Feasibility of the physiological cost index as an outcome measure for the assessment of energy expenditure during walking

Objective: To determine if the Physiological Cost Index (PCI) can be recommended as an outcome measure in clinical trials. Design: Three assessments were performed, 2 with shoes, 1 without. The difference between walking with shoes and walking barefoot was used to study the ability of the PCI to detect a change in the criterion standard. Setting: A research department affiliated with a rehabilitation hospital in the Netherlands. Participants: Twelve children with cerebral palsy. Interventions: During the first and third assessments, the children walked with shoes. During the intermediate assessment, the children walked without shoes. Main Outcome Measures: Breath-by-breath oxygen uptake, heart rate (HR), and walking speed were measured at a self-selected comfortable speed. Oxygen cost (EO2) and the PCI were subsequently calculated offline. Feasibility judgments were made regarding the ability of the PCI to detect changes in a criterion standard and the statistical power of the outcome measure. Results: Pearson correlation coefficients were .66 and .62 for HRwalking-HRbaseline and HRwalking, respectively. The smallest detectable difference of the PCI and EO2 were 69% and 32%, respectively. A difference of at least 69% or 32% should be found before one can conclude a difference with a certainty of 95%. Conclusions: The reproducibility of the PCI and the ability to show small differences in EO2 were moderate. Subtracting HRbaseline when calculating the PCI is probably not useful because it only increased within-subject variability. With respect to statistical power of a new clinical trial, we recommend using EO2 instead of the PCI

Netwerk in beweging... door technologische innovaties in de neurorevalidatie

Er zijn vele neurologische aandoeningen bekend, maar ik zal me vandaag beperken tot een tweetal voor de revalidatie belangrijke, de hersenbloeding (of herseninfarct) en de dwarslaesie. Dit zijn beide centraal neurologische aan- doeningen, hetgeen betekent dat het aandoeningen zijn van het centrale zenuwstelsel (de hersenen of ruggenmerg)

Assessment of the added value of the Twente Photoacoustic Mammoscope in breast cancer diagnosis\ud

Purpose: Photoacoustic (PA) imaging is a recently developed breast cancer imaging technique. In order to enhance successful clinical implementation, we quantified the potential clinical value of different scenarios incorporating PA imaging by means of multi-criteria analysis. From this analysis, the most promising area of application for PA imaging in breast cancer diagnosis is determined, and recommendations are provided to optimize the design of PA imaging. - \ud Methods: The added value of PA imaging was assessed in two areas of application in the diagnostic track. These areas include PA imaging as an alternative to x-ray mammography and ultrasonography in early stage diagnosis, and PA imaging as an alternative to Magnetic Resonance Imaging (MRI) in later stage diagnosis. The added value of PA imaging was assessed with respect to four main criteria (costs, diagnostic performance, patient comfort and risks). An expert panel composed of medical, technical and management experts was asked to assess the relative importance of the criteria in comparing the alternative diagnostic devices. The judgments of the experts were quantified based on the validated pairwise comparison technique of the Analytic Hierarchy Process, a technique for multi-criteria analysis. Sensitivity analysis was applied to account for the uncertainty of the outcomes. - \ud Results: Among the considered alternatives, PA imaging is the preferred technique due to its non-invasiveness, low cost and low risks. However, the experts do not expect large differences in diagnostic performance. The outcomes suggest that design changes to improve the diagnostic performance of PA imaging should focus on the quality of the reconstruction algorithm, detector sensitivity, detector bandwidth and the number of wavelengths used. - \ud Conclusion: The AHP method was useful in recommending the most promising area of application in the diagnostic track for which PA imaging can be implemented, this being early diagnosis, as a substitute for the combined use of x-ray mammography and ultrasonography

Modeling of Whole Genomic Sequencing Implementation using System Dynamics and Game Theory

Biomarker testing is a laboratory test in oncology that is used in the selection of targeted cancer treatments and helping to avoid ineffective treatments. There exist several types of biomarker tests that can be used to detect the presence of particular mutations or variation in gene expression. Whole Genome Sequencing (WGS) is a biomarker test for analyzing the entire genome. WGS can provide more comprehensive diagnostic information, but it is also more expensive than other tests. In this study, System Dynamics and Game Theoretic models are employed to evaluate scenarios, and facilitate organizational decision making regarding WGS implementation. These models evaluate the clinical and economic value of WGS as well as its affordability and accessibility. The evaluated scenarios have covered the timing of implementing WGS using time to diagnosis and total cost.Comment: The IISE Annual Conference & Expo 202

Implementing competing risks in discrete event simulation:the event-specific probabilities and distributions approach

Background: Although several strategies for modelling competing events in discrete event simulation (DES) exist, a methodological gap for the event-specific probabilities and distributions (ESPD) approach when dealing with censored data remains. This study defines and illustrates the ESPD strategy for censored data. Methods: The ESPD approach assumes that events are generated through a two-step process. First, the type of event is selected according to some (unknown) mixture proportions. Next, the times of occurrence of the events are sampled from a corresponding survival distribution. Both of these steps can be modelled based on covariates. Performance was evaluated through a simulation study, considering sample size and levels of censoring. Additionally, an oncology-related case study was conducted to assess the ability to produce realistic results, and to demonstrate its implementation using both frequentist and Bayesian frameworks in R.Results: The simulation study showed good performance of the ESPD approach, with accuracy decreasing as sample sizes decreased and censoring levels increased. The average relative absolute error of the event probability (95%-confidence interval) ranged from 0.04 (0.00; 0.10) to 0.23 (0.01; 0.66) for 60% censoring and sample size 50, showing that increased censoring and decreased sample size resulted in lower accuracy. The approach yielded realistic results in the case study. Discussion: The ESPD approach can be used to model competing events in DES based on censored data. Further research is warranted to compare the approach to other modelling approaches for DES, and to evaluate its usefulness in estimating cumulative event incidences in a broader context. </p

Implementation of comparative effectiveness research in personalized medicine applications in oncology: current and future perspectives

Personalized medicine (PM) or precision medicine has been defined as an innovative approach that takes into account individual differences in people's genes, environments, and lifestyles in prevention and treatment of disease. In PM, genomic information may contribute to the molecular understanding of disease, to optimize preventive health care strategies, and to fit the best drug therapies to the patient's individual characteristics. Evidence development in the era of genomic medicine is extremely challenging due to a number of factors. These include the rapid technological innovation in molecular diagnostics and targeted drug discoveries, and hence the large number of mutations and multiple ways these may influence treatment decisions. Although the evidence base for PM is evolving rapidly, the main question to be explored in this article is whether existing evidence is also fit for comparative effectiveness research (CER). As a starting point, this paper therefore reflects on the evidence required for CER and the evidence gaps preventing decisions on market access and coverage. The paper then discusses challenges and potential barriers for applying a CER paradigm to PM, identifies common methodologies for designing clinical trials in PM, discusses various approaches for analyzing clinical trials to infer from population to individual level, and presents an example of a clinical trial in PM (The RxPONDER TRIAL) demonstrating good practice. The paper concludes with a future perspective, including modeling approaches for evidence synthesi

The influence of the reciprocal cable linkage in the advanced reciprocating gait orthosis on paraplegic gait performance

A wide variety of mechanical orthoses is available to provide ambulation to paraplegic patients. Evaluation of energy cost during walking in each of these devices has been acknowledged as an important topic in this field of research. In order to investigate the benefits of a ballistic swing on gait performance in the Advanced Reciprocating Gait Orthosis (ARGO) a study was conducted in which the ARGO was compared with an orthosis with freely swinging legs. This Non Reciprocally linked Orthosis (NRO) was obtained by removing the reciprocal linkage in the subjects' own ARGOs. Subsequently, flexion/extension limits were mounted to permit adjustment of stride length. Six male paraplegic subjects with lesions ranging from T4 to T12 were included in the study. A single case experimental design (B-A-B-A) was conducted in order to improve internal validity. Biomechanical and physiological parameters were assessed and the subjects' preference for either ARGO or NRO was determined.\ud \ud It was found that large inter-individual differences produced insufficient evidence in this study to draw general conclusions about difference in energy expenditure between both orthoses. However, individual analysis of the results showed a reduction of oxygen cost (range: 4%-14%) in the NRO in T9 and T12 lesions, while oxygen cost in subjects with T4 lesions increased markedly (22% and 40%). It is concluded that patients with low level lesions could benefit in terms of oxygen lost from removing the reciprocal cable linkage in the ARGO. However, only one subject preferred the NRO for walking, whereas none of the subject chose the NRO for use in daily living activities. Removal of the reciprocal cable linkage in the ARGO may not be desirable for these patients