Multi-GeV Electron Acceleration in Wakefields Strongly Driven by Oversized Laser Spots.

Experiments were performed on laser wakefield acceleration in the highly nonlinear regime. With laser powers P<250 TW and using an initial spot size larger than the matched spot size for guiding, we were able to accelerate electrons to energies E_{max}>2.5 GeV, in fields exceeding 500 GV m^{-1}, with more than 80 pC of charge at energies E>1 GeV. Three-dimensional particle-in-cell simulations show that using an oversized spot delays injection, avoiding beam loss as the wakefield undergoes length oscillation. This enables injected electrons to remain in the regions of highest accelerating fields and leads to a doubling of energy gain as compared to results from using half the focal length with the same laser.

Rehabilitation for people wearing offloading devices for diabetes-related foot ulcers: a systematic review and meta-analyses.

BACKGROUND: Offloading devices improve healing of diabetes-related foot ulcers (DFUs) but they can limit mobilisation. Rehabilitation during or after removal of these devices may promote physical activity in a population at risk of poor health outcomes for which inactivity is a reversible risk factor. METHODS: This systematic review examined the effectiveness of rehabilitation interventions to promote physical activity during and/or after wearing an offloading device to treat diabetes-related foot ulcers. Searches using MESH terms and free-text combinations: 'foot ulcer', 'diabetic foot', 'casts, surgical', 'orthotic devices' were applied to MEDLINE, Embase, The Cochrane Library and clinical trial registers for randomised and observational studies published to September 2022. Methodological quality assessment of included studies was undertaken using the Cochrane Risk of Bias (RoB 2.0) and Risk of Bias In Non-randomised studies of Interventions (ROBINS-I) tools. RESULTS: Of 3332 records identified, eight studies (441 participants), four clinical trials and four cohort studies, were included. None delivered or tested a structured rehabilitation programme, but all reported physical activity outcomes during or after device use. People wearing non-removable total contact casts were less active than those wearing devices (SMD -0.45; 95% CI - 0.87 to - 0.04; p = 0.03; I2 56%; 4 trials). Diabetes-related foot ulcers in people wearing total contact casts were more likely to heal compared to removable devices at 12 weeks (OR 2.69; 95% CI 0.97 to 7.45; p = 0.06; I2 = 64%; 4 trials) and 20 weeks (OR 2.35; 95% CI 0.95 to 5.82; p = 0.07; I2 = 65%; 4 trials). CONCLUSIONS: Despite physical activity being low throughout off-loading treatment, no studies have specifically tested rehabilitation. There is a need to investigate the clinical and cost-effectiveness of rehabilitation programmes in this population. High quality trials are needed to provide robust evidence to support to rehabilitation after DFU treatment.

Automation and control of laser wakefield accelerators using Bayesian optimization.

Laser wakefield accelerators promise to revolutionize many areas of accelerator science. However, one of the greatest challenges to their widespread adoption is the difficulty in control and optimization of the accelerator outputs due to coupling between input parameters and the dynamic evolution of the accelerating structure. Here, we use machine learning techniques to automate a 100 MeV-scale accelerator, which optimized its outputs by simultaneously varying up to six parameters including the spectral and spatial phase of the laser and the plasma density and length. Most notably, the model built by the algorithm enabled optimization of the laser evolution that might otherwise have been missed in single-variable scans. Subtle tuning of the laser pulse shape caused an 80% increase in electron beam charge, despite the pulse length changing by just 1%.

Capturing accelerometer outputs in healthy volunteers under normal and simulated-pathological conditions using ML classifiers.

Wearable devices offer a possible solution for acquiring objective measurements of physical activity. Most current algorithms are derived using data from healthy volunteers. It is unclear whether such algorithms are suitable in specific clinical scenarios, such as when an individual has altered gait. We hypothesized that algorithms trained on healthy population will result in less accurate results when tested in individuals with altered gait. We further hypothesized that algorithms trained on simulated-pathological gait would prove better at classifying abnormal activity. We studied healthy volunteers to assess whether activity classification accuracy differed for those with healthy and simulated-pathological conditions. Healthy participants (n=30) were recruited from the University of Leeds to perform nine predefined activities under healthy and simulated-pathological conditions. Activities were captured using a wrist-worn MOX accelerometer (Maastricht Instruments, NL). Data were analyzed based on the Activity-Recognition-Chain process. We trained a Neural-Network, Random-Forests, k-Nearest-Neighbors (k-NN), Support-Vector-Machines (SVM) and Naive Bayes models to classify activity. Algorithms were trained four times; once with `healthy' data, and once with `simulated-pathological data' for each of activity-type and activity-task classification. In activity-type instances, the SVM provided the best results; the accuracy was 98.4% when the algorithm was trained and then tested with unseen data from the same group of healthy individuals. Accuracy dropped to 52.8% when tested on simulated-pathological data. When the model was retrained with simulated-pathological data, prediction accuracy for the corresponding test set was 96.7%. Algorithms developed on healthy data are less accurate for pathological conditions. When evaluating pathological conditions, classifier algorithms developed using data from a target sub-population can restore accuracy to above 95%.

Prognosis of the infected diabetic foot ulcer: a 12-month prospective observational study.

AIMS: To determine clinical outcomes and explore prognostic factors related to ulcer healing in people with a clinically infected diabetic foot ulcer. METHODS: This multicentre, prospective, observational study reviewed participants' data at 12 months after culture of a diabetic foot ulcer requiring antibiotic therapy. From participants' notes, we obtained information on the incidence of wound healing, ulcer recurrence, lower extremity amputation, lower extremity revascularization and death. We estimated the cumulative incidence of healing at 6 and 12 months, adjusted for lower extremity amputation and death using a competing risk analysis, and explored the relationship between baseline factors and healing incidence. RESULTS: In the first year after culture of the index ulcer, 45/299 participants (15.1%) had died. The ulcer had healed in 136 participants (45.5%), but recurred in 13 (9.6%). An ipsilateral lower extremity amputation was recorded in 52 (17.4%) and revascularization surgery in 18 participants (6.0%). Participants with an ulcer present for ~2 months or more had a lower incidence of healing (hazard ratio 0.55, 95% CI 0.39 to 0.77), as did those with a PEDIS (perfusion, extent, depth, infection, sensation) perfusion grade of ≥2 (hazard ratio 0.37, 95% CI 0.25 to 0.55). Participants with a single ulcer on their index foot had a higher incidence of healing than those with multiple ulcers (hazard ratio 1.90, 95% CI 1.18 to 3.06). CONCLUSIONS: Clinical outcomes at 12 months for people with an infected diabetic foot ulcer are generally poor. Our data confirm the adverse prognostic effect of limb ischaemia, longer ulcer duration and the presence of multiple ulcers.

An investment appraisal approach to clinical trial design.

In this paper, a general investment appraisal model is presented which shows how pharmaceutical companies could take profit considerations into account when making decisions about the design of randomized controlled trials. A general model is presented based on the net present value method of investment appraisal. The approach is illustrated with a hypothetical example which shows how optimal (net present value maximizing) designs can be determined based on choices about sample size and endpoint measurement. The method could be extended to accommodate considerations about other trial design features, and could be used to determine a portfolio of studies which maximizes the expected return on a given development or trial budget. Furthermore, the approach could be used by pharmaceutical companies to evaluate the incremental costs and benefits of incorporating non-clinical objectives into trials, such as quality of life research and economic evaluation studies. A number of practical difficulties would need to be overcome to utilize the approach. Directions for further research are therefore highlighted centred on the key components of the model: a trial cost function, a product demand function, innovation diffusion processes and Bayesian approaches to trial design.

Choice of NSAID and management strategy in rheumatoid arthritis and osteoarthritis. The impact on costs and outcomes in the UK.

OBJECTIVE: Although nonsteroidal anti-inflammatory drugs (NSAIDs) are an effective therapy for rheumatoid arthritis, they are associated with significant adverse effects, the management of which imposes additional costs on the healthcare system. Prescribing NSAIDs which have a lower risk of major adverse effects as the first-line NSAID for patients with rheumatoid arthritis and osteoarthritis may be expected to lead to an improvement in clinical outcomes and reduce overall treatment costs. This analysis examines data from a published randomised controlled trial of 5 NSAIDs to explore these hypotheses. DESIGN AND SETTING: Data from a clinical trial comparing 5 NSAIDs were combined with published cost data to construct 2 clinical decision models, reflecting alternative approaches to the management of major and minor adverse effects in the UK. INTERVENTIONS: The 5 NSAIDs evaluated in the analysis were nabumetone, diclofenac, ibuprofen, piroxicam and naproxen, although only the results for ibuprofen and nabumetone are reported. MAIN OUTCOME MEASURES AND RESULTS: The total cost of care per patient receiving nabumetone was estimated to be between 25 pounds sterling (Pound) and 41 Pounds more expensive than ibuprofen. In a hypothetical cohort of 100,000 patients, there were between 690 and 821 more major adverse effects using ibuprofen than nabumetone. The cost per life-year gained (LYG) from using nabumetone rather than ibuprofen ranged between 1880 Pounds and 2517 Pounds (1995 values), depending upon the management of adverse effects. CONCLUSIONS: These results indicate that: (i) prescribing the newer, currently more expensive, NSAIDs will not necessarily lead to cost savings; (ii) the management of adverse effects can have a significant impact on costs; and (iii) the additional cost may be justifiable in terms of the mortality and morbidity gains associated with the new lower-risk NSAIDs.

Economic evaluation of antiviral therapy for the treatment of herpes zoster in immunocompetent adults.

Shingles (herpes zoster) affects 20% of the population at some stage during their lives. The economic consequences can be significant. For example, in the UK, the costs of post-herpetic neuralgia, a complication that affects between 10 and 14% of patients with shingles, have been estimated between 4.8 million and 17.9 million pounds sterling (Pounds). This study is the first formal assessment of the cost-effectiveness of the 2 most commonly used oral antiviral treatments that have proven efficacy in patients with shingles: famciclovir and aciclovir (acyclovir). It shows that the clinical advantages of famciclovir over aciclovir are accompanied by potential economic advantages in the form of savings in direct costs to the UK National Health Service of between 2.04 pounds and 16.85 pounds per patient treated. Future economic research to validate the benefits of antiviral treatment should focus on prospective assessments alongside controlled trials incorporating resource use analysis, quality-of-life appraisal, assessments of pain severity, and long term follow-up with continuation protocols.

Results of the economic evaluation of the first study. A multinational prospective economic evaluation. FIRST Investigators. Flolan International Randomized Survival Trial.

We present the prospective economic evaluation that served as a secondary endpoint for the FIRST study, a randomized international multicenter trial of patients with severe congestive heart failure. Although the clinical results of this study were disappointing, we demonstrated the feasibility of incorporating prospective economic evaluation in phase III clinical trials.

The economic evaluation of the FIRST study: design of a prospective analysis alongside a multinational phase III clinical trial. Flolan International Randomized Survival Trial.

Prospective economic assessments of new pharmaceutical therapies are increasingly being incorporated into phase III clinical trials. We report on the design of an economic evaluation integrated into the Flolan International Randomized Survival Trial (FIRST). Economic evaluation was considered a critical component of the assessment of this therapy given the resources required to administer epoprostenol (Flolan), a therapy that would require lifelong continuous intravenous infusion. Economic secondary endpoints were incorporated in the clinical trial. The economic evaluation of the treatment was integrated into all aspects of study development, including study design, implementation, and monitoring. Since this was a multinational trial, special care was required to ensure that the protocol design was appropriate for all study countries. The economic assessment required the development of several methodologic components: a set of background economic concepts to guide protocol development, a set of resource items to be recorded when required for study participants; a set of data collection instruments for assessment of health-related quality of life for study patients; and a protocol for a resource costing exercise for the study. We report the data elements included in the study design, as well as a discussion of some of the issues faced in developing the economic evaluation for this trial.

The analysis of censored treatment cost data in economic evaluation.

This article investigates the way in which the presence of censored cost data in clinical trials should dictate the inferential tests adopted when comparing treatment and nontreatment groups for the purpose of economic evaluation. The authors argue that the techniques of survival analysis are appropriate where censoring is present, and that bias will be imparted if cruder methods are used to analyze cost data, even if that data is drawn from a relevant population. The first section of the article discusses the problem of censoring and survival analysis, while the second examines three methods of dealing with censored cost data and possible biases resulting from them. The third section presents results from actual trial data using the three methods described in the preceding section. Conclusions are presented in section four, where it is argued that these methodological issues are likely to become more important as economists are called upon to evaluate the treatment of chronic conditions using data from clinical trials with finite end points.

Synthetic surfactant for rescue treatment of respiratory distress syndrome in premature infants weighing from 700 to 1350 grams: impact on hospital resource use and charges.

To determine the impact of the use of synthetic surfactant on hospital resource use and charges, we analyzed the economic data from a multicenter, randomized, placebo-controlled clinical trial of synthetic surfactant in infants with neonatal respiratory distress syndrome and birth weights between 700 and 1350 gm. Two 5 ml/kg doses of a synthetic surfactant (Exosurf Neonatal) or air placebo were administered to 419 infants who were receiving mechanical ventilation and had an arterial/alveolar oxygen tension ratio < 0.22. In addition to the clinical endpoints for safety and efficacy, data were collected on length of hospital stay, days in the neonatal intensive care unit, days of mechanical ventilation, days of oxygen supplementation, and hospital charges until the infant reached 1 year adjusted age. Growth and development of infants who received synthetic surfactant therapy in the study and survived to 1 year adjusted age were equivalent to those of the survivors in the air placebo group. For 1-year survivors, synthetic surfactant reduced the average length of stay at the different levels of care needed during the hospitalization such as neonatal intensive care unit days, days of mechanical ventilation, and days of oxygen supplementation. For nonsurvivors, synthetic surfactant increased the average length of stay, especially at more intense levels of care. Total hospital charges for the initial hospitalization and through 1 year adjusted age for a hypothetic cohort of 100 infants treated with synthetic surfactant were, on average, the same as those for a comparable cohort of infants in the air placebo group. These results indicate that rescue therapy with synthetic surfactant in infants with respiratory distress syndrome and birth weights from 700 to 1350 gm can result in significantly improved survival without significant increases in hospital charges.

Economic outcomes of colfosceril palmitate rescue therapy in infants weighing 1250g or more with respiratory distress syndrome: results from a randomised trial.

An analysis of the economic data from a multicentre, randomised, placebo-controlled clinical trial of colfosceril palmitate in infants with neonatal respiratory distress syndrome (NRDS) and birthweights of 1250g or more is presented. Two 5 ml/kg (67.5 mg/kg) doses of a synthetic surfactant (colfosceril palmitate) or air placebo were administered to 1237 infants who were receiving mechanical ventilation and had an arterial/alveolar oxygen tension ratio of less than 0.22. In addition to the clinical end-points for safety and efficacy, data were collected on length of hospital stay, days in the neonatal intensive care unit, days on mechanical ventilation, days on oxygen, and hospital charges until the child reached 1-year adjusted age. One-year adjusted age is attained when the time elapsed since birth is equal to 365 days plus the number of days of prematurity. Rescue treatment with synthetic surfactant therapy has been shown to reduce the incidence of complications of NRDS. Growth and development of infants who received colfosceril palmitate therapy in the study and survived to 1-year adjusted age were equivalent to those of the survivors in the air placebo group. For the cohort of treated infants, colfosceril palmitate reduced the average length of stay at 2 levels of care needed during both the initial hospitalisation (a reduction of 8 days overall and 5 days in intensive care) and all first year hospitalisations (a reduction of 9 days overall and 5 days in intensive care). Total hospital charges for the initial hospitalisation and through 1-year adjusted age for a hypothetical cohort of 100 infants treated with colfosceril palmitate were less than those for a comparable cohort in the air placebo group. The results would, therefore, suggest that rescue therapy with colfosceril palmitate in infants with NRDS and birthweights over 1250g can result in substantial reductions in hospital resource utilisation and charges in addition to the clinical benefits associated with its use.

Assessing the economic benefits of antiherpes therapy.

Increasing pressures on health-care budgets mean that health-care treatments and programmes need not only to demonstrate that they are efficacious, but also that they deliver good value for money. In the context of pharmaceuticals it is likely that both in Australia and Ontario (Canada) evidence of cost effectiveness will become a mandatory requirement prior to reimbursement (government subsidy) of drugs. However, in most jurisdictions economic data will be one of a number of factors taken into account by decision makers, be they policy makers, members of formulary committees, or individual prescribers. Methods of economic evaluation have been developed for the assessment of healthcare treatments, but these have not been extensively applied to antiherpes therapy. However, this paper, based on a literature review of the clinical trials of acyclovir, shows that there are many indicators of potential economic benefit, depending on the clinical indication, in length or quality of life, savings in other health-care resources, or wider benefits (e.g., reductions in lost work time). If appropriate economic data are to be gathered in future for new antiherpes therapy, a more systematic approach is required, conducting economic evaluation alongside, or as an integral part of, clinical trials. This raises important logistical and methodological challenges. It is important that researchers acknowledge these challenges early so that they can be adequately addressed.

International cross-section analysis of the determination of mortality.

An essential ingredient in the evaluation of policies concerning health services is knowledge of the impact of health services and other factors on the health of the population. One method of obtaining this information is from the regression analysis of international cross-section data on mortality rates, health service provision, income levels, consumption patterns, and other variables hypothesised to affect population health. The investigation of the determinants of population health is in many ways akin to the estimation of production functions which describe the relationship between the output of goods or services and the mix of inputs used in their production. The purpose of our paper is to use this analogy to discuss, and provide examples of, the problems which arise with the statistical investigation of mortality rates. Issues raised include simultaneous equation bias, multicollinearity, selection of explanatory variables, omitted variable bias, definition and measurement of variables, functional forms, lagged relationships and temporal stability. These problems are illustrated by replication and re-analysis, using new data, of the well known study by Cochrane, St Leger and Moore.