt-ons for the EQ-5D-5L.

METHODS

We used the OMS dataset, an online survey of health, social care and wellbeing measures in patients and members of the general public. A content analysis provided a theoretical framework for results interpretation. Quantitative analyses were based on a pool of 79 items from 7 measures. Confirmatory factor analysis was used to assess health, social care and wellbeing measures dimensionality and their contribution to quality of life. The relationship between EQ-5D-5L items and the identified factors was used for bolt-ons identification.

RESULTS

The dimensionality comprised of seven factors, namely physical functioning, psychological symptoms, energy/sleep, physical pain, social functioning, needs and satisfaction. Health measures covered five of the seven factors identified, wellbeing measures three and the social care measure one. A list of candidate bolt-on items for the EQ-5D-5L was presented e.g., cognition, energy, dignity.

CONCLUSIONS

This study provides evidence on the dimensionality of health, social care and wellbeing measures and presents a list of candidate bolt-ons for the EQ-5D-5L.

An economic evaluation of an online computer-tailored smoking cessation intervention that includes message frame-tailoring: A randomized controlled trial

Evidence of economic evaluations of behaviour change interventions is scarce, but needed to guide policy makers' decision-making. This study economically evaluated 4 versions of an innovative online computer-tailored smoking cessation intervention. The economic evaluation from a societal perspective was embedded in a randomized controlled trial among 532 smokers using a 2 (message frame-tailoring, i.e. how messages are presented: autonomy-supportive vs controlling) x 2 (content-tailoring, i.e. what content is presented: tailored vs. generic) design. Both kinds of tailoring, content-tailoring and message frame-tailoring, were based on a set of questions asked at baseline. Self-reported costs, prolonged smoking abstinence (cost-effectiveness) and quality of life (cost-utility) were assessed during a 6-month-follow-up. For cost-effectiveness analysis, costs per abstinent smoker were calculated. For cost-utility analysis, costs per QALY (i.e. quality-adjusted life year) gained were calculated. A willingness-to-pay (WTP) threshold of €20.000 was used. Bootstrapping and sensitivity analysis were conducted. Cost-effectiveness analysis showed that up to a WTP of €2.000, the combination of message frame- and content-tailoring dominated all study groups. From a WTP of €2.005, the content-tailored group dominated all study groups. Cost-utility analysis revealed that the combination of message frame-tailoring and content-tailoring had the highest probability of being the most efficient study group at all levels of the WTP. The combination of message frame-tailoring and content-tailoring in online smoking cessation programmes seemed to have high potential for cost-effectiveness (smoking abstinence) and cost-utility (quality of life), thus providing good value for money. Yet, when the WTP for each abstinent smoker is high (i.e., €2.005 or higher), the addition of message frame-tailoring might not be worth the effort and content-tailoring only is preferred.

The ICEpop Capability Measure for Adults Instrument for Capabilities: Development of a Tariff for the Dutch General Population

OBJECTIVES

The ICEpop Capability Measure for Adults (ICECAP-A) assesses 5 capabilities (stability, attachment, autonomy, achievement, and enjoyment) that are important to one's quality of life and might be an important addition to generic health questionnaires currently used in economic evaluations. This study aimed to develop a Dutch tariff of the Dutch translation of the ICECAP-A.

METHODS

The methods used are similar to those used in the development of the UK tariff. A profile case best-worst scaling task was presented to 1002 participants from the general Dutch population. A scale-adjusted latent class analysis was performed to test for preferences of ICECAP-A capabilities and scale heterogeneity.

RESULTS

A 3-preference class 2-scale class model with worst choice as scale predictor was considered optimal and was used to calculate the resulting tariff. Results indicated that the capabilities stability, attachment, and enjoyment were considered more important aspects of quality of life than autonomy and achievement. Additionally, improving capabilities from low to moderate levels had a larger effect on quality of life than improving capabilities that were already at a higher level.

CONCLUSIONS

The ICECAP-A tariffs found in this study could be used in economic evaluations of healthcare interventions in The Netherlands.

Conceptualising 'Benefits Beyond Health' in the Context of the Quality-Adjusted Life-Year: A Critical Interpretive Synthesis

There is growing interest in extending the evaluative space of the quality-adjusted life-year framework beyond health. Using a critical interpretive synthesis approach, the objective was to review peer-reviewed literature that has discussed non-health outcomes within the context of quality-adjusted life-years and synthesise information into a thematic framework. Papers were identified through searches conducted in Web of Science, using forward citation searching. A critical interpretive synthesis allows for the development of interpretations (synthetic constructs) that go beyond those offered in the original sources. The final output of a critical interpretive synthesis is the synthesising argument, which integrates evidence from across studies into a coherent thematic framework. A concept map was developed to show the relationships between different types of non-health benefits. The critical interpretive synthesis was based on 99 papers. The thematic framework was constructed around four themes: (1) benefits affecting well-being (subjective well-being, psychological well-being, capability and empowerment); (2) benefits derived from the process of healthcare delivery; (3) benefits beyond the recipient of care (spillover effects, externalities, option value and distributional benefits); and (4) benefits beyond the healthcare sector. There is a wealth of research concerning non-health benefits and the evaluative space of the quality-adjusted life-year. Further dialogue and debate are necessary to address conceptual and normative challenges, to explore the societal willingness to sacrifice health for benefits beyond health and to consider the equity implications of different courses of action.

Performance of the EQ-5D-5L Plus Respiratory Bolt-On in the Birmingham Chronic Obstructive Pulmonary Disease Cohort Study

OBJECTIVES

A respiratory bolt-on dimension for the EQ-5D-5L has recently been developed and valued by the general public. This study aimed to validate the EQ-5D-5L plus respiratory dimension (EQ-5D-5L+R) in a large group of patients with chronic obstructive pulmonary disease (COPD).

METHODS

Validation was undertaken with data from the Birmingham COPD Cohort Study, a longitudinal UK study of COPD primary care patients. Data on the EQ-5D-5L+R were collected from 1008 responding participants during a follow-up questionnaire in 2017 and combined with (previously collected) data on patient and disease characteristics. Descriptive and correlation analyses were performed on the EQ-5D-5L+R dimensions and utilities, in relation to COPD characteristics and compared with the EQ-5D-5L without respiratory dimension. Multivariate regression models were estimated to test whether regression coefficients of clinical characteristics differed between the EQ-5D-5L+R utility and the EQ-5D-5L utility.

RESULTS

Correlation coefficients for the EQ-5D-5L+R utility with COPD parameters were slightly higher than the EQ-5D-5L utility. Both instruments displayed discriminant validity but analyses in clinical subgroups of patients showed larger absolute differences in utilities for the EQ-5D-5L+R. In the multivariate analyses, only the coefficient for the COPD Assessment Test score was higher for the model using the EQ-5D-5L+R utility as outcome.

CONCLUSIONS

This study showed that the addition of a respiratory domain to the EQ-5D-5L led to small improvements in the instrument's performance. Comparability of the EQ-5D across diseases, currently considered one of its strengths, would have to be traded off against a modest improvement in utility difference when adding the respiratory dimension.

The ICECAP-A instrument for capabilities: assessment of construct validity and test-retest reliability in a general Dutch population

PURPOSE

The ICEpop CAPability measure for Adults (ICECAP-A) assesses five capabilities that are important to one's well-being. The instrument might be an important addition to generic health questionnaires when evaluating quality of life extending beyond health. This study aimed to conduct a psychometric assessment of the Dutch translation of the ICECAP-A.

METHODS

Construct validity of the instrument was assessed in two ways. First, by measuring correlations with the EQ-5D-5L questionnaire and a measure of self-efficacy and, second, by investigating the ability to distinguish between groups known to differ on the construct the ICECAP-A means to capture. Additionally, test-retest reliability was evaluated.

RESULTS

In total, 1002 participants representative of the general Dutch population completed an online survey. For test-retest reliability, 252 participants completed the same questionnaire 2 weeks later. The ICECAP-A indicated moderate to strong correlations with the EQ-5D-5L and a strong correlation with self-efficacy. Furthermore, it was capable of differentiating known groups. Moreover, results indicated adequate test-retest reliability with an intraclass correlation coefficient of 0.79.

CONCLUSION

In summary, results suggest adequate test-retest reliability and construct validity and indicate that the ICECAP-A might be of added value, especially when considering areas outside of the traditional health intervention model.

Estimating the monetary value of health and capability well-being applying the well-being valuation approach

BACKGROUND

Quality of life measures going beyond health, like the ICECAP-A, are gaining importance in health technology assessment. The assessment of the monetary value of gains in this broader quality of life is needed to use these measurements in a cost-effectiveness framework.

METHODS

We applied the well-being valuation approach to calculate a first monetary value for capability well-being in comparison to health, derived by ICECAP-A and EQ-5D-5L, respectively. Data from an online survey administered in February 2018 to a representative sample of UK citizens aged 18-65 was used (N = 1512). To overcome the endogeneity of income, we applied an instrumental variable regression. Several alternative model specifications were calculated to test the robustness of the results.

RESULTS

The base case empirical estimate for the implied monetary value of a year in full capability well-being was £66,597. The estimate of the monetary value of a QALY, obtained from the same sample and using the same methodology amounted to £30,786, which compares well to previous estimates from the willingness to pay literature. Throughout the conducted robustness checks, the value of capability well-being was found to be between 1.7 and 2.6 times larger than the value of health.

CONCLUSION

While the applied approach is not without limitations, the generated insights, especially concerning the relative magnitude of valuations, may be useful for decision-makers having to decide based on economic evaluations using the ICECAP-A measure or, to a lesser extent, other (capability) well-being outcome measures.

Empirical Validity of a Generic, Preference-Based Capability Wellbeing Instrument (ICECAP-A) in the Context of Spinal Cord Injury

BACKGROUND

Assessing the validity of generic instruments across different clinical contexts is an important area of methodological research in economic evaluation and outcomes measurement.

OBJECTIVE

Our objective was to examine the empirical validity of a generic, preference-based capability wellbeing instrument (ICECAP-A) in the context of spinal cord injury.

METHODS

This study consisted of a secondary analysis of data collected using an online cross-sectional survey. The survey included questions regarding demographics, injury classifications and characteristics, secondary health conditions, quality of life and wellbeing, and functioning in activities of daily living. Analysis comprised the descriptive assessment of Spearman's rank correlations between item-/dimension-level data for the ICECAP-A and four preference-based health-related quality of life (HRQoL) instruments, and discriminant and convergent validity approaches to examine 21 evidence-informed or theoretically derived constructs. Constructs were defined using participant and injury characteristics and responses to a range of health, wellbeing and functioning outcomes.

RESULTS

Three hundred sixty-four individuals completed the survey. Mean index score for the ICECAP-A was 0.761; 12 (3%) individuals reported full capability (upper anchor; score = 1), and there were no reports of zero capabilities (lower anchor; score = 0). The strongest correlations were dominated by items and dimensions on the comparator (HRQoL) instruments that are non-health aspects of quality of life, such as happiness and control over one's life (including self-care). Of 21 hypothesised constructs, 19 were confirmed in statistical tests, the exceptions being the exploratory hypotheses regarding education and age at injury.

CONCLUSION

The ICECAP-A is an empirically valid outcome measure for assessing capability wellbeing in people with spinal cord injury living in a community setting. The extent to which the ICECAP-A provides complementary information to preference-based HRQoL instruments is dependent on the comparator.

Capability instruments in economic evaluations of health-related interventions: a comparative review of the literature

PURPOSE

Given increasing interest in using the capability approach for health economic evaluations and a growing literature, this paper aims to synthesise current information about the characteristics of capability instruments and their application in health economic evaluations.

METHODS

A systematic literature review was conducted to assess studies that contained information on the development, psychometric properties and valuation of capability instruments, or their application in economic evaluations.

RESULTS

The review identified 98 studies and 14 instruments for inclusion. There is some evidence on the psychometric properties of most instruments. Most papers found moderate-to-high correlation between health and capability measures, ranging between 0.41 and 0.64. ASCOT, ICECAP-A, -O and -SCM instruments have published valuation sets, most frequently developed using best-worst scaling. Thirteen instruments were originally developed in English and one in Portuguese; however, some translations to other languages are available. Ten economic evaluations using capability instruments were identified. The presentation of results show a lack of consensus regarding the most appropriate way to use capability instruments in economic evaluations with discussion about capability-adjusted life years (CALYs), years of capability equivalence and the trade-off between maximisation of capability versus sufficient capability.

CONCLUSION

There has been increasing interest in applying the capability-based approach in health economic evaluations, but methodological and conceptual issues remain. There is still a need for direct comparison of the different capability instruments and for clear guidance on when and how they should be used in economic evaluations.

Mapping the Minnesota Living with Heart Failure Questionnaire (MLHFQ) onto the Assessment of Quality of Life 8D (AQoL-8D) utility scores

PURPOSE

The Minnesota Living with Heart Failure Questionnaire (MLHFQ) is a widely used condition-specific measure of quality of life (QoL) in patients with heart failure. To use information from the MLHFQ in an economic evaluation, the MLHFQ must be mapped onto a preference-based measure of QoL. This study aims to develop a mapping algorithm between the MLHFQ and the Assessment of Quality of Life (AQoL) 8D utility instrument in patients with dilated cardiomyopathy (DCM).

METHODS

MLHFQ and AQoL-8D data were collected on 61 Australian adults with idiopathic DCM or other non-hypertrophic cardiomyopathies. Three statistical methods were used as follows: ordinary least squares (OLS) regression, the robust MM estimator, and the generalised linear models (GLM). Each included a range of explanatory variables. Model performance was assessed using key goodness-of-fit measures, the mean absolute error (MAE), and the root-mean-square error (RMSE).

RESULTS

The MLHFQ summary score and AQoL-8D utility scores were strongly correlated (r =  - 0.83, p < 0.0001) and the two subscales of the MLHFQ were correlated with the eight dimensions of the AQoL-8D. Utility scores were predicted with acceptable precision based on responses to the MLHFQ physical, emotional, social, and other subscales. OLS and GLM performed similarly with MAE and RMSE ranging 0.086-0.106 and 0.114-0.130, respectively.

CONCLUSION

The mapping algorithm developed in this study allows the derivation of AQoL-8D utilities from MLHFQ scores for use in cost-effectiveness analyses and most importantly, enables the economic evaluation of alternative heart failure therapy options when only the MLHFQ has been collected.

A Systematic Review of the Feasibility and Psychometric Properties of the ICEpop CAPability Measure for Adults and Its Use So Far in Economic Evaluation

OBJECTIVES

Development of the ICEpop CAPability measure for Adults (ICECAP-A) was reported in 2012; use of certain capability measures was suggested in the context of social or long-term care soon afterward by decision-making organizations in the United Kingdom and The Netherlands. Despite enthusiasm for the ICECAP-A, this study represents the first attempt to collate evidence on its psychometric properties and its use in economic analysis.

METHODS

A systematic review of studies published between January 2012 and February 2019 that have either explored the psychometric properties of the ICECAP-A (validity, reliability, and responsiveness) or report its use in economic analysis.

RESULTS

Twenty-seven studies were identified, 11 undertaking some form of economic analysis (including pilot and feasibility studies) and 16 assessing psychometric properties (7 assessing construct validity). The ICECAP-A has mainly been used in the United Kingdom, but also in other English-speaking countries and in Europe, across a wide range of healthcare contexts. There is promising evidence on content validity, construct validity, and responsiveness. Although there was consistently strong associations between the ICECAP-A and the Assessment of Quality of Life-Eight Dimension, associations with the EuroQol 5-dimension 3-level and EuroQol 5-dimension 5-level were inconsistent. In some cases, it was found that a switch in evaluative space from health to capability well-being would alter resource allocation decisions.

CONCLUSION

The ICECAP-A is correlated with health-related quality of life but is most appropriately regarded as a complement for and not a substitute to the EuroQol 5-dimension 3-level and EuroQol 5-dimension 5-level in particular. Positive evidence of the measure's content and construct validity is beginning to accumulate, but further conceptual and policy debate is needed regarding the equity implications of switching between evaluative spaces.

Test-retest reliability of ICECAP-A in the adult Danish population

PURPOSE

To investigate the test-retest reliability of Investigating Choice Experiments Capability measure for Adults (ICECAP-A) in the adult Danish population.

METHODS

The original English ICECAP-A was translated into Danish by forward-backwards translation using the guidelines by Beaton et al. Three hundred and-thirty-two participants with mean age of 57 years participated in a Web-based study. Data concerning relative and absolute agreement were analysed by the intra-class correlation coefficient and Bland-Altman plot with limits of agreement. The overall and item consistency was investigated by weighted kappa statistics from baseline to 2-week follow-up. Logistic regression was used to study the effect of the sociodemographic characteristics with inconsistent responses as the dependent binary variable. The independent variables were age, sex, education, income, and region of residence at baseline.

RESULTS

The baseline ICECAP-A preference-based index score was 0.84, and at follow-up, 0.83. The ICC was 0.86 (95% CI 0.826-0.884), and limits of agreement were 0.164 and - 0.151. The kappa coefficient ranges from 45 to 65%, between random and perfect agreement. The logistic regression to analyse inconsistent responses showed no significant association between the overall index score and sociodemographic characteristics, and no clear pattern was found concerning the individual item inconsistency.

CONCLUSIONS

Evidence regarding the reliability of the Danish version of ICECAP-A is satisfactory for both the index score agreement and the individual item consistency and is a reliable measure to be used in a Danish context and future health economic evaluations.

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.

Quantifying the Relationship between Capability and Health in Older People: Can't Map, Won't Map

BACKGROUND

Intuitively, health and capability are distinct but linked concepts. This study aimed to quantify the link between a measure of health status (EQ-5D-3L) and capability (ICECAP-O) using regression-based methods.

METHODS

EQ-5D-3L and ICECAP-O data were collected from a sample of older people ( n = 584), aged over 65 years, requiring a hospital visit and/or care home resident, and recruited to one of 3 studies forming the Medical Crisis in Older People (MCOP) program in England. The link of EQ-5D-3L with 1) ICECAP-O tariff scores were estimated using ordinary least squares (OLS) or censored least absolute deviation (CLAD) regression models; and 2) ICECAP-O domain scores was estimated using multinomial logistic (MNL) regression. Mean absolute error (MAE), root mean squared error (RMSE), absolute difference (AD) between mean observed and estimated values, and the R² statistic were used to judge model performance.

RESULTS

In this sample of older people ( n = 584), higher scores on the EQ-5D-3L were shown to be linked with higher ICECAP-O scores when using linear regression. An OLS-regression model was identified to be the best performing model with the lowest error statistics (AD = 0.0000; MAE = 0.1208; MSE = 0.1626) and highest goodness of fit ( R² = 0.3532); model performance was poor when predicting the lower ICECAP-O tariff scores. The three domains of the EQ-5D-3L showing a statistically significant quantifiable link with the ICECAP-O tariff score were self-care, usual activities, and anxiety/depression.

CONCLUSION

A quantifiable, but weak, link between health (EQ-5D-3L) and capability (ICECAP-O) was identified. The findings from this study add further support that the ICECAP-O is providing complimentary information to the EQ-5D-3L. Mapping between the 2 measures is not advisable and the measures should not be used as direct substitutes to capture the impact of interventions in economic evaluations.