638 results match your criteria: "Institute of Statistical Mathematics[Affiliation]"

Aims: The effectiveness of pulmonary vein isolation (PVI) guided by VISITAG SURPOINT (VS) has been demonstrated in Western populations. However, data for Asian populations are limited. VS settings may differ for Asians, given their smaller body size.

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Adaptive Cohort Size Determination Method for Bayesian Optimal Interval Phase I/II Design to Shorten Clinical Trial Duration.

JCO Precis Oncol

July 2023

Biometrics Department, R&D Division, Kyowa Kirin Co, Ltd, Tokyo, Japan.

Purpose: Recently, the strategy for dose optimization in oncology has shifted toward conducting phase II randomized controlled trials with multiple doses. Optimal biologic dose (OBD) selection from phase I trial data to determine candidate doses for phase II trials has been gaining attention. Trials to identify the OBD have a fixed cohort size, which increases the trial duration.

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The identification of the transmission parameters of a virus is fundamental to identify the optimal public health strategy. These parameters can present significant changes over time caused by genetic mutations or viral recombination, making their continuous monitoring fundamental. Here we present a method, suitable for this task, which uses as unique information the daily number of reported cases.

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Identifying risk factors for adverse events of pyridoxal phosphate in infantile epileptic spasms syndrome.

Epilepsy Behav

August 2023

Division of Child Neurology, Department of Brain and Neurosciences, Faculty of Medicine, Tottori University, Yonago, Japan.

Introduction: Infantile epileptic spasms syndrome (IESS) is characterized by epileptic spasms, regardless of hypsarrhythmia on electroencephalogram or neurodevelopmental delay. In Japan, pyridoxal 5'-phosphate (PLP) is often used as the first-line treatment for IESS because it is effective in a certain number of patients. Although several studies have reported serious adverse events following PLP treatment, no study has investigated the risk factors for such occurrences.

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Background And Aims: Mechanical ventilation is associated with several risks, including barotrauma, ventilator-associated pneumonia, and ventilator-induced diaphragmatic dysfunction. A delay in weaning from mechanical ventilation increases these risks, and prolonged weaning has been shown to increase hospital mortality. Various tools have been used in clinical practice to predict successful weaning from mechanical ventilation; however, they have a low prognostic accuracy.

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Background: The Foods with Function Claims (FFC) was introduced in Japan in April 2015 to make more products available that are labeled with health functions. The products' functionality of function claims must be explained by scientific evidence presented in systematic reviews (SRs), but the quality of recent SRs is unclear. This study assessed the quality of SRs in the FFC registered on the Consumer Affairs Agency (CAA) website in Japan.

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Network meta-analysis is gaining prominence in clinical epidemiology and health technology assessments that enable comprehensive assessment of comparative effectiveness for multiple available treatments. In network meta-analysis, Bayesian methods have been one of the standard approaches for the arm-based approach and are widely applied in practical data analyses. Also, for most cases in these applications, proper noninformative priors are adopted, which does not incorporate subjective prior knowledge into the analyses, and reference Bayesian analyses are major choices.

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Article Synopsis
  • Network meta-analysis is crucial for comparing treatment effectiveness, but standard methods like REML often underestimate statistical errors in confidence intervals.
  • Recent improvements using higher-order asymptotic approximations offer better accuracy for these analyses, particularly with covariance matrix estimators.
  • Simulation studies showed that new Kenward-Roger-type methods provide more reliable coverage compared to traditional REML-based confidence intervals, as demonstrated in real dataset applications.
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Network meta-analysis has played an important role in evidence-based medicine for assessing the comparative effectiveness of multiple available treatments. The prediction interval has been one of the standard outputs in recent network meta-analysis as an effective measure that enables simultaneous assessment of uncertainties in treatment effects and heterogeneity among studies. To construct the prediction interval, a large-sample approximating method based on the t-distribution has generally been applied in practice; however, recent studies have shown that similar t-approximation methods for conventional pairwise meta-analyses can substantially underestimate the uncertainty under realistic situations.

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This research investigates the relationship between COVID-19 and urban factors in Tokyo. To understand the spread dynamics of COVID-19, the study examined 53 urban variables (including population density, socio-economic status, housing conditions, transportation, and land use) in 53 municipalities of Tokyo prefecture. Using spatial models, the study analysed the patterns and predictors of COVID-19 infection rates.

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The relation between earthquakes and volcanic eruptions, each of which is manifested by large-scale tectonic plate and mantle motions, has been widely discussed. Mount Fuji, in Japan, last erupted in 1707, paired with a magnitude (M)-9-class earthquake 49 days prior. Motivated by this pairing, previous studies investigated its effect on Mount Fuji after both the 2011 M9 Tohoku megaquake and a triggered M5.

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Stieltjes Transforms and -Transforms Associated with Two-Parameter Lambert-Tsallis Functions.

Entropy (Basel)

May 2023

Laboratoire de Mathématiques LAREMA, Université d'Angers, 2 boulevard Lavoisier, CEDEX 01, 49045 Angers, France.

In this paper, we study a two-parameter family of Stieltjes transformations related to holomorphic Lambert-Tsallis functions, which are a two-parameter generalization of the Lambert function. Such Stieltjes transformations appear in the study of eigenvalue distributions of random matrices associated with some growing statistically sparse models. A necessary and sufficient condition on the parameters is given for the corresponding functions being Stieltjes transformations of probabilistic measures.

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Introduction: In general, caesarean sections are performed under spinal anaesthesia. Hypotension after spinal anaesthesia adversely affects both the mother and fetus. Although several studies have used pulse oximetry-derived indices, such as pulse perfusion index (PI) and Pleth variability index (PVI), to predict hypotension after spinal anaesthesia, the predictive ability of the PI and PVI remain controversial.

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Background: There have been few studies reporting on maternal and neonatal events in high-risk pregnant women receiving medications for preventing hypertensive disorders of pregnancy (HDP).

Objective: To identify placental abruption, postpartum hemorrhage, neonatal intraventricular hemorrhage, and neonates with small for gestational age (SGA) or growth restriction resulting from medications for preventing HDP in high-risk pregnant women using a network meta-analysis.

Search Strategy: All randomized controlled trials comparing the most commonly used medications (antiplatelet agents, anticoagulants, antioxidants, nitric oxide, and calcium) for preventing HDP in high-risk pregnant women were searched from the Cochrane Pregnancy and Childbirth's Specialized Register of Controlled Trials until July 31, 2020, without language restriction.

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Multivariate epidemic count time series model.

PLoS One

June 2023

Department of Statistical Modeling, The Institute of Statistical Mathematics, Tachikawa, Tokyo, Japan.

An infectious disease spreads not only over a single population or community but also across multiple and heterogeneous communities. Moreover, its transmissibility varies over time because of various factors such as seasonality and epidemic control, which results in strongly nonstationary behavior. In conventional methods for assessing transmissibility trends or changes, univariate time-varying reproduction numbers are calculated without taking into account transmission across multiple communities.

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Data-dependent contrast test for dose-finding clinical trials.

Contemp Clin Trials

August 2023

Biometrics Department, R&D Division, Kyowa Kirin Co., Ltd. Otemachi Financial City Grand Cube, 1-9-2 Otemachi, Chiyoda-ku, Tokyo 100-004, Japan; Research Center for Medical and Health Data Science, The Institute of Statistical Mathematics, Tokyo, Japan. Electronic address:

We propose a simple and powerful data-dependent contrast test with ordinal-constraint contrast coefficients of the dose response determined from observed responses. The contrast coefficients are easily calculated using a pool-adjacent-violators algorithm and making assumptions for the contrast coefficients. Once the dose response is determined for p < 0.

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Purpose: In terms of medical policy for cervical cancer prevention, Japan lags far behind other industrialized countries. We initiated a randomized controlled trial to evaluate the self-sampling human papillomavirus (HPV) test as a tool to raise screening uptake and detection of pre-cancer. This study was conducted to explore the acceptability and preference of self-sampling using a subset of the data from this trial.

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Diagnostic accuracy of point-of-care ultrasound for shock: a systematic review and meta-analysis.

Crit Care

May 2023

Department of Health Data Science, Graduate School of Data Science, Yokohama City University, 22-2 Seto, Kanazawa, Yokohama, 236-0027, Japan.

Article Synopsis
  • Circulatory failure can be classified into four types of shock: obstructive, cardiogenic, distributive, and hypovolemic, and accurate identification is crucial for effective treatment; POCUS (point-of-care ultrasound) is a valuable tool for diagnosing these types.
  • A systematic literature review analyzed 1553 studies, focusing on 12 that met the inclusion criteria with a total of 1132 patients, evaluating the diagnostic accuracy of POCUS for each shock type.
  • The results showed high pooled sensitivity and specificity for diagnosing different shocks, with an area under the receiver operating characteristic curve around 0.95, indicating strong diagnostic performance, especially for obstructive shock, which had a positive likelihood ratio of 40. *
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Background: Cancer patients experience various forms of psychological distress. Their distress, mainly in the form of depression and anxiety, leads to poor quality of life, increased medical spending due to frequent visits, and decrease in treatment adherence. It is estimated that 30-50% among them would require support from mental health professionals: in reality, much less actually receive such support partly due to a shortage of qualified professionals and also due to psychological barriers in seeking such help.

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Background: We previously reported that standard deviation (SD) of systolic blood pressure (SBP), an index of BP variability, and SBP-time in target range (TTR), an index of BP consistency, were significantly associated with adverse events in patients with non-valvular atrial fibrillation (NVAF). Thus, this study aimed to compare predictive ability for adverse events among visit-to-visit BP variability/consistency indices using data from the J-RHYTHM Registry.

Methods: Of 7406 outpatients with NVAF, 7226 (age, 69.

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For predictive evaluation based on quasi-posterior distributions, we develop a new information criterion, the posterior covariance information criterion (PCIC). PCIC generalizes the widely applicable information criterion (WAIC) so as to effectively handle predictive scenarios where likelihoods for the estimation and the evaluation of the model may be different. A typical example of such scenarios is the weighted likelihood inference, including prediction under covariate shift and counterfactual prediction.

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Background: To examine the reasonable duration of continuous electrocardiographic monitoring (CEM) to detect AF at acute ischemic stroke.

Materials And Method: 811 consecutive patients admitted to Tsuruga Municipal Hospital by acute ischemic stroke between April 2013 and December 2021 were enrolled in this study. Excluding 78 patients, 733 patients were analyzed by cluster analysis with SurvCART algorithm, followed by Kaplan-Meier analysis.

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Introduction: Renin-angiotensin system (RAS) plays a key role in various types of cardiovascular disease and many kinds of RAS inhibitors have been developed. The effect of discontinuation of RAS inhibitors on clinical outcomes is still controversial. This study aims to evaluate the effects of discontinuing RAS inhibitor medication on the clinical outcomes of patients continuously taking these agents.

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