Aimee Maxwell

Validity and Reliability of the Assessment of Quality of Life (AQoL)-8D Multi-Attribute Utility Instrument

ObjectiveThe purpose of this paper was to report tests of the validity and reliability of a new instrument, the Assessment of Quality of Life (AQoL)-8D, which was constructed to improve the evaluation of health services that have an impact upon the psychosocial aspects of the quality of life.MethodsAustralian and US data from a large multi-instrument comparison survey were used to conduct tests of convergent, predictive and content validity using as comparators five other multi-attribute utility (MAU) instruments—the EQ-5D, SF-6D, Health Utilities Index (HUI) 3, 15D and the Quality of Well-Being (QWB)—as well as four non-utility instruments—the SF-36 and three measures of subjective well-being (SWB). A separate three part Australian survey was used to assess test–retest reliability.ResultsResults indicate that AQoL-8D correlates more highly with both the SWB instruments and the psychosocial dimensions of the SF-36, and that it is similar to the other MAU instruments in terms of its convergent and predictive validity. The second Australian survey demonstrated high test–retest reliability.ConclusionsThe results indicate that the AQoL-8D is a reliable and valid instrument which offers an alternative to the MAU instruments presently used in economic evaluation studies, and one which is particularly suitable when psychosocial elements of health are of importance.

Comparing and Explaining Differences in the Magnitude, Content, and Sensitivity of Utilities Predicted by the EQ-5D, SF-6D, HUI 3, 15D, QWB, and AQoL-8D Multiattribute Utility Instruments

Background. Cost utility analysis permits the comparison of disparate health services by measuring outcomes in comparable units, namely, quality-adjusted life-years, which equal life-years times the utility of the health state. However, comparability is compromised when different utility instruments predict different utilities for the same health state. The present paper measures the extent of, and reason for, differences between the utilities predicted by the EQ-5D-5L, SF-6D, HUI 3, 15D, QWB, and AQoL-8D. Methods. Data were obtained from patients in seven disease areas and members of the healthy public in six countries. Differences between public and patient utilities were estimated using each of the instruments. To explain discrepancies between the estimates, the measurement scales and content of the instruments were compared. The sensitivity of instruments to independently measured health dimensions was measured in pairwise comparisons of all combinations of the instruments. Results. The difference between public and patient utilities varied with the choice of instrument by more than 50% for every disease group and in four of the seven groups by more than 100%. Discrepancies were associated with differences in both the instrument content and their measurement scales. Pairwise comparisons of instruments found that variation in the sensitivity to physical and psychosocial dimensions of health closely reflected the items in the instruments descriptive systems. Discussion. Results indicate that instruments measure related but different constructs. They imply that commonly used instruments systematically discriminate against some classes of services, most notably mental health services. Differences in the instrument scales imply the need for transformations between the instruments to increase the comparability of measurement.

Measuring the Sensitivity and Construct Validity of 6 Utility Instruments in 7 Disease Areas

Background. Health services that affect quality of life (QoL) are increasingly evaluated using cost utility analyses (CUA). These commonly employ one of a small number of multiattribute utility instruments (MAUI) to assess the effects of the health service on utility. However, the MAUI differ significantly, and the choice of instrument may alter the outcome of an evaluation. Aims. The present article has 2 objectives: 1) to compare the results of 3 measures of the sensitivity of 6 MAUI and the results of 6 tests of construct validity in 7 disease areas and 2) to rank the MAUI by each of the test results in each disease area and by an overall composite index constructed from the tests. Methods. Patients and the general public were administered a battery of instruments, which included the 6 MAUI, disease-specific QoL instruments (DSI), and 6 other comparator instruments. In each disease area, instrument sensitivity was measured 3 ways: by the unadjusted mean difference in utility between public and patient groups, by the value of the effect size, and by the correlation between MAUI and DSI scores. Content and convergent validity were tested by comparison of MAUI utilities and scores from the 6 comparator instruments. These included 2 measures of health state preferences, measures of subjective well-being and capabilities, and generic measures of physical and mental QoL derived from the SF-36. Results. The apparent sensitivity of instruments varied significantly with the measurement method and by disease area. Validation test results varied with the comparator instruments. Notwithstanding this variability, the 15D, AQoL-8D, and the SF-6D generally achieved better test results than the QWB and EQ-5D-5L.

Maximising health versus sharing: Measuring preferences for the allocation of the health budget

Empirical evidence indicates that people consider sharing health resources to be important even in the absence of the attributes usually associated with equity (age, social class, ethnicity, disease severity or geographic location). If government is to take account of these preferences then survey methods are needed which allow their measurement. The present paper presents a new technique for measuring these preferences and reports the results of a representative survey of 626 Australians which employed the technique. The online and postal survey did not include any of the attributes usually associated with equity but was designed to quantify the respective importance of sharing life years (outcome egalitarianism), resource sharing per se and the changing importance of total health as other attributes varied. Results indicate respondents were primarily concerned with outcome egalitarianism, and that cost per life year had a relatively small effect upon their allocative decisions.

Emotional demands, emotional labour and occupational outcomes in school principals Modelling the relationships

Most research into emotional labour is focussed on front-line service staff and health professionals, in short-term interactions. Little exists exploring the emotional labour involved in repeated on-going interactions by educational leaders with key stakeholders. This study explored the relationships between emotional demands, three emotional labour facets, burnout, wellbeing and job satisfaction in 1320 full-time school principals. Principals displayed significantly higher scores on emotional demands at work, burnout and job satisfaction, and significantly lower wellbeing scores than the general population. Structural equation modelling revealed that emotional demands predicted the elevated use of all emotional labour strategies. Surface Acting-Hiding emotions had an inverse relationship with burnout, wellbeing and job satisfaction. Surface Acting-Faking emotions had an inverse relationship with job satisfaction. Deep Acting demonstrated no significant associations with outcome variables. The findings of this study extend the current literature on the effects of emotional labour. The study also extends understanding about the separate effects of the facets of emotional labour, which will aid in the development of interventions to reduce high levels of burnout reported by educational leaders.

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.MethodsA 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.ResultsFor 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.ConclusionsPost-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.

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

PurposeEconomic 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).MethodsData 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.ResultsBest 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).ConclusionsIt is possible to predict valid utilities from the AQLQ-S using regression methods. We recommend GLM models for this exercise.

Communal Sharing and the Provision of Low-Volume High-Cost Health Services: Results of a Survey

IntroductionThis paper suggests and tests a reason why the public might support the funding of services for rare diseases (SRDs) when the services are effective but not cost effective, i.e. when more health could be produced by allocating funds to other services. It is postulated that the fairness of funding a service is influenced by a comparison of the average patient benefit with the average cost to those who share the cost.MethodsSurvey respondents were asked to allocate a budget between cost-effective services that had a small effect upon a large number of relatively well patients and SRDs that benefited a small number of severely ill patients but were not cost effective because of their high cost.ResultsPart of the budget was always allocated to the SRDs. The budget share rose with the number sharing the cost.DiscussionSharing per se appears to characterise preferences. This has been obscured in studies that focus upon cost per patient rather than cost per person sharing the cost.

Age Weights for Health Services Derived from the Relative Social Willingness to Pay Instrument

The effect of a patient’s age on the social valuation of health services remains controversial, with empirical results varying in magnitude and implying a different age-value profile. This article employs a new methodology to re-examine these questions. Data were obtained from 2 independent Web-based surveys that administered the Relative Social Willingness to Pay instrument. In the first survey, the age of the patient receiving a life-saving service was varied. Patients were left with either poor mental or physical health. In the second survey, patient age was varied for a service that fully cured the patient’s poor mental or physical health. In total, therefore, 4 sets of age weights were obtained: weights for life-extending services with poor physical or mental health outcomes and weights for quality-of-life improvement for patients in poor mental or physical health. Results were consistent. Increasing age was associated in each case with a monotonic decrease in the social valuation of the services. The decrease in value was quantitatively small until age 60 years. By age 80 years, the social value of services had declined by about 50%. The decline commenced at an earlier age in the context of physical health, although the magnitude of the decrement by age 80 years was unrelated to the type of service. With 1 exception, there was little difference in the valuation of services by the age of the survey respondent. Respondents aged >60 years placed a lower, not higher, value on quality-of-life improvement for elderly individuals than other respondents. There was no difference in the valuation of life-extending services.

How important is severity for the evaluation of health services: new evidence using the relative social willingness to pay instrument

The ‘severity hypothesis’ is that a health service which increases a patient’s utility by a fixed amount will be valued more highly when the initial health state is more severe. Supporting studies have employed a limited range of analytical techniques and the objective of the present paper is to test the hypothesis using a new methodology, the Relative Social Willingness to Pay. Three subsidiary hypotheses are: (1) that the importance of the ‘severity effect’ varies with the type of medical problem; (2) that the relationship between value and utility varies with the severity of the initial health state; and (3) that there is a threshold beyond which severity effects are insignificant. For each of seven different health problems respondents to a web-based survey were asked to allocate a budget to five services which would, cumulatively, move a person from near death to full health. The time trade-off utilities of health states before and after the service were estimated. The social valuation of the service measured by the budget allocation was regressed upon the corresponding increase in utility and severity as measured by the pre-service health state utility. Results confirm the severity hypothesis and support the subsidiary hypotheses. However, the effects identified are quantitatively significant only for the most severe health states. This implies a relatively limited redistribution of resources from those with less severe to those with more severe health problems.