Cost-effectiveness analysis of imaging surveillance in stage II and III extremity soft tissue sarcoma: an Australian perspective.

BACKGROUND: Surveillance imaging is used to detect local and/or distant recurrence following primary treatment of localised soft tissue sarcoma (STS), however evidence supporting optimal surveillance modality or frequency is lacking. We used prospectively collected sarcoma data to describe current surveillance imaging practice in patients with AJCC stage II and III extremity STS and evaluate its cost-effectiveness. METHODS: From three selected Australian sarcoma referral centres, we identified patients with stage II and III extremity STS treated between 2009 and 2013. Medical records were reviewed to ascertain surveillance imaging practices, including modality, frequency and patient outcomes. A discrete event simulation model was developed and calibrated using clinical data to estimate health service costs and quality adjusted life years (QALYs) associated with alternative surveillance strategies. RESULTS: Of 133 patients treated for stage II and III extremity STS, the majority were followed up with CT chest (86%), most commonly at 3-monthly intervals and 62% of patients had the primary site imaged with MRI at 6-monthly. There was limited use of chest-X-ray. A discrete event simulation model demonstrated that CT chest screening was the most cost effective surveillance strategy, gaining additional QALYs at a mean incremental cost of $30,743. MRI alone and PET-CT alone were not cost-effective, whilst a combined strategy of CT + MRI had an incremental cost per QALY gained of $96,556. CONCLUSIONS: Wide variations were observed in surveillance imaging practices in this high-risk STS cohort. Modelling demonstrated the value of CT chest for distant recurrence surveillance over other forms of imaging in terms of cost and QALYs. Further work is required to evaluate cost-effectiveness in a prospective manner.

Systematic review of reducing population meat consumption to reduce greenhouse gas emissions and obtain health benefits: effectiveness and models assessments.

OBJECTIVES: This review evaluates existing co-benefit models for emission and health outcomes of counterfactual scenarios of reduced meat consumption at a population level. METHODS: A novel assessment process was developed, combining selected measures from the Cochrane Review quality assessment tools, from the PRISMA checklist, and model quality measures identified by the authors during the preliminary phases of the review process. RESULTS: Four emission models and three health outcome models have been identified which show great variation in model characteristics and qualities. The estimated counterfactual scenario emission effects presented in the included studies ranged from a reduction of <3-30 % and reduction in the burden of disease ranged from 1 to 16 %. Meta-analysis could not be conducted due to high heterogeneity of model characteristics. CONCLUSIONS: All co-benefit studies estimated that reducing population meat consumption could reduce greenhouse gas emissions and the burden of disease. However, important attention must be paid to nutrition balance and a systematic approach in input and output attribute parameters is recommended for better model quality.

Accounting for costs, QALYs, and capacity constraints: using discrete-event simulation to evaluate alternative service delivery and organizational scenarios for hospital-based glaucoma services.

BACKGROUND: Decision-analytic models are routinely used as a framework for cost-effectiveness analyses of health care services and technologies; however, these models mostly ignore resource constraints. In this study, we use a discrete-event simulation model to inform a cost-effectiveness analysis of alternative options for the organization and delivery of clinical services in the ophthalmology department of a public hospital. The model is novel, given that it represents both disease outcomes and resource constraints in a routine clinical setting. METHODS: A 5-year discrete-event simulation model representing glaucoma patient services at the Royal Adelaide Hospital (RAH) was implemented and calibrated to patient-level data. The data were sourced from routinely collected waiting and appointment lists, patient record data, and the published literature. Patient-level costs and quality-adjusted life years were estimated for a range of alternative scenarios, including combinations of alternate follow-up times, booking cycles, and treatment pathways. RESULTS: The model shows that a) extending booking cycle length from 4 to 6 months, b) extending follow-up visit times by 2 to 3 months, and c) using laser in preference to medication are more cost-effective than current practice at the RAH eye clinic. CONCLUSIONS: The current simulation model provides a useful tool for informing improvements in the organization and delivery of glaucoma services at a local level (e.g., within a hospital), on the basis of expected effects on costs and health outcomes while accounting for current capacity constraints. Our model may be adapted to represent glaucoma services at other hospitals, whereas the general modeling approach could be applied to many other clinical service areas.

Contribution of active membrane processes to conducted hyperpolarization in arterioles of hamster cheek pouch.

OBJECTIVE: Conduction of vasodilation triggered by acetylcholine (ACh) in arteriolar networks reflects hyperpolarization and its spread from cell to cell along the vessel wall. The amplitude and distance of the vasomotor response appear greater than can be explained by simple passive decay of the electrical signal. The authors tested the hypothesis that the conduction of hyperpolarization involves active membrane processes as the signal travels along the arteriolar wall. METHODS: Intracellular recordings of membrane potential were made from either the smooth muscle or endothelial cell layer of arterioles of the hamster cheek pouch in vivo. Acetylcholine was delivered onto an arteriole using microiontophoresis at defined distances from the recording site, and transient hyperpolarizations were recorded. The area enclosed by the transients (voltage x time integral below baseline) was measured and compared to the area expected if the hyperpolarization was spreading passively. RESULTS: In 11 of 15 recordings from smooth muscle and 5 of 7 from endothelium, areas of the transients were larger than expected for purely passive spread of the electrical signal. CONCLUSIONS: Conduction of hyperpolarization is enhanced by active membrane processes as the signal travels along the arteriolar wall. Signal augmentation will promote blood flow to tissue regions from which hyperpolarization of arterioles originates.