OBJECTIVES To review, and to develop further, the methods used to assess and to increase the generalisability of economic evaluation studies. DATA SOURCES Electronic databases. REVIEW METHODS Methodological studies relating to economic evaluation in healthcare were searched. This included electronic searches of a range of databases, including PREMEDLINE, MEDLINE, EMBASE and EconLit, and manual searches of key journals. The case studies of a decision analytic model involved highlighting specific features of previously published economic studies related to generalisability and location-related variability. The case-study involving the secondary analysis of cost-effectiveness analyses was based on the secondary analysis of three economic studies using data from randomised trials. RESULTS The factor most frequently cited as generating variability in economic results between locations was the unit costs associated with particular resources. In the context of studies based on the analysis of patient-level data, regression analysis has been advocated as a means of looking at variability in economic results across locations. These methods have generally accepted that some components of resource use and outcomes are exchangeable across locations. Recent studies have also explored, in cost-effectiveness analysis, the use of tests of heterogeneity similar to those used in clinical evaluation in trials. The decision analytic model has been the main means by which cost-effectiveness has been adapted from trial to non-trial locations. Most models have focused on changes to the cost side of the analysis, but it is clear that the effectiveness side may also need to be adapted between locations. There have been weaknesses in some aspects of the reporting in applied cost-effectiveness studies. These may limit decision-makers' ability to judge the relevance of a study to their specific situations. The case study demonstrated the potential value of multilevel modelling (MLM). Where clustering exists by location (e.g. centre or country), MLM can facilitate correct estimates of the uncertainty in cost-effectiveness results, and also a means of estimating location-specific cost-effectiveness. The review of applied economic studies based on decision analytic models showed that few studies were explicit about their target decision-maker(s)/jurisdictions. The studies in the review generally made more effort to ensure that their cost inputs were specific to their target jurisdiction than their effectiveness parameters. Standard sensitivity analysis was the main way of dealing with uncertainty in the models, although few studies looked explicitly at variability between locations. The modelling case study illustrated how effectiveness and cost data can be made location-specific. In particular, on the effectiveness side, the example showed the separation of location-specific baseline events and pooled estimates of relative treatment effect, where the latter are assumed exchangeable across locations. CONCLUSIONS A large number of factors are mentioned in the literature that might be expected to generate variation in the cost-effectiveness of healthcare interventions across locations. Several papers have demonstrated differences in the volume and cost of resource use between locations, but few studies have looked at variability in outcomes. In applied trial-based cost-effectiveness studies, few studies provide sufficient evidence for decision-makers to establish the relevance or to adjust the results of the study to their location of interest. Very few studies utilised statistical methods formally to assess the variability in results between locations. In applied economic studies based on decision models, most studies either stated their target decision-maker/jurisdiction or provided sufficient information from which this could be inferred. There was a greater tendency to ensure that cost inputs were specific to the target jurisdiction than clinical parameters. Methods to assess generalisability and variability in economic evaluation studies have been discussed extensively in the literature relating to both trial-based and modelling studies. Regression-based methods are likely to offer a systematic approach to quantifying variability in patient-level data. In particular, MLM has the potential to facilitate estimates of cost-effectiveness, which both reflect the variation in costs and outcomes between locations and also enable the consistency of cost-effectiveness estimates between locations to be assessed directly. Decision analytic models will retain an important role in adapting the results of cost-effectiveness studies between locations. Recommendations for further research include: the development of methods of evidence synthesis which model the exchangeability of data across locations and allow for the additional uncertainty in this process; assessment of alternative approaches to specifying multilevel models to the analysis of cost-effectiveness data alongside multilocation randomised trials; identification of a range of appropriate covariates relating to locations (e.g. hospitals) in multilevel models; and further assessment of the role of econometric methods (e.g. selection models) for cost-effectiveness analysis alongside observational datasets, and to increase the generalisability of randomised trials.

Generalisability in economic evaluation studies in healthcare: a review and case studies.

The EORTC QLQ-C30 Health-Related Quality of Life (HRQOL) questionnaire was completed by 3069/3919 (78%) of a random sample of the Swedish population aged 18-79 years. The aims of the study were to provide normative data on the questionnaire and to investigate differences in HRQOL with respect to age, gender, sociodemographic characteristics and reported chronic health problems. Women had lower scores than men on all but one of the EORTC QLQ-C30 subscales and reported more chronic health problems. The oldest respondents (70-79 years) had a greater degree of impaired HRQOL than the other age groups, with one exception, 'Emotional functioning', in which they scored higher. Unemployed respondents reported poorer HRQOL than employed respondents. Higher income was associated with a more positive assessment of HRQOL. The results of the study present reference values for EORTC QLQ-C30 Version 3 questionnaire and clarify the influence of factors which should be taken into account when planning studies of HRQOL.

Health-related Quality of Life Measured by the EORTC QLQ-C30 Reference Values From a Large Sample of the Swedish Population

PURPOSE: This study investigated (1) the attitudes of cancer patients toward discussing health-related quality-of-life (HRQL) issues; (2) the association between such attitudes and patients’ characteristics; and (3) oncologists’ attitudes and self-reported behavior regarding these same issues. PATIENTS AND METHODS: Two hundred seventy-three patients receiving palliative chemotherapy and ten physicians were asked to complete a series of questionnaires. RESULTS: Almost all patients wanted to discuss their physical symptoms and physical functioning and were also willing to address their emotional functioning and daily activities. However, 25% of the patients were only willing to discuss these latter two issues at the initiative of their physician. Patients varied most in their willingness to discuss their family and social life, with 20% reporting no interest in discussing these issues at all. Female patients were more reluctant to discuss various HRQL issues than male patients. Older and less well-educated ...

How Are You Feeling? Who Wants To Know? Patients’ and Oncologists’ Preferences for Discussing Health-Related Quality-of-Life Issues

Velarde-Jurado E, Avila-Figueroa C. Methods for quality of life assessment. Salud Publica Mex 2002;44:349-361. The English version of this paper is available at: http://www.insp.mx/salud/index.html Abstract This paper reviews the methods and principles for quality of life assessment. The aging of the population and the im- proved survival of people with acute and chronic condi- tions have produced several levels of disability requiring long-term treatment and rehabilitation. In 1948 the World Health Organization defined health as not merely the ab- sence of disease but rather a state of complete physical, mental, and social well being. This term evolved from its conceptual definition to the development of scales to mea- sure the quality of life beyond physical status. Thus, quality of life assessment includes areas such as mental health, so- cial support, and life satisfaction. It is recognized that the expectations, vitality, pain, disability, and personal experien- ces influence the perception of a person's general health. A composite measurement aimed to quantify health accord- ing to physical, mental, and social well being simultaneously would likely find people at different points on the three different continua, but in the midranges of the composite. The multidimensionality problems and the level of subjec- tivity involved in the assessment of the quality of life re- quire valid and reliable instruments. This paper present an inventory of 126 questionnaires aimed to measure the quality of life for several diseases and populations. A better under- standing of the methods to assess the quality of life will allow the incorporation of these instruments in the com- prehensive assessment of patients, into clinical trials, and for health services research. The English version of this pa- per is available at: http://www.insp.mx/salud/index.html

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Evaluación de la calidad de vida

Although numerous paediatric-based health-related quality-of-life (HR-QOL) instruments are currently in use, there still remain conceptual, methodological and developmental issues to address. This paper provides an up-to-date critical review of the HR-QOL literature in paediatric medicine. Our analysis indicates that there is no consensus on how HR-QOL and overall QOL should be defined and measured in children. It is recommended that future studies focus on operationalising and distinguishing these constructs from each other and from traditional health-status measures. A clear empirical basis for generating instrument items and for prioritising specific domains must be described. Researchers should consider using the data gathered during their first interviews as a springboard from which to test their ideas of HR-QOL and QOL, reformulate concepts and subsequently retest their notions before developing instruments. Related to methodological challenges, consistency and agreement are still used interchangeably when comparing child and parent reports of children’s HR-QOL. The Pearson correlation is a measure of co-variation in scores, and not a measure of agreement. We recommend that researchers focus on determining agreement as opposed to consistency. Few, if any, attempts have been made to account for the possibility that a response shift may have occurred in the evaluation of HR-QOL. Most studies have compared HR-QOL scores of children with illness with their healthy peers. As such, there is a dearth of knowledge regarding the normative process of adaptation within the context of illness. It is recommended that researchers focus on gathering data using a relative standard of comparison. We further recommend that researchers interpret HR-QOL data in line with their intended purpose. Regarding developmental consideration, particular attention ought to be paid to developing instruments that consider children’s emerging sense of self, cognitive capacity and emotional awareness. Instruments that include items that are age appropriate are more likely to maximise reliability and validity of reports. The results of many HR-QOL instruments are applied in pharmacotherapeutic and pharmacoeconomic assessments. However, there has been relative infrequent application of economically valid HR-QOL tools (utility scales) and the use of HR-QOL scales as outcome measures in paediatric drug trials. As such, few cost-utility analyses have been performed to inform paediatric decision making. In addition, many of the concerns in the development of HR-QOL instruments should also be applied to the utility scales such that they reflect adequately children’s preferences for health states.

Evaluating health-related quality-of-life studies in paediatric populations: some conceptual, methodological and developmental considerations and recent applications.

N Neymark

Papers

Methodological and Statistical Issues of Quality of Life (QoL) and Economic Evaluation in Cancer Clinical Trials: Report of a Workshop

The costs of managing patients with advanced colorectal cancer in 10 different European centres.