Search results for "multivariate"

Prenatal exposure to traffic-related air pollution and fetal growth in a cohort of pregnant women

2012

Objectives Scant evidence is available on effects of air pollution on longitudinally measured fetal biometry, and thus it remains unclear as to whether there are critical windows of exposure or specificity of effects. Our objective was to examine the association between exposure to nitrogen dioxide (NO2) during pregnancy and fetal and neonatal anthropometry in a cohort of Spanish women. Methods Temporally adjusted land-use regression was used to estimate exposure to NO2 at home addresses. Biparietal diameter (BPD), abdominal circumference (AC), femur length (FL) and estimated fetal weight (EFW) were evaluated in each trimester by ultrasound. As neonatal outcomes, weight, length and head cir…

It is time to abandon “Expected bladder capacity.” Systematic review and new models for children's normal maximum voided volumes

2013

Background There is an agreement to use simple formulae (expected bladder capacity and other age based linear formulae) as bladder capacity benchmark. But real normal child's bladder capacity is unknown. Aims To offer a systematic review of children's normal bladder capacity, to measure children's normal maximum voided volumes (MVVs), to construct models of MVVs and to compare them with the usual formulae. Methods Computerized, manual and grey literature were reviewed until February 2013. Epidemiological, observational, transversal, multicenter study. A consecutive sample of healthy children aged 5–14 years, attending Primary Care centres with no urologic abnormality were selected. Particip…

Leukocytosis and Thrombosis At Diagnosis Are Associated with Poor Survival in Polycythemia Vera: A Population-Based Study on 327 Patients

2011

Abstract Abstract 2819 Introduction Polycythemia Vera (PV) is a myeloproliferative neoplasm with a long life expectancy. Consequently, long-term follow-up studies that focus on survival of PV patients must be conducted in order to register a sufficient number of events to provide informative results and statistical analyses. Most of the published studies are single-institution that focused on patients referred to hospitals, which does not necessarily reflect the course of PV in the general population. In these studies, the median age at diagnosis is younger than usually noted for PV patients in population-based studies. Moreover, survival is generally based on observed mortality, a good but…

Socio-professional status as a major determinant of disparities in cardiovascular outcomes: contemporary data on the prognosis inof manual workersmen…

2013

Introduction: Over the last decade in France, the early prognosis after acute myocardial infarction (AMI) has markedly improved. However, recent work suggests persistent socioeconomic disparities in outcomes after AMI. From a regional population-based study, we analyzed the prognosis in manual workers after AMI. Patients: Patients recorded in the ObservatoiRe des Infarctus du myocarde de Cote d'Or (RICO) between 2001 and 2011, < 65 y, with a current professional activity and follow-up at one year. Socio-professional categories (SPC) were collected according to INSEE definition. The primary endpoint was combined mortality and hospitalization for heart failure. Results: Among the 1671 patient…

Penalized inference in multivariate ordered logistic models: theory and applications

2010

Cost-Effectiveness Analysis: Stress Ulcer Bleeding Prophylaxis with Proton Pump Inhibitors, H2 Receptor Antagonists

2012

Abstract Objectives Proton pump inhibitors (PPIs) and H2-receptor antagonists (H2RAs) present varying pharmacological efficacy in preventing stress ulcer bleeding (SUB) in intensive care units. The literature also reports disparate rates of ventilator-assisted pneumonia (VAP) as side effects of these treatments. We compared the cost-effectiveness of these two prophylactic pharmacological options. Methods We constructed a decision tree with a 60-day time horizon for patients at high risk for developing SUB, receiving either PPIs or H2RAs. For each treatment strategy, patients could be in one of three states of health: SUB, VAP, or no complication. Contemporary, clinically relevant probabilit…

Two-stage adaptive designs with correlated test statistics.

2005

When performing a trial using an adaptive sequential design, it is usually assumed that the data for each stage come from different units; for example, patients. However, sometimes it is not possible to satisfy this condition or to check whether it is satisfied. In these cases, the test statistics and p-values of each stage may be dependent. In this paper we investigate the type I error of two-stage adaptive designs when the test statistics from the stages are assumed to be bivariate normal. Analytical considerations are performed under the restriction that the conditional error function is constant in the continuation region. We show that the decisions can become conservative as well as an…

Multivariate equivalence tests for use in pharmaceutical development.

2014

Statistical equivalence analyses are well-established parts of many studies in the biomedical sciences. Also in pharmaceutical development and manufacturing equivalence testing methods are required in order to statistically establish similarities between machines, process components, or complete processes. This article presents a choice of multivariate equivalence testing procedures for normally distributed data as generalizations of existing univariate methods. In all derived methods, variability is interpreted as nuisance parameter. The use of the proposed methods in pharmaceutical development is demonstrated with a comparative analysis of dissolution profiles.

Knowledge of and attitudes to influenza in unvaccinated primary care physicians and nurses

2014

Primary healthcare workers, especially nurses, are exposed to the vast majority of patients with influenza and play an important role in vaccinating patients. Healthcare workers' misconceptions about influenza and influenza vaccination have been reported as possible factors associated with lack of vaccination. The objective of this study was to compare the characteristics of unvaccinated physicians and unvaccinated nurses in the 2011-2012 influenza season. We performed an anonymous web survey of Spanish primary healthcare workers in 2012. Information was collected on vaccination and knowledge of and attitudes to the influenza vaccine. Multivariate analysis was performed using unconditional …

Genetic Normalized Convolution

2011

Normalized convolution techniques operate on very few samples of a given digital signal and add missing information, trough spatial interpolation. From a practical viewpoint, they make use of data really available and approximate the assumed values of the missing information. The quality of the final result is generally better than that obtained by traditional filling methods as, for example, bilinear or bicubic interpolations. Usually, the position of the samples is assumed to be random and due to transmission errors of the signal. Vice versa, we want to apply normalized convolution to compress data. In this case, we need to arrange a higher density of samples in proximity of zones which c…