Showing papers in "Health Economics in 2005"
TL;DR: It is demonstrated that multiple regression methods can be usefully applied to generate appropriate estimates of differential mean QALYs and an associated measure of sampling variability, while controlling for differences in baseline mean utility between treatment arms in the trial.
Abstract: In trial-based cost-effectiveness analysis baseline mean utility values are invariably imbalanced between treatment arms. A patient's baseline utility is likely to be highly correlated with their quality-adjusted life-years (QALYs) over the follow-up period, not least because it typically contributes to the QALY calculation. Therefore, imbalance in baseline utility needs to be accounted for in the estimation of mean differential QALYs, and failure to control for this imbalance can result in a misleading incremental cost-effectiveness ratio. This paper discusses the approaches that have been used in the cost-effectiveness literature to estimate absolute and differential mean QALYs alongside randomised trials, and illustrates the implications of baseline mean utility imbalance for QALY calculation. Using data from a recently conducted trial-based cost-effectiveness study and a micro-simulation exercise, the relative performance of alternative estimators is compared, showing that widely used methods to calculate differential QALYs provide incorrect results in the presence of baseline mean utility imbalance regardless of whether these differences are formally statistically significant. It is demonstrated that multiple regression methods can be usefully applied to generate appropriate estimates of differential mean QALYs and an associated measure of sampling variability, while controlling for differences in baseline mean utility between treatment arms in the trial.
791 citations
TL;DR: When the health sector variable whose inequality is being investigated is binary, the minimum and maximum possible values of the concentration index are equal to micro-1 and 1-micro, respectively, where micro is the mean of the variable in question.
Abstract: When the health sector variable whose inequality is being investigated is binary, the minimum and maximum possible values of the concentration index are equal to micro-1 and 1-micro, respectively, where micro is the mean of the variable in question. Thus as the mean increases, the range of the possible values of the concentration index shrinks, tending to zero as the mean tends to one and the concentration index tends to zero. Examples are presented on levels of and inequalities in immunization across 41 developing countries, and on changes in coverage and inequalities in selected countries.
556 citations
TL;DR: The inherent problems associated with applying dummy coding when including a fixed comparator in a discrete choice experiment are discussed, and the misinterpretations that may arise if the analyst is not aware of the problem are illustrated.
Abstract: This paper discusses the inherent problems associated with applying dummy coding when including a fixed comparator in a discrete choice experiment, and seeks to illustrate the misinterpretations that may arise if the analyst is not aware of the problem. This note provides two examples of possible misinterpretations with dummy coding and how it is solved with the use of effects coding.
542 citations
TL;DR: The NICE guidance on dealing with uncertainty is placed into a broader context of the requirements for decision making; the general approach that was taken in its development is explained; and each of the issues which have been raised in the debate about the role of probabilistic sensitivity analysis in general are addressed.
Abstract: Recently the National Institute for Clinical Excellence (NICE) updated its methods guidance for technology assessment. One aspect of the new guidance is to require the use of probabilistic sensitivity analysis with all cost-effectiveness models submitted to the Institute. The purpose of this paper is to place the NICE guidance on dealing with uncertainty into a broader context of the requirements for decision making; to explain the general approach that was taken in its development; and to address each of the issues which have been raised in the debate about the role of probabilistic sensitivity analysis in general. The most appropriate starting point for developing guidance is to establish what is required for decision making. On the basis of these requirements, the methods and framework of analysis which can best meet these needs can then be identified. It will be argued that the guidance on dealing with uncertainty and, in particular, the requirement for probabilistic sensitivity analysis, is justified by the requirements of the type of decisions that NICE is asked to make. Given this foundation, the main issues and criticisms raised during and after the consultation process are reviewed. Finally, some of the methodological challenges posed by the need fully to characterise decision uncertainty and to inform the research agenda will be identified and discussed.
460 citations
TL;DR: The results from a systematic review of the literature suggest that QALY maximisation is descriptively flawed, and the social value of a health improvement seems to be higher if the person has worse lifetime health prospects and higher if that person has dependents.
Abstract: In cost-utility analysis, the numbers of quality-adjusted life years (QALYs) gained are aggregated according to the sum-ranking (or QALY maximisation) rule. This requires that the social value from health improvements is a simple product of gains in quality of life, length of life and the number of persons treated. The results from a systematic review of the literature suggest that QALY maximisation is descriptively flawed. Rather than being linear in quality and length of life, it would seem that social value diminishes in marginal increments of both. And rather than being neutral to the characteristics of people other than their propensity to generate QALYs, the social value of a health improvement seems to be higher if the person has worse lifetime health prospects and higher if that person has dependents. In addition, there is a desire to reduce inequalities in health. However, there are some uncertainties surrounding the results, particularly in relation to what might be affecting the responses, and there is the need for more studies of the general public that attempt to highlight the relative importance of various key factors.
406 citations
TL;DR: This study uses the National Longitudinal Survey of Youth 1979 cohort to test several hypotheses about the robustness of the depression-income relationship among adults, and fixed-effects estimates and Instrumental variable estimates suggest that financial strain may not lead to depression.
Abstract: Prior studies have consistently found the incidence and persistence of depression to be higher among persons with low incomes, but causal mechanisms for this relationship are not well understood. This study uses the National Longitudinal Survey of Youth 1979 cohort to test several hypotheses about the robustness of the depression-income relationship among adults. In regressions of depression symptoms on income and sociodemographic variables, income is significantly associated with depression. However, when controls for other economic variables are included, the effect of income is considerably reduced, and generally not significant. Employment status and the ratio of debts-to-assets are both highly significant for men and for women both above and below the median income. Fixed-effects estimates suggest that employment status and financial strain are causally related to depression, but income is not. Instrumental variable estimates suggest that financial strain may not lead to depression.
361 citations
TL;DR: Italy's national health service is statutorily required to guarantee the uniform provision of comprehensive care throughout the country, but this is complicated by the fact that responsibility for health care is shared between the central government and the 20 regions.
Abstract: Italy's national health service is statutorily required to guarantee the uniform provision of comprehensive care throughout the country. However, this is complicated by the fact that, constitutionally, responsibility for health care is shared between the central government and the 20 regions. There are large and growing differences in regional health service organisation and provision. Public health-care expenditure has absorbed a relatively low share of gross domestic product, although in the last 25 years it has consistently exceeded central government forecasts. Changes in payment systems, particularly for hospital care, have helped to encourage organisational appropriateness and may have contributed to containing expenditure. Tax sources used to finance the Servizio Sanitario Nazionale (SSN) have become somewhat more regressive. The limited evidence on vertical equity suggests that the SSN ensures equal access to primary care but lower income groups face barriers to specialist care. The health status of Italians has improved and compares favourably with that in other countries, although regional disparities persist.
284 citations
TL;DR: In this article, the authors analyzed the effect of price regulation on delays in launch of new drugs in 25 major markets, including 14 EU countries, of 85 new chemical entities (NCEs) launched between 1994 and 1998.
Abstract: We analyze the effect of price regulation on delays in launch of new drugs. Because a low price in one market may 'spill-over' to other markets, through parallel trade and external referencing, manufacturers may rationally prefer longer delay or non-launch to accepting a relatively low price. We analyze the launch in 25 major markets, including 14 EU countries, of 85 new chemical entities (NCEs) launched between 1994 and 1998. Each NCE's expected price and market size in a country are estimated using lagged average price and market size of other drugs in the same (or related) therapeutic class. We estimate a Cox proportional hazard model of launch in each country, relative to first global launch. Only 55% of the potential launches occur. The US leads with 73 launches, followed by Germany (66) and the UK (64). Only 13 NCEs are launched in Japan, 26 in Portugal and 28 in New Zealand. The results indicate that countries with lower expected prices or smaller expected market size have fewer launches and longer launch delays, controlling for per capita income and other country and firm characteristics. Controlling for expected price and volume, country effects for the likely parallel export countries are significantly negative.
261 citations
TL;DR: Evidence was found that TTO values are not responsive in cases where 3 or more multiple complications are present, and therefore may underestimate utility loss for patients most adversely affected by complex chronic diseases like diabetes.
Abstract: Recent research has employed different analytical techniques to estimate the impact of the various long-term complications of type 2 diabetes on health-related utility and health status. However, limited patient numbers or lack of variety of patient experience has limited their power to discriminate between separate complications and grades of severity. In this study alternative statistical model forms were compared to investigate the influence of various factors on self-assessed health status and calculated utility scores, including the presence and severity of complications, and type of diabetes therapy. Responses to the EuroQol EQ-5D questionnaire from 4641 patients with type 2 diabetes in 5 European countries were analysed. Simple multiple regression analysis was used to model both visual analogue scale (VAS) scores and time trade-off index scores (TTO). Also, two complex models were developed for TTO analysis using a structure suggested by the EuroQol calculation algorithm. Both VAS and TTO models achieved greater explanatory power than in earlier studies. Relative weightings for individual complications differed between VAS and TTO scales, reflecting the strong influence of loss of mobility and severe pain in the EuroQol algorithm. Insulin-based therapy was uniformly associated with a detrimental effect equivalent to an additional moderate complication. Evidence was found that TTO values are not responsive in cases where 3 or more multiple complications are present, and therefore may underestimate utility loss for patients most adversely affected by complex chronic diseases like diabetes.
229 citations
TL;DR: Evidence is provided that the SF-6D is an empirically valid and efficient alternative multi-attribute utility measure to the EQ-5D, and is capable of discriminating between external indicators of health status, which should be considered when selecting either measure for evaluative purposes.
Abstract: Background: An important consideration for studies that derive utility scores using multi-attribute utility measures is the psychometric integrity of the measurement instrument. Of particular importance is the requirement to establish the empirical validity of multi-attribute utility measures; that is, whether they generate utility scores that, in practice, reflect people's preferences. We compared the empirical validity of EQ-5D versus SF-6D utility scores based on hypothetical preferences in a large, representative sample of the English population.
Methods: Adult participants in the 1996 Health Survey for England (n=16 443) formed the basis of the investigation. The subjects were asked to complete the EQ-5D and SF-36 measures. Their responses were converted into utility scores using the York A1 tariff set and the SF-6D utility algorithm, respectively. One-way analysis of variance was used to test the hypothetically constructed preference rule that each set of utility scores differs significantly by self-reported health status (categorised as very good, good, fair, bad or very bad). The degree to which EQ-5D and SF-6D utility scores reflect alternative configurations of self-reported health status; illness, disability or infirmity, and medication use was tested using the relative efficiency statistic and receiver operating characteristic (ROC) curves.
Results: The mean utility score for the EQ-5D was 0.845 (95% CI: 0.842, 0.849), whilst the mean utility score for the SF-6D was 0.799 (95% CI: 0.797, 0.802), representing a mean difference in utility score of 0.046 (95% CI: 0.044, 0.049; p<0.001). Bland–Altman plots displayed considerable lack of agreement between the two measures, particularly at the lower end of the utility scale. Both measures demonstrated statistically significant differences between subjects who described their health status as very good, good, fair, bad or very bad (p<0.001), as well as monotonically decreasing utility scores (test for linear trend: p<0.001). The SF-6D was between 30.9 and 100.4% more efficient than the EQ-5D at detecting differences in self-reported health status, and between 10.4 and 45.6% more efficient at detecting differences in illness, disability or infirmity and medication use. The area under the curve scores generated by the ROC curves were significantly higher for the SF-6D at the 0.1% significance level when self-reported health status was dichotomised as very good versus good, fair, bad or very bad. However, the AUC scores did not reveal any significant differences in the discriminatory powers of the measures when alternative configurations of illness, disability or infirmity and medication use were examined.
Conclusions: This study provides evidence that the SF-6D is an empirically valid and efficient alternative multi-attribute utility measure to the EQ-5D, and is capable of discriminating between external indicators of health status. However, health economists should also consider other psychometric properties, such as practicality and reliability, when selecting either measure for evaluative purposes. Copyright © 2005 John Wiley & Sons, Ltd.
180 citations
TL;DR: Some options for future health system reform include focusing on coordinating funding by developing a monopsony purchaser with the aim of improving quality of services and efficiency in the health system and changing provider incentives to improve productivity.
Abstract: The Greek health system does not yet offer universal coverage and has fragmented funding and delivery. Funding is regressive, with a reliance on informal payments, and there are inequities in access, supply and quality of services. Inefficiencies arise from an over reliance on relatively expensive inputs, as evidenced by the oversupply of specialists and under-supply of nurses. Resource allocation mechanisms are historical and political with no relation to performance or output, therefore providers have little incentive to improve productivity. Some options for future health system reform include focusing on coordinating funding by developing a monopsony purchaser with the aim of improving quality of services and efficiency in the health system and changing provider incentives to improve productivity.
TL;DR: This paper examines the link between price regulation and pharmaceutical research and development (R&D) investment and identifies two mechanisms through which price regulation may exert an influence on R&D: an expected-profit effect and a cash-flow effect.
Abstract: This paper examines the link between price regulation and pharmaceutical research and development (RD therefore, these issues are also discussed.
TL;DR: Using NLSY data, it is shown that one standard deviation increase in cognitive ability is associated with roughly the same increase in health as two years of schooling and that cognitive ability accounts for roughly one quarter of the association between schooling and health.
Abstract: A large literature documents a strong correlation between health and educational outcomes. In this paper we investigate the role of cognitive ability in the health-education nexus. Using NLSY data, we show that one standard deviation increase in cognitive ability is associated with roughly the same increase in health as two years of schooling and that cognitive ability accounts for roughly one quarter of the association between schooling and health. Both schooling and ability are strongly associated with health at low levels but less related or unrelated at high levels. Estimates treating schooling as endogenous to health suggest that much of the correlation between schooling and health is attributable to unobserved heterogeneity; the causal effect of schooling on health is large only for respondents with low levels of schooling and low cognitive ability. An implication is that policies which increase schooling will only increase health to the extent that they increase the education of poorly-educated individuals. Subsidies to college education, for example, are unlikely to increase population health.
TL;DR: Although considerable progress has been made in setting the appropriate stage for regulated competition in Dutch health care, the role of the market is still limited.
Abstract: In this paper we examine the goals and effects of health-care policy in the Netherlands over the period 1980--2000. During this period Dutch health-care policy is marked by a peculiar combination of increasingly stringent cost-containment policies alongside a persistent pursuit of market-oriented reforms. The main goal of cost containment was to keep labour costs down under the restriction of universal equal access to health care. Supply and price control policies were quite successful in achieving cost containment, but in due course prolonged quantity rationing began to jeopardise universal physical access to health services. The main goal of market-oriented health-care reforms is to increase the system's efficiency and its responsiveness to patient's needs, while maintaining equal access. The feasibility of the reforms crucially hinges on the realisation of adequate methods of risk adjustment, product classification and quality measurement, an appropriate consumer information system and an effective competition policy. Realising these preconditions requires a lengthy and cautious implementation process. Although considerable progress has been made in setting the appropriate stage for regulated competition in Dutch health care, the role of the market is still limited.
TL;DR: The technical quality of care, as represented by the thoroughness of examination, to be the most important quality attribute, followed by staff attitudes and drug availability, and the disutility of cost was found to decrease with higher socioeconomic status, as was the value of drug availability.
Abstract: This study reports on the results of a discrete choice experiment undertaken in Zambia to assess the factors influencing the demand for hospital care in Zambia, in particular the role of (perceived) quality and trade-offs between price and quality. Valuations of quality were evaluated for the treatment of two acute medical conditions, cerebral malaria in adults and acute pneumonia in children. Marginal utilities and willingness-to-pay for attributes of quality of hospital care were estimated, together with the influence of socioeconomic characteristics on these valuations and the extent of non-linearities in valuations of time and money. We find the technical quality of care, as represented by the thoroughness of examination, to be the most important quality attribute, followed by staff attitudes and drug availability. Valuations of examination thoroughness increase with increasing socioeconomic status. The disutility of cost was found to decrease with higher socioeconomic status, as was the value of drug availability. The implications of the findings for Zambian hospital sector reforms are discussed.
TL;DR: A coherent set of Bayesian methods to extend cost-effectiveness analyses to adjust for baseline covariates, to investigate differences between subgroups, and to allow for differences between centres in a multicentre study using a hierarchical model are proposed.
Abstract: Background: Overall assessments of cost–effectiveness are now commonplace in informing medical policy decision making. It is often important, however, also to investigate how cost–effectiveness varies between patient subgroups. Yet such analyses are rarely undertaken, because appropriate methods have not been sufficiently developed.
Methods: We propose a coherent set of Bayesian methods to extend cost–effectiveness analyses to adjust for baseline covariates, to investigate differences between subgroups, and to allow for differences between centres in a multicentre study using a hierarchical model. These methods consider costs and effects jointly, and allow for the typically skewed distribution of cost data. The results are presented as inferences on the cost–effectiveness plane, and as cost–effectiveness acceptability curves.
Results: In applying these methods to a randomised trial of case management of psychotic patients, we show that overall cost–effectiveness can be affected by ignoring the skewness of cost data, but that it may be difficult to gain substantial precision by adjusting for baseline covariates. While analyses of overall cost–effectiveness can mask important subgroup differences, crude differences between centres may provide an unrealistic indication of the true differences between them.
Conclusions: The methods developed allow a flexible choice for the distributions used for cost data, and have a wide range of applicability – to both randomised trials and observational studies. Experience needs to be gained in applying these methods in practice, and using their results in decision making. Copyright © 2005 John Wiley & Sons, Ltd.
TL;DR: Examination of health care reform in Spain along with empirical evidence on regional diversity, efficiency and inequality of these changes in the Spanish NHS suggest that besides significant heterogeneity, once region-specific needs are taken into account, there is evidence of efficiency improvements whilst inequalities in inputs and outcomes do not appear to have increased in the last decade.
Abstract: The consolidation of a universal health system coupled with a process of regional devolution characterise the institutional reforms of the National Health System (NHS) in Spain in the last two decades. However, scarce empirical evidence has been reported on the effects of changes in health inputs, outputs and outcomes, both at the country and at the regional level. This paper examines health care reform in Spain along with empirical evidence on regional diversity, efficiency and inequality of these changes in the Spanish NHS. Results suggest that besides significant heterogeneity, once region-specific needs are taken into account, there is evidence of efficiency improvements whilst inequalities in inputs and outcomes, although more 'visible', do not appear to have increased in the last decade. Therefore, the devolution process in the Spanish Health System offers an interesting case for the experimentation of health reforms related to regional diversity but compatible with the nature of a public NHS, with no sizeable regional inequalities.
TL;DR: This review of the TTO methodology used to elicit quality-of-life weights for own, current health shows that limiting cost-utility analysis to include only quality life weights from one method and one perspective is not enough to ensure that QALYs are comparable.
Abstract: A wide range of methods is used to elicit quality-of-life weights of different health states to generate 'Quality-adjusted life years' (QALYs). The comparability between different types of health outcomes at a numerical level is the main advantage of using a 'common currency for health' such as the QALY. It has been warned that results of different methods and perspectives should not be directly compared in QALY league tables. But do we know that QALYs are comparable if they are based on the same method and perspective?The Time trade-off (TTO) consists in a hypothetical trade-off between living shorter and living healthier. We performed a literature review of the TTO methodology used to elicit quality-of-life weights for own, current health. Fifty-six journal articles, with quality-of-life weights assigned to 102 diagnostic groups were included. We found extensive differences in how the TTO question was asked. The time frame varied from 1 month to 30 years, and was not reported for one-fourth of the weights. The samples in which the quality-of-life weights were elicited were generally small with a median size of 53 respondents. Comprehensive inclusion criteria were given for half the diagnostic groups. Co-morbidity was described in less than one-tenth of the groups of respondents. For two-thirds of the quality-of-life weights, there was no discussion of the influence of other factors, such as age, sex, employment and children. The different methodological approaches did not influence the TTO weights in a predictable or clear pattern. Whether or not it is possible to standardise the TTO method and the sampling procedure, and whether or not the TTO will then give valid quality-of-life weights, remains an open question.This review of the TTO elicited on own behalf, shows that limiting cost-utility analysis to include only quality life weights from one method and one perspective is not enough to ensure that QALYs are comparable.
TL;DR: In this article, a panel of Norwegian register data was used to analyze long-term sickness absences and found that the unemployment rate is negatively associated with the probability of absence, and with the number of days of sick leave.
Abstract: Sickness absence tends to be negatively correlated with unemployment rates. In addition to pure health effects, this may be due to moral hazard behavior by workers who are fully insured against income loss during sickness and to physicians who meet demand for medical certificates. Alternatively, it may reflect changes in the composition of the labor force, with more sickness-prone workers entering the labor force in upturns. A panel of Norwegian register data is used to analyze long-term sickness absences. The unemployment rate is shown to be negatively associated with the probability of absence, and with the number of days of sick leave. Restricting the sample to workers who are present in the whole sample period, the negative relationship between absence and unemployment becomes clearer. This indicates that procyclical variations in sickness absence are caused by established workers and not by the composition of the labor force.
TL;DR: Satisfaction of the tests was sensitive to normatively irrelevant factors such as the complexity of the task and demographic characteristics, which meant that a significant proportion of those individuals who 'failed' seem to have reformulated the experiment in some way in their mental process.
Abstract: Individuals' rationality has been a key issue long debated in Economics. While normative theories establish the way 'rational' consumers should behave, many empirical studies have documented numerous systematic violations of normative principles. This has led some to question the validity of classic economic models as an adequate approximation of individuals' real decision-making. This paper aims to shed more light on this debate. A stated preference choice experiment was set up to test rational choice properties. Attention was given to the extent to which satisfaction of such tests is related to both the complexity of the design, and subject characteristics. Quantitative and qualitative methods are applied. The majority of respondents passed the rationality tests. Satisfaction of the tests was sensitive to normatively irrelevant factors such as the complexity of the task and demographic characteristics. A significant proportion of those individuals who 'failed' seem to have reformulated the experiment in some way in their mental process. Implications for the design and analyses of future DCEs are discussed.
TL;DR: The QALY approach is recognisable as an application of the capability approach since it pays close attention to functionings, through the use of survey-based multi-attribute health state valuation instruments, and permits conceptions of value other than the traditional utilitarian ones of choice, desire-fulfilment and happiness.
Abstract: This explores the applicability of Sen's capability approach to the economic evaluation of health care programmes. An individual's 'capability set' describes his freedom to choose valuable activities and states of being ('functionings'). Direct estimation and valuation of capability sets is not feasible at present. Standard preference-based methods such as willingness to pay are feasible, but problematic due to the adaptive and constructed nature of individual preferences over time and under uncertainty. An alternative is to re-interpret the QALY as a cardinal and interpersonally comparable index of the value of the individual's capability set. This approach has limitations, since the link between QALYs and capabilities is not straightforward. Nevertheless, the QALY approach is recognisable as an application of the capability approach since it pays close attention to functionings, through the use of survey-based multi-attribute health state valuation instruments, and permits conceptions of value other than the traditional utilitarian ones of choice, desire-fulfilment and happiness. Furthermore, suitably re-interpreted, it can account for (i) non-separability between health and non-health components of value; and suitably modified it can also account for (ii) process attributes of care, which may have a direct effect on non-health functionings such as comfort and dignity, and (iii) sub-group diversity in the value of the same health functionings.
TL;DR: Results show a strong statistical relationship between drug spending and health outcomes, especially for infant mortality and life expectancy at 65, and this relationship is almost always stronger for private drug spending than for public drug spending.
Abstract: Canadian per capita drug expenditures increased markedly in recent years and have become center stage in the debate on health care cost containment. To inform public policy, these costs must be compared with the benefits provided by these drugs. This paper measures the statistical relationship between drug spending in Canadian provinces and overall health outcomes. The analysis relies on more homogenous data and includes a more complete set of controls for confounding factors than previous studies. Results show a strong statistical relationship between drug spending and health outcomes, especially for infant mortality and life expectancy at 65. This relationship is almost always stronger for private drug spending than for public drug spending. The analysis further indicates that substantially better health outcomes are observed in provinces where higher drug spending occurs. Simulations show that if all provinces increased per capita drug spending to the levels observed in the two provinces with the highest spending level, an average of 584 fewer infant deaths per year and over 6 months of increased life expectancy at birth would result.
TL;DR: In this paper, the labor supply of physicians employed at hospitals in Norway, using personnel register data merged with other public records, is estimated using a sample of 1303 male physicians observed over the period 1993-1997.
Abstract: Physicians are key personnel in a sector which is important due to its size as well as the quality of service it provides. We estimate the labor supply of physicians employed at hospitals in Norway, using personnel register data merged with other public records. A dynamic labor supply equation is estimated using a sample of 1303 male physicians observed over the period 1993-1997. The methods of estimation are GMM and system GMM. We reject the static model in favor of a dynamic model and obtain short run wage elasticities around 0.3. This is higher than previously estimated for physicians, in particular for those who are not self-employed.
TL;DR: The EM-algorithm with bootstrap, MI regression and MI MCMC are robust to the multivariate normal assumption and are the preferred methods for the analysis of incomplete cost data when the assumption of DCAR is not justified.
Abstract: Incomplete data due to premature withdrawal (dropout) constitute a serious problem in prospective economic evaluations that has received only little attention to date. The aim of this simulation study was to investigate how standard methods for dealing with incomplete data perform when applied to cost data with various distributions and various types of dropout. Selected methods included the product-limit estimator of Lin et al. the expectation maximisation (EM-) algorithm, several types of multiple imputation (MI) and various simple methods like complete case analysis and mean imputation. Almost all methods were unbiased in the case of dropout completely at random (DCAR), but only the product-limit estimator, the EM-algorithm and the MI approaches provided adequate estimates of the standard error (SE). The best estimates of the mean and SE for dropout at random (DAR) were provided by the bootstrap EM-algorithm, MI regression and MI Monte Carlo Markov chain. These methods were able to deal with skewed cost data in combination with DAR and only became biased when costs also included the costs of expensive events. None of the methods were able to deal adequately with informative dropout. In conclusion, the EM-algorithm with bootstrap, MI regression and MI MCMC are robust to the multivariate normal assumption and are the preferred methods for the analysis of incomplete cost data when the assumption of DCAR is not justified. Copyright © 2005 John Wiley & Sons, Ltd.
TL;DR: CVM is a promising alternative for existing methods like the opportunity cost method and the proxy good method to determine a monetary value of informal care that can be incorporated in the numerator of any economic evaluation.
Abstract: This paper reports the results of the application of the contingent valuation method (CVM) to determine a monetary value of informal care. We discuss the current practice in valuing informal care and a theoretical model of the costs and benefits related to the provision of informal care. In addition, we developed a survey in which informal caregivers' willingness to accept (WTA) to provide an additional hour of informal care was elicited. This method is better than normally recommended valuation methods able to capture the heterogeneity and dynamics of informal care. Data were obtained from postal surveys. A total of 153 informal caregivers and 149 care recipients with rheumatoid arthritis returned a completed survey. Informal caregivers reported a mean WTA to provide a hypothetical additional hour of informal care of 9.52 Euro (n=124). Many hypotheses derived from the theoretical model and the literature were supported by the data.CVM is a promising alternative for existing methods like the opportunity cost method and the proxy good method to determine a monetary value of informal care that can be incorporated in the numerator of any economic evaluation.
TL;DR: In this article, the authors used multilevel modelling to obtain more appropriate estimates of the population average incremental cost-effectiveness and associated standard errors compared to standard stochastic CEA.
Abstract: Cost-effectiveness analysis (CEA) in health care is increasingly conducted alongside multicentre and multinational randomised controlled clinical trials (RCTs). The increased use of stochastic CEA is designed to account for between-patient sampling variability in cost-effectiveness data assuming that observations are independently distributed. However, between-location variability in cost-effectiveness may result if there is a hierarchical structure in the data; that is, if there is correlation in costs and outcomes between patients recruited in particular locations. This may be expected in multi-location trials given that centres and countries often differ in factors such as clinical practice, patient case-mix and the unit costs of delivering health care. A failure to acknowledge this feature may lead to misleading conclusions in a trial-based economic study. Multilevel modelling (MLM) is an analytical framework that can be used to handle hierarchical cost-effectiveness data. Using data from a recently conducted economic analysis, this paper shows how multilevel modelling can be used to obtain (a) more appropriate estimates of the population average incremental cost-effectiveness and associated standard errors compared to standard stochastic CEA; and (b) location-specific estimates of incremental cost-effectiveness which can be used to explore appropriately the variability between centres/countries of the cost-effectiveness results.
TL;DR: The results suggest that the base effect of disability is overestimated by between 40-60% for men and by 5-10% for women.
Abstract: This paper aims to analyse the effect of disability on participation in the labour force, using the Irish component of the European Community Household Panel Survey 1995-2000. A range of panel models are considered, but to allow for any unobserved influences or state dependence in labour force participation, our preferred model is a dynamic panel model. We show how the estimates of current disability are changed once we control for the effect of past disability and previous participation. We compare base estimates of disability with those controlling for unobserved heterogeneity and past participation. The results suggest that the base effect of disability is overestimated by between 40-60% for men and by 5-10% for women.
TL;DR: This paper found that health has an economically significant effect on employment probabilities for Canadian men and women aged 50-64, and that this effect is underestimated by simple estimates based on self-assessed health.
Abstract: Using longitudinal data from the Canadian National Population Health Survey (NPHS), we study the relationship between health and employment among older Canadians. We focus on two issues: (1) the possible problems with self-reported health, including endogeneity and measurement error, and (2) the relative importance of health changes and long-term health in the decision to work. We contrast estimates of the impact of health on employment using self-assessed health, an objective health index contained in the NPHS - the HUI3, and a 'purged' health stock measure. Our results suggest that health has an economically significant effect on employment probabilities for Canadian men and women aged 50-64, and that this effect is underestimated by simple estimates based on self-assessed health. We also corroborate recent US and UK findings that changes in health are important in the work decision.
TL;DR: This study investigates empirically the design properties of DCEs, in particular, the optimal method of combining alternatives in the choice set, which involves a forced choice between two alternatives with three, four-level, alternative-specific attributes.
Abstract: Experimental design is critical to valid inference from the results of discrete choice experiments (DCEs). In health economics, DCEs have placed limited emphasis on experimental design, typically employing relatively small fractional factorial designs, which allow only strictly linear additive utility functions to be estimated. The extensive literature on optimal experimental design outside health economics has proposed potentially desirable design properties, such as orthogonality, utility balance and level balance. However, there are trade-offs between these properties and emphasis on some properties may increase the random variability in responses, potentially biasing parameter estimates.This study investigates empirically the design properties of DCEs, in particular, the optimal method of combining alternatives in the choice set. The study involves a forced choice between two alternatives (treatment and non-treatment for a hypothetical health care condition), each with three, four-level, alternative-specific attributes. Three experimental design approaches are investigated: a standard six-attribute, orthogonal main effects design; a design that combines alternatives to achieve utility balance, ensuring no alternatives are dominated; and a design that combines alternatives randomly. The different experimental designs did not impact on the underlying parameter estimates, but imposing utility balance increases the random variability of responses.
TL;DR: It is found that medical card eligibility has a consistently positive and significant effect on the utilisation of GP services, however, the differential in visiting rates between medical card patients and others did not narrow between 1987 and 1995 or 2000, as might have been anticipated if supplier-induced demand played a major role prior to the change in reimbursement system.
Abstract: In Ireland, approximately 30% of the population receive free GP services (medical card patients) while the remainder (private patients) must pay for each visit. In 1989, the manner in which GPs were reimbursed by the State for their medical card patients was changed from fee-for-service to capitation while private patients continued to pay on a fee-for-service basis. Concerns about supplier-induced demand were in part responsible for this policy change. The purpose of this paper is to examine the extent to which the utilisation of GP services is influenced by the reimbursement system facing GPs, by comparing visiting rates for the two groups before and after this change. Using a difference-in-differences approach on pooled micro-data from 1987, 1995 and 2000, we find that medical card eligibility has a consistently positive and significant effect on the utilisation of GP services. However, the differential in visiting rates between medical card patients and others did not narrow between 1987 and 1995 or 2000, as might have been anticipated if supplier-induced demand played a major role prior to the change in reimbursement system.