Economic evaluation of health care technologies: A comparison of alternative decision modelling techniques

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University, 14/6/2001.The focus of this thesis is on the application of decision models to the economic evaluation of health care technologies. The primary objective addresses the correct choice of modelling technique, as the attributes of the chosen technique could have a significant impact on the process, as well as the results, of an evaluation. Separate decision models, a Markov process and a discrete event simulation (DES) model are applied to a case study evaluation comparing alternative adjuvant therapies for early breast cancer. The case study models are built and analysed as stochastic models: whereby probability distributions are specified to represent the uncertainty about the true values of the model input parameters. Three secondary objectives are also specified. Firstly, the empirical application of the alternative decision models requires the specification of a 'modelling process' that is not well defined in the health economics literature. Secondly, a comparison of alternative methods for specifying probability distributions to describe the uncertainty in the model's input parameters is undertaken. The final secondary objective covers the application of methods for valuing the collection of additional information to inform the resource allocation decision. The empirical application of the two relevant modelling techniques clarifies the potential advantages derived from the increased flexibility provided by DES over Markov models. The thesis concludes that the use of DES should be strongly considered if either of the following issues appear relevant: model parameters are a function of the time spent in particular states, or the data describing the timing of events are not in the form of transition probabilities. The full description of the modelling process provides a resource for health economists wanting to use decision models. No definitive process is established, however, as there exist competing methods for various stages of the modelling process. The main conclusion from the comparison of methods for specifying probability distributions around the input parameters is that the theoretically specified distributions are most likely to provide a common baseline for comparisons between evaluations. The central question that remains to be addressed is which method is the most theoretically correct? The application of a Vol analysis provides useful insights into the methods employed and leads to the identification of particular methodological issues requiring future research in this area.North Thames training fellowship grant and MRC project gran

Model parameter estimation and uncertainty analysis: a report of the ISPOR-SMDM modeling good research practices task force working group - 6

A model’s purpose is to inform medical decisions and health care resource allocation. Modelers employ quantitative methods to structure the clinical, epidemiological, and economic evidence base and gain qualitative insight to assist decision makers in making better decisions. From a policy perspective, the value of a model-based analysis lies not simply in its ability to generate a precise point estimate for a specific outcome but also in the systematic examination and responsible reporting of uncertainty surrounding this outcome and the ultimate decision being addressed. Different concepts relating to uncertainty in decision modeling are explored. Stochastic (first-order) uncertainty is distinguished from both parameter (second-order) uncertainty and from heterogeneity, with structural uncertainty relating to the model itself forming another level of uncertainty to consider. The article argues that the estimation of point estimates and uncertainty in parameters is part of a single process and explores the link between parameter uncertainty through to decision uncertainty and the relationship to value-of-information analysis. The article also makes extensive recommendations around the reporting of uncertainty, both in terms of deterministic sensitivity analysis techniques and probabilistic methods. Expected value of perfect information is argued to be the most appropriate presentational technique, alongside cost-effectiveness acceptability curves, for representing decision uncertainty from probabilistic analysis

What will make a difference? Assessing the impact of policy and non-policy scenarios on estimations of the future GP workforce

Published online: 28 June 2017Background: Health workforce planning is based on estimates of future needs for and supply of health care services. Given the pipeline time lag for the training of health professionals, inappropriate workforce planning or policies can lead to extended periods of over- or under-supply of health care providers. Often these policy interventions focus on one determinant of supply and do not incorporate other determinants such as changes in population health which impact the need for services. The aim of this study is to examine the effect of the implementation of various workforce policies on the estimated future requirements of the GP workforce, using South Australia as a case study. This is examined in terms of the impact on the workforce gap (excess or shortage), the cost of these workforce policies, and their role in addressing potential non-policy-related future scenarios. Methods: An integrated simulation model for the general practice workforce in South Australia was developed, which determines the supply and level of services required based on the health of the population over a projection period 2013–2033. The published model is used to assess the effects of various policy and workforce scenarios. For each policy scenario, associated costs were estimated and compared to baseline costs with a 5% discount rate applied. Results: The baseline scenario estimated an excess supply of GPs of 236 full-time equivalent (FTE) in 2013 but this surplus decreased to 28 FTE by 2033. The estimates based on single policy scenarios of role substitution and increased training positions continue the surplus, while a scenario that reduces the number of international medical graduates (IMGs) recruited estimated a move from surplus to shortage by 2033. The best-case outcome where the workforce achieves balance by 2023 and remains balanced to 2033, arose when GP participation rates (a non-policy scenario) were combined with the policy levers of increased GP training positions and reduced IMG recruitment. The cost of each policy varied, with increased role substitution and reduced IMG recruitment resulting in savings (AUD$752,946,586 and AUD$3,783,291 respectively) when compared to baseline costs. Increasing GP training costs over the projection period would cost the government an additional AUD$12,719,798. Conclusions: Over the next 20 years, South Australia’s GP workforce is predicted to remain fairly balanced. However, exogenous changes, such as increased demand for GP services may require policy intervention to address associated workforce shortfalls. The workforce model presented in this paper should be updated at regular intervals to inform the need for policy intervention.Caroline O. M. Laurence and Jonathan Karno

What are we paying for? A cost-effectiveness analysis of patented denosumab and generic alendronate for postmenopausal osteoporotic women in Australia

Zoledronic acid and denosumab were funded by the Australian government for the management of osteoporosis at an equivalent price to alendronate. The price of alendronate has declined by around 65 %, but the price of the other two therapies has remained stable. Using data published since the listing, this paper reports current estimates of the value of denosumab compared to alendronate from an Australian health system perspective.A cohort-based state transition model was developed that predicted changes in bone mineral density (BMD), and calibrated fracture probabilities as a function of BMD, age and previous fracture to estimate differences in costs and QALYs gained over a 10-year time horizon.The base-case incremental cost per QALY gained for denosumab versus alendronate was $246,749. There is a near zero probability that denosumab is cost-effective at a threshold value of$100,000 per QALY gained. If the price of denosumab was reduced by 50 %, the incremental cost per QALY gained falls to $50,068.Current Australian legislation precludes price reviews when comparator therapies come off patent. The presented analysis illustrates a review process, incorporating clinical data collected since the original submission to inform a price at which denosumab would provide value for money.Jonathan Karnon, Ainul Shakirah Shafie, Nneka Orji and Sofoora Kawsar Usma

Dynamique des Adventices dans la Culture de Canne À Sucre : Cas de l’Unité Agricole Intégrée de Zuénoula (Centre-Ouest de la Côte d’Ivoire)

L’étude a porté sur la dynamique des adventices de la canne à sucre à l’Unité Agricole intégrée de Zuénoula. Elle avait pour objectif de contribuer à la gestion de l’enherbement dans cette unité agricole. À cet effet, des relevés floristiques ont été réalisés dans 3 classes d’âges de culture de la canne à sucre par la méthode des transects. Ainsi, 133 espèces d’adventices réparties en 36 familles et 92 genres ont été recensées. Les Dicotylédones sont mieux représentées avec 96 contre 37 espèces deMonocotylédones. Dans l’ensemble des classes d’âges, les familles les plus riches en espèces étaient les Poaceae, les Fabaceae, les Euphorbiaceae et les Asteraceae. L’indice de diversité spécifique a montré que le nombre d’espèces adventices augmente avec l’âge de la culture. Ces adventices sont floristiquement homogènes. Certaines espèces telles que Cynodon dactylon, Cyperus rotundus, Dioscorea bulbifera et Ipomoea aquatica ont été plus agressives dans des cultures de 0 à 3 mois. Les plus agressives au niveau des cultures de 4 à 6mois ont été Croton lobatus, Cyperus rotundus, Rottboellia cochinchinensis, Ipomoea involucrata et Momordica charantia. Les parcelles cannières d’au moins 7 mois sont particulièrement agressées par Cynodon dactylon, Ipomoea aquatica, Momordica charantia et Porophyllum ruderale. Les résultats de la présente étude mettent alors en évidence la chronologie d’apparition des adventices dans le cycle cultural de la canne à sucre. Cela devrait permettre la prise de décision optimale pour le désherbage afin d’améliorer la gestion de l’enherbement. This paper focuses on the dynamics of sugarcane weeds at the Integrated Agricultural Unit of Zuénoula. Its purpose was to contribute to the management of grass cover in this agricultural unit. For this purpose, floristic surveys were carried out in three (3) age classes of sugarcane cultivation using the transect method. Thus, 133 species of weeds divided into 36 families and 92 genera were recorded. Dicotyledons are best represented with 96 against 37 species of Monocotyledons. In all age groups, the richest families’ species were Poaceae, Fabaceae, Euphorbiaceae, and Asteraceae. The species diversity index has shown that the number of weed species increases with the age of the crop. These weeds are floristically homogeneous. Some species such as Cynodon dactylon, Cyperus rotundus, Dioscorea bulbifera and Ipomoea aquatica have been more aggressive in 0-3 month old crops. The most aggressive at 4 to 6 month old crops were Croton lobatus, Cyperus rotundus, Rottboellia cochinchinensis, Ipomoea involucrate, and Momordica charantia. The cane plots of at least 7 months are particularly attacked by Cynodon dactylon, Ipomoea aquatica, Momordica charantia and Porophyllum ruderale. The results of this study highlight the chronology of weed occurrence in the sugarcane crop cycle. This should enable optimal decision-making for weed control to improve weed management

Is different better? Models of teaching and their influence on the net financial outcome for general practice teaching posts

Extent: 8p.Background: In Australia, training for general practice (GP) occurs within private practices and their involvement in teaching can have significant financial costs. At the same time there are growing demands for clinical places for all disciplines and for GP there is concern that there are insufficient teaching practices to meet the demand at the medical student, prevocational and vocational training levels. One option to address this may be to change how teaching occurs in the practice. A question that arises in posing such an option is whether different models of teaching change the costs for a teaching practice. The aim of this study is to determine the net financial outcome of teaching models in private GP. Methods: Modelling the financial implications for a range of teaching options using a costing framework developed from a survey of teaching practices in South Australia. Each option was compared with the traditional model of teaching where one GP supervisor is singularly responsible for one learner. The main outcome measure was net financial outcome per week. Decisions on the model cost parameters were made by the study’s Steering Group which comprised of experienced GP supervisors. Four teaching models are presented. Model 1 investigates the gains from teaching multiple same level learners, Models 2 and 3, the benefits of vertically integrated teaching using different permutations, and Model 4 the concept of a GP teacher who undertakes all the teaching. Results: There was a significant increase in net benefits of Aus$547 per week (95$459, $668) to the practice when a GP taught two same level learners (Model 1) and when a senior registrar participated in teaching a prevocational doctor (Model 3, Aus$263, 95% confidence intervals $80,$570). For Model 2, a practice could significantly reduce the loss if a registrar was involved in vertically integrated teaching which included the training of a medical student (Aus$551, 95$419, $718). The GP teacher model resulted in a net remuneration of Aus$207,335 per year, sourced predominantly from the GP teacher activities, with no loss to the practice. Conclusions: Our study costed teaching options that can maximise the financial outcomes from teaching. The inclusion of GP registrars in the teaching model or the supervisor teaching more than one same level learner results in a greater financial benefit. This gain was achieved through a reduction in supervisor teaching time and the sharing of administrative and teaching activities with GP registrars. We also show that a GP teacher who carries a minimal patient load can be a sustainable option for a practice. Further, the costing framework used for the teaching models presented in this study has the ability to be applied to any number of teaching model permutations.Caroline O Laurence, Linda E Black, Carolyn Cheah and Jonathan Karno

It's not the model, it's the way you use it: exploratory early health economics amid complexity; comment on "problems and promises of health technologies: the role of early health economic modelling"

In a review recently published in this journal, Grutters et al outline the scope and impact of their early health economic modelling of healthcare innovations. Their reflections shed light on ways that health economists can shift-away from traditional reimbursement decision-support, towards a broader role of facilitating the exploration of existing care pathways, and the design of options to implement or discontinue healthcare services. This is a crucial role in organisations that face constant pressure to react and adapt with changes to their existing service configurations, but where there may exist significant disagreement and uncertainty on the extent to which change is warranted. Such dynamics are known to create complex implementation environments, where changes risk being poorly implemented or fail to be sustained. In this commentary, we extend the discussion by Grutters et al on early health economic modelling, to the evaluation of complex interventions and systems. We highlight how early health economic modelling can contribute to a participatory approach for ongoing learning and development within healthcare organisations.Andrew Partington, Jonathan Karno

In-DEPtH framework: evidence-in formed, co-creation framework for the Design, Evaluation and Procurement of Health services

With a multitude of variables, the combinations of care, health program activities and outcomes are infinite, and this renders improvement efforts to complex health service interventions particularly intricate. Here, we describe a framework that seeks to incorporate research evidence and the multi-faceted considerations of stakeholders, context and resources to co-create sustainable health solutions that improve the health outcomes of patients and communities. This evidence-informed, co-creation framework for the Design, Evaluation and Procurement of Health services (in-DEPtH) is a systematic approach to support health agencies to commission services that are evidence-informed, contextually relevant and stakeholder engaged. The framework consists of several steps from defining the research question, health outcomes and search inclusion criteria, to the synthesis of evidence, and to co-creation and Delphi consultations with stakeholders. In this paper, we describe the various steps of the framework and explain the theoretical methods underpinning the framework. The approach of the framework is context neutral and can be applied to healthcare systems of different countries.Kenneth Lo, Jonathan Karno