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https://www.readbyqxmd.com/read/28239879/nonparametric-comparison-of-survival-functions-based-on-interval-censored-data-with-unequal-censoring
#1
Yanqin Feng, Ran Duan, Jianguo Sun
Nonparametric comparison of survival functions is one of the most commonly required task in failure time studies such as clinical trials, and for this, many procedures have been developed under various situations. This paper considers a situation that often occurs in practice but has not been discussed much: the comparison based on interval-censored data in the presence of unequal censoring. That is, one observes only interval-censored data, and the distributions of or the mechanisms behind censoring variables may depend on treatments and thus be different for the subjects in different treatment groups...
February 27, 2017: Statistics in Medicine
https://www.readbyqxmd.com/read/28239359/variations-in-hypoxia-impairs-muscle-oxygenation-and-performance-during-simulated-team-sport-running
#2
Alice J Sweeting, François Billaut, Matthew C Varley, Ramón F Rodriguez, William G Hopkins, Robert J Aughey
Purpose: To quantify the effect of acute hypoxia on muscle oxygenation and power during simulated team-sport running. Methods: Seven individuals performed repeated and single sprint efforts, embedded in a simulated team-sport running protocol, on a non-motorized treadmill in normoxia (sea-level), and acute normobaric hypoxia (simulated altitudes of 2,000 and 3,000 m). Mean and peak power was quantified during all sprints and repeated sprints. Mean total work, heart rate, blood oxygen saturation, and quadriceps muscle deoxyhaemoglobin concentration (assessed via near-infrared spectroscopy) were measured over the entire protocol...
2017: Frontiers in Physiology
https://www.readbyqxmd.com/read/28239247/bayesian-model-assessment-in-joint-modeling-of-longitudinal-and-survival-data-with-applications-to-cancer-clinical-trials
#3
Danjie Zhang, Ming-Hui Chen, Joseph G Ibrahim, Mark E Boye, Wei Shen
Joint models for longitudinal and survival data are routinely used in clinical trials or other studies to assess a treatment effect while accounting for longitudinal measures such as patient-reported outcomes (PROs). In the Bayesian framework, the deviance information criterion (DIC) and the logarithm of the pseudo marginal likelihood (LPML) are two well-known Bayesian criteria for comparing joint models. However, these criteria do not provide separate assessments of each component of the joint model. In this paper, we develop a novel decomposition of DIC and LPML to assess the fit of the longitudinal and survival components of the joint model, separately...
2017: Journal of Computational and Graphical Statistics
https://www.readbyqxmd.com/read/28239239/identifying-subgroups-of-enhanced-predictive-accuracy-from-longitudinal-biomarker-data-using-tree-based-approaches-applications-to-fetal-growth
#4
Jared C Foster, Danping Liu, Paul S Albert, Aiyi Liu
Longitudinal monitoring of biomarkers is often helpful for predicting disease or a poor clinical outcome. In this paper, We consider the prediction of both large and small-for-gestational-age births using longitudinal ultrasound measurements, and attempt to identify subgroups of women for whom prediction is more (or less) accurate, should they exist. We propose a tree-based approach to identifying such subgroups, and a pruning algorithm which explicitly incorporates a desired type-I error rate, allowing us to control the risk of false discovery of subgroups...
January 2017: Journal of the Royal Statistical Society. Series A, (Statistics in Society)
https://www.readbyqxmd.com/read/28239142/computational-analysis-of-intra-ventricular-flow-pattern-under-partial-and-full-support-of-bjut-ii-vad
#5
Qi Zhang, Bin Gao, Yu Chang
BACKGROUND Partial support, as a novel support mode, has been widely applied in clinical practice and widely studied. However, the precise mechanism of partial support of LVAD in the intra-ventricular flow pattern is unclear. MATERIAL AND METHODS In this study, a patient-specific left ventricular geometric model was reconstructed based on CT data. The intra-ventricular flow pattern under 3 simulated conditions - "heart failure", "partial support", and "full support" - were simulated by using fluid-structure interaction (FSI)...
February 27, 2017: Medical Science Monitor: International Medical Journal of Experimental and Clinical Research
https://www.readbyqxmd.com/read/28238953/cost-effectiveness-of-screening-patients-with-gastroesophageal-reflux-disease-for-barrett-s-esophagus-with-a-minimally-invasive-cell-sampling-device
#6
Curtis R Heberle, Amir-Houshang Omidvari, Ayman Ali, Sonja Kroep, Chung Yin Kong, John M Inadomi, Joel H Rubenstein, Angela C Tramontano, Emily C Dowling, William D Hazelton, E Georg Luebeck, Iris Lansdorp-Vogelaar, Chin Hur
BACKGROUND & AIMS: It is important to identify patients with Barrett's esophagus (BE), the precursor to esophageal adenocarcinoma (EAC). Patients with BE are usually identified by endoscopy, which is expensive. The cytosponge, which collects tissue from the esophagus non-invasively, could be a cost-effective tool for screening individuals with gastroesophageal reflux disease (GERD), who are at increased risk for BE. We developed a model to analyze the cost effectiveness of using cytosponge in first-line screening of patients with GERD for BE with endoscopic confirmation, compared to endoscopy screening only, METHODS: We incorporated data from a large clinical trial of cytosponge performance into 2 validated microsimulation models of EAC progression (the esophageal adenocarcinoma model from the Massachusetts General Hospital and the microsimulation screening analysis model from Erasmus University Medical Center)...
February 23, 2017: Clinical Gastroenterology and Hepatology
https://www.readbyqxmd.com/read/28238422/a-reduced-order-model-for-wall-shear-stress-in-abdominal-aortic-aneurysms-by-proper-orthogonal-decomposition
#7
Gary Han Chang, Clemens M Schirmer, Yahya Modarres-Sadeghi
In this paper, we introduce a method to construct a Reduced-Order Model (ROM) to study the physiological flow and the Wall Shear Stress (WSS) conditions in Abdominal Aortic Aneurysms (AAA). We start the process by running a training case using Computational Fluid Dynamics (CFD) simulations with time-varying flow parameters, such that these parameters cover the range of parameters that we would like to consider in our ROM. We use the inflow angle as the variable parameter in the current study. Then we use the snapshot Proper Orthogonal Decomposition (POD) to construct the reduced-order bases, which are subsequently enhanced using a QR-factorization technique to satisfy the relevant fluid boundary conditions...
February 2, 2017: Journal of Biomechanics
https://www.readbyqxmd.com/read/28238209/a-two-phase-model-for-chronic-disease-processes-under-intermittent-inspection
#8
Ying Wu, Richard J Cook
A model is developed for chronic diseases with an indolent phase that is followed by a phase with more active disease resulting in progression and damage. The time scales for the intensity functions for the active phase are more naturally based on the time since the start of the active phase, corresponding to a semi-Markov formulation. This two-phase model enables one to fit a separate regression model for the duration of the indolent phase and intensity-based models for the more active second phase. In cohort studies for which the disease status is only known at a series of clinical assessment times, transition times are interval-censored, which means the time origin for phase II is interval-censored...
February 26, 2017: Statistics in Medicine
https://www.readbyqxmd.com/read/28238045/estimation-of-the-cumulative-incidence-function-under-multiple-dependent-and-independent-censoring-mechanisms
#9
Judith J Lok, Shu Yang, Brian Sharkey, Michael D Hughes
Competing risks occur in a time-to-event analysis in which a patient can experience one of several types of events. Traditional methods for handling competing risks data presuppose one censoring process, which is assumed to be independent. In a controlled clinical trial, censoring can occur for several reasons: some independent, others dependent. We propose an estimator of the cumulative incidence function in the presence of both independent and dependent censoring mechanisms. We rely on semi-parametric theory to derive an augmented inverse probability of censoring weighted (AIPCW) estimator...
February 25, 2017: Lifetime Data Analysis
https://www.readbyqxmd.com/read/28237912/vestibular-stimulation-improves-insight-into-illness-in-schizophrenia-spectrum-disorders
#10
Philip Gerretsen, David D Pothier, Carolyn Falls, Maxine Armstrong, Thushanthi Balakumar, Hiroyuki Uchida, David C Mamo, Bruce G Pollock, Ariel Graff-Guerrero
Impaired insight into illness (IMP-INS) is common among individuals with schizophrenia spectrum disorders (SSD), contributing to medication nonadherence and poor clinical outcomes. Caloric vestibular simulation (CVS) is typically used to assess peripheral vestibular system function. Left cold CVS is also a transiently effective treatment for IMP-INS and hemineglect secondary to right brain hemisphere stroke, and possibly for IMP-INS and mood stabilization in patients with SSD. Participants with SSD and moderate-to-severe IMP-INS participated in an exploratory double blind, crossover, randomized controlled study of the effects of CVS on IMP-INS...
February 13, 2017: Psychiatry Research
https://www.readbyqxmd.com/read/28237830/a-need-to-revisit-clinical-breakpoints-of-tigecycline-effect-of-atypical-non-linear-plasma-protein-binding
#11
Ravi Shankar Prasad Singh, Jatinder Kaur Mukker, Stefanie K Drescher, Amelia N Deitchman, Hartmut Derendorf
Tigecycline is highly active against various drug-resistant bacteria. The US Food and Drug Administration (FDA) recently issued a black box warning for tigecycline owing to an associated increase in all-cause mortality. Clinical breakpoints of antibiotics are vital in susceptibility testing of pathogens for the selection of antibiotic therapy; however, no consensus exists between different committees on the clinical breakpoints of tigecycline. Of note, tigecycline exhibits atypical non-linear plasma protein binding (PPB) behaviour, and the pivotal probability of target attainment (PTA) analysis for the determination of clinical breakpoints did not account for the PPB of tigecycline...
February 22, 2017: International Journal of Antimicrobial Agents
https://www.readbyqxmd.com/read/28237430/evaluation-of-impact-of-an-external-breast-shield-flexishield-in-electronic-brachytherapy-for-breast-iort-a-phantom-study
#12
Yongbok Kim, Jason Wei-Yeong Huynh, Victor J Gonzalez
PURPOSE: To investigate Axxent (iCAD, Inc., San Jose, CA) electronic brachytherapy balloon deformation and its dosimetric impact because of an external flexible shield (FlexiShield [FS]; iCAD, Inc.). METHODS AND MATERIALS: Prostheses breast tissue phantom overlaid three spherical balloon applicators to simulate three clinical scenarios depending on minimum skin-to-balloon surface spacing (SS): balloon with SS of 2 cm, 1 cm, and balloon with 1 cm SS and touching the chest wall...
February 23, 2017: Brachytherapy
https://www.readbyqxmd.com/read/28237408/why-teaching-empathy-is-important-for-the-medical-degree
#13
N Díez-Goñi, M C Rodríguez-Díez
Empathy is a basic skill in the exercise of medicine and increases patient and physician satisfaction and improves clinical results. However, the teaching of empathy is poorly covered in the teaching plans. A number of studies have observed a reduction in empathy during the final training courses. The reasons for this decline include, the students' excessive academic workload, the prioritisation of acquiring medical expertise over humanistic knowledge, the patient load in hospitals and health centres and the physicians' need to distance themselves from their patients...
February 23, 2017: Revista Clínica Española
https://www.readbyqxmd.com/read/28237241/stochastic-bio-economic-modeling-of-mastitis-in-ethiopian-dairy-farms
#14
Abraham Mekibeb Getaneh, Sefinew Alemu Mekonnen, Henk Hogeveen
Mastitis is an inflammation of the mammary gland that is considered to be one of the most frequent and costly diseases in the dairy industry. Also in Ethiopia, bovine mastitis is one of the most frequently encountered diseases of dairy cows. However, there was no study, so far, regarding the costs of clinical mastitis and only two studies were reported on costs of subclinical mastitis. Presenting an appropriate and complete study of the costs of mastitis will help farmers in making management decisions for mastitis control...
March 1, 2017: Preventive Veterinary Medicine
https://www.readbyqxmd.com/read/28237207/the-probabilistic-efficiency-frontier-a-framework-for-cost-effectiveness-analysis-in-germany-put-into-practice-for-hepatitis-c-treatment-options
#15
Axel C Mühlbacher, Andrew Sadler
BACKGROUND: The German Institute for Quality and Efficiency in Health Care (Institut für Qualität und Wirtschaftlichkeit im Gesundheitswesen) adapted the efficiency frontier (EF) approach to conform to statutory provisions on cost-effectiveness analysis of health technologies. EF serves as a framework for evaluating cost-effectiveness and indirectly for pricing and reimbursement decisions. OBJECTIVES: To calculate an EF on the basis of single multidimensional benefit by taking patient preferences and uncertainty into account; to evaluate whether EF is useful to inform decision makers about cost-effectiveness of new therapies; and to find whether a treatment is efficient at given prices demonstrated through a case study on chronic hepatitis C...
February 2017: Value in Health: the Journal of the International Society for Pharmacoeconomics and Outcomes Research
https://www.readbyqxmd.com/read/28237081/incidence-of-posterior-interosseous-nerve-trauma-during-creation-of-the-3-4-wrist-arthroscopy-portal-in-cadavers
#16
Andre Eu-Jin Cheah, Wei Le, Jeffrey Yao
PURPOSE: To describe histologic evidence of nerve trauma during the creation and use of the 3-4 portal. METHODS: Fourteen fresh-frozen cadaveric wrists were mounted on a custom-built frame that simulated a wrist arthroscopy traction tower. After the 3-4 portal was created in the usual manner, the skin was dissected off to identify possible trauma to the posterior interosseous nerve (PIN). Specimens were categorized into those where there was clearly no trauma to the PIN and those where trauma was possible...
February 22, 2017: Arthroscopy: the Journal of Arthroscopic & related Surgery
https://www.readbyqxmd.com/read/28236658/targeted-dose-enhancement-in-radiotherapy-for-breast-cancer-using-gold-nanoparticles-part-2-a-treatment-planning-study
#17
Lidia Strigari, Veronica Ferrero, Giovanni Visonà, Piergiorgio Cerello, Andrea Attili, Sonja Visentin
PURPOSE: In recent years there has been growing interest in the use of gold nanoparticles (GNPs) combined with radiotherapy to improve tumor control. However, the complex interplay between GNP uptake and dose distribution in realistic clinical treatment are still somewhat unknown. METHODS: The effects of different concentrations of 2 nm diameter GNP, ranging from 0 to 5x10(5) nanoparticles per tumoral cell, were theoretically investigated. A parametrization of the GNP distribution outside the target was carried out using a Gaussian standard deviation σ, from a zero value, relative to a selective concentration of GNPs inside the tumor volume alone, to 50 mm, when GNPs are spatially distributed also in the healthy tissues surrounding the tumor...
February 25, 2017: Medical Physics
https://www.readbyqxmd.com/read/28236655/targeted-dose-enhancement-in-radiotherapy-for-breast-cancer-using-gold-nanoparticles-part-1-a-radiobiological-model-study
#18
Veronica Ferrero, Giovanni Visonà, Federico Dalmasso, Andrea Gobbato, Piergiorgio Cerello, Andrea Attili, Lidia Strigari, Sonja Visentin
PURPOSE: Gold nanoparticles (GNPs) are being proposed in combination with radiotherapy to improve tumor control. However, the exact mechanisms underlying GNP radiosensitization are yet to be understood, thus, we present a new approach to estimate the nanoparticle-driven increase in radiosensitivity. METHODS: A stochastic radiobiological model derived from the Local Effect Model (LEM) was coupled with Monte Carlo simulations performed using to estimate the increase in radiosensitivity due to the local dose deposited by secondary electrons produced from the interaction between the photons and GNPs at a nanometric level...
February 25, 2017: Medical Physics
https://www.readbyqxmd.com/read/28236647/effect-of-on-site-training-on-the-accuracy-of-blood-loss-estimation-in-a-simulated-obstetrics-environment
#19
Ikechukwu I Mbachu, Gerald O Udigwe, Chukwuemeka O Ezeama, George U Eleje, Ahizechukwu C Eke
OBJECTIVE: To determine the effect of on-site training on the accuracy of blood loss estimation in a simulated obstetrics environment. METHODS: In a tertiary hospital in Nigeria, clinical scenarios were created in April 2013 using known blood volumes in an objective structured clinical examination fashion. Doctors and nurses who worked in the obstetrics unit observed and recorded the blood volume at different clinical stations (first study stage). Subsequently, the actual amount of blood was revealed, followed by on-site training on the volume capacities of the study instruments...
February 25, 2017: International Journal of Gynaecology and Obstetrics
https://www.readbyqxmd.com/read/28236643/selection-of-indigenous-lactobacillus-paracasei-cd4-and-lactobacillus-gastricus-btm-7-as-probiotic-assessment-of-traits-combined-with-principal-component-analysis
#20
Kavita Sharma, Rishi Mahajan, Sampan Attri, Gunjan Goel
AIMS: The population of Himalayan region is known to consume variety of fermented and non fermented foods and as a result they have been benefited in terms of overall health, because of the associated beneficial microbes. Therefore, the focus of the present study was to identify new strains of Lactic Acid Bacteria (LAB) from dairy products such as milk (cow, goat, buffalo) and fermented products (curd and buttermilk) with properties suitable for use as probiotic cultures. METHODS AND RESULTS: A total of 75 isolates tentatively identified as LAB from 100 samples were initially screened for production of β-hemolysin as indicators of virulence which resulted in 38 isolates with no haemolytic activity...
February 25, 2017: Journal of Applied Microbiology
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