ORCID Profile
0000-0003-3746-9913
Current Organisation
University of York
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Publisher: SAGE Publications
Date: 09-2012
Abstract: 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.
Publisher: Elsevier BV
Date: 09-2012
DOI: 10.1016/J.JVAL.2012.04.014
Abstract: 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, in terms of both 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.
Publisher: American Society of Clinical Oncology (ASCO)
Date: 20-08-2016
Publisher: Oxford University Press (OUP)
Date: 30-03-2016
Publisher: Massachusetts Medical Society
Date: 29-12-2011
Publisher: National Institute for Health and Care Research
Date: 09-2008
DOI: 10.3310/HTA12310
Abstract: To evaluate the clinical effectiveness, cost-effectiveness and safety of a policy of relatively early laparoscopic surgery compared with continued medical management amongst people with gastro-oesophageal reflux disease (GORD) judged suitable for both policies. Relative clinical effectiveness was assessed by a randomised trial (with parallel non-randomised preference groups) comparing a laparoscopic surgery-based policy with a continued medical management policy. The economic evaluation compared the cost-effectiveness of the two management policies in order to identify the most efficient provision of future care and describe the resource impact that various policies for fundoplication would have on the NHS. A total of 21 hospitals throughout the UK with a local partnership between surgeon(s) and gastroenterologist(s) who shared the secondary care of patients with GORD. The 810 participants, who were identified retrospectively or prospectively via their participating clinicians, had both documented evidence of GORD (endoscopy and/or manometry/24-hour pH monitoring) and symptoms for longer than 12 months. In addition, the recruiting clinician(s) was clinically uncertain about which management policy was best. Of the 810 eligible patients who consented to participate, 357 were recruited to the randomised arm of the trial (178 allocated to surgical management, 179 allocated to continued, but optimised, medical management) and 453 recruited to the parallel non-randomised preference arm (261 chose surgical management, 192 chose to continue with best medical management). The type of fundoplication was left to the discretion of the surgeon. Participants completed a baseline REFLUX questionnaire, developed specifically for this study, containing a disease-specific outcome measure, the Short Form with 36 Items (SF-36), the EuroQol-5 Dimensions (EQ-5D) and the Beliefs about Medicines and Surgery questionnaires (BMQ/BSQ). Postal questionnaires were completed at participant-specific time intervals after joining the trial (equivalent to approximately 3 and 12 months after surgery). Intraoperative data were recorded by the surgeons and all other in-hospital data were collected by the research nurse. At the end of the study period, participants completed a discrete choice experiment questionnaire. The randomised groups were well balanced at entry. Participants had been taking GORD medication for a median of 32 months the mean age of participants was 46 years and 66% were men. Of 178 randomised to surgery, 111 (62%) actually had fundoplication. There was a mixture of clinical and personal reasons why some patients did not have surgery, sometimes related to long waiting times. A total or partial wrap procedure was performed depending on surgeon preference. Complications were uncommon and there were no deaths associated with surgery. By the equivalent of 12 months after surgery, 38% in the randomised surgical group (14% amongst those who had surgery) were taking reflux medication compared with 90% in the randomised medical group. There were substantial differences (one-third to one-half standard deviation) favouring the randomised surgical group across the health status measures, the size depending on assumptions about the proportion that actually had fundoplication. These differences were the same or somewhat smaller than differences observed at 3 months. The lower the REFLUX score, the worse the symptoms at trial entry and the larger the benefit observed after surgery. The preference surgical group had the lowest REFLUX scores at baseline. These scores improved substantially after surgery, and by 12 months they were better than those in the preference medical group. The BMQ/BSQ and discrete choice experiment did distinguish the preference groups from each other and from the randomised groups. The latter indicated that the risk of serious complications was the most important single attribute of a treatment option. A within-trial cost-effectiveness analysis suggested that the surgery policy was more costly (mean 2049 pounds) but also more effective [+0.088 quality-adjusted life-years (QALYs)]. The estimated incremental cost per QALY was 19,000-23,000 pounds, with a probability between 46% (when 62% received surgery) and 19% (when all received surgery) of cost-effectiveness at a threshold of 20,000 pounds per QALY. Modelling plausible longer-term scenarios (such as lifetime benefit after surgery) indicated a greater likelihood (74%) of cost-effectiveness at a threshold of 20,000 pounds, but applying a range of alternative scenarios indicated wide uncertainty. The expected value of perfect information was greatest for longer-term quality of life and proportions of surgical patients requiring medication. Amongst patients requiring long-term medication to control symptoms of GORD, surgical management significantly increases general and reflux-specific health-related quality of life measures, at least up to 12 months after surgery. Complications of surgery were rare. A surgical policy is, however, more costly than continued medical management. At a threshold of 20,000 pounds per QALY it may well be cost-effective, especially when putative longer-term benefits are taken into account, but this is uncertain. The more troublesome the symptoms, the greater the potential benefit from surgery. Uncertainty about cost-effectiveness would be greatly reduced by more reliable information about relative longer-term costs and benefits of surgical and medical policies. This could be through extended follow-up of the REFLUX trial cohorts or of other cohorts of fundoplication patients. Current Controlled Trials ISRCTN15517081.
Publisher: Springer Science and Business Media LLC
Date: 07-2000
DOI: 10.2165/00019053-200018010-00002
Abstract: In the absence of interventions, 20% of infants born to women infected with HIV acquire infection from their mother at or before delivery. A further 15% are infected through breast feeding. Prenatal testing for HIV allows infected women to be reliably identified so that they can receive antiretroviral therapy and, in countries with safe water supplies, be advised not to breast feed. These and other interventions can reduce the risk of transmission to 5% or less. Economic evaluations of prenatal testing for HIV are reviewed and compared in this article, and future research priorities outlined. These studies set the costs of testing and intervention against the averted lifetime costs of paediatric infection, and generate estimates of the HIV prevalence threshold above which there would be a net cost saving, or calculate the cost per life-year saved given a particular prevalence. In the developed world, prenatal testing has been adopted in many countries, and recent economic analyses broadly support this. Future research is likely to focus on the incremental benefits of different antiretroviral regimens in lowering transmission rates still further, with or without elective caesarean section, and the possibility that some may lead to adverse effects in uninfected infants exposed to them in utero. Some earlier assessments in resource-poor settings concluded that prenatal testing was unaffordable or of doubtful cost effectiveness. This negative conclusion appears to be the result of very low estimates of the lifetime costs of paediatric HIV infection, together with developed world conceptions of pre-test counselling. The demonstration that nevirapine reduces transmission risk at a low cost has transformed the outlook, and there is hope that antiretrovirals can act prophylactically to prevent infection of the breast-fed child. However, to achieve a sustained reduction in vertical transmission there may be a need to evaluate the need for a strengthened infrastructure to deliver prenatal HIV testing and treatment, as well as programmes to reduce HIV incidence in adults.
Publisher: BMJ
Date: 14-07-2009
DOI: 10.1136/BMJ.B2576
Publisher: National Institute for Health and Care Research
Date: 06-2013
DOI: 10.3310/HTA17220
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 07-1998
DOI: 10.1097/00002030-199811000-00021
Abstract: To estimate the cost-effectiveness of alternative interventions to reduce the risk of mother-to-child transmission of HIV. A model capturing the sequential nature of mother-to-child transmission in utero, at delivery and postnatally was used to determine how the effects of bottle-feeding, elective Cesarean section (CS) and zidovudine (ZDV) would combine to prevent mother-to-child HIV transmission. Parameter estimates were derived from the literature, UK health service costs applied, and incremental cost effectiveness ratios (ICER) estimated for alternative risk reduction strategies. Results can be transposed to other cost assumptions or currencies. In a woman who breast-feeds her baby, has a vaginal or emergency CS delivery and takes no ZDV, the estimated transmission risk is 31.6% (range, 23.7-38.1%), at a cost of 400 UK pound per woman this falls to a risk of 3.7% (range, 1.7-6.9%) when bottle-feeding, ZDV therapy and elective CS are all implemented at a cost of 1968 UK pound per woman. From a public health perspective the ICER of ZDV and elective CS each depend on the acceptance rates of the other. In women counselled against breast-feeding, ZDV with 100% acceptance of elective CS has an ICER of 11 342 UK pound (95% confidence interval (CI), 7084-21 515 UK pound]. However, the ICER of CS ranges from 9248 UK pound (95% CI, 5072-46 913 pound sterling) at zero ZDV acceptance to 27 895 UK pound (95% CI, 10 018-154 462 pound sterling) at 100% ZDV acceptance. Considering the estimated cost of caring for an infected child, ZDV appears to be cost-effective under any of the circumstances examined. However, elective CS may not be cost-effective in populations where the uptake of ZDV is high, and a more precise estimate of its efficacy is required.
Publisher: Cambridge University Press (CUP)
Date: 27-09-2023
Publisher: BMJ
Date: 15-12-2008
DOI: 10.1136/BMJ.A2664
Publisher: Elsevier BV
Date: 08-2015
Publisher: Springer Science and Business Media LLC
Date: 10-12-2015
Publisher: Public Library of Science (PLoS)
Date: 24-09-2013
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Mark Sculpher.