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https://www.readbyqxmd.com/read/28324918/statistical-consequences-of-a-successful-lung-allocation-system-recovering-information-and-reducing-bias-in-models-for-urgency
#1
Nabihah Tayob, Susan Murray
The lung allocation system has reduced the number of waitlist deaths by ranking transplant candidates on the basis of a lung allocation score that requires estimation of the current 1-year restricted mean waitlist survival (urgency). Fewer waitlist deaths and the systematic removal of candidates from the waitlist for transplantation present statistical challenges that must be addressed when using recent waitlist data. Multiple overlapping 1-year follow-up windows are used in a restricted mean model that estimates patient urgency on the basis of updated risk factors at the start of the window...
March 21, 2017: Statistics in Medicine
https://www.readbyqxmd.com/read/28319455/joint-model-imputation-to-estimate-the-treatment-effect-on-long-term-survival-using-auxiliary-events
#2
Audrey Mauguen, Stefan Michiels, Virginie Rondeau
Clinical trial duration may be a concern in clinical research, especially in cancer trials where the endpoint is overall survival. A surrogate endpoint can be used as an auxiliary variable to analyze the treatment effect earlier. At an early time point, the high number of censored observations can be compensated by the imputation of the unobserved deaths times. We propose to use predictions of the risk of death from a joint model for a recurrent event and a terminal event, which account for disease relapse information...
February 16, 2017: Journal of Biopharmaceutical Statistics
https://www.readbyqxmd.com/read/28318757/-imputing-missing-data-in-public-health-general-concepts-and-application-to-dichotomous-variables
#3
Gilma Hernández, David Moriña, Albert Navarro
The presence of missing data in collected variables is common in health surveys, but the subsequent imputation thereof at the time of analysis is not. Working with imputed data may have certain benefits regarding the precision of the estimators and the unbiased identification of associations between variables. The imputation process is probably still little understood by many non-statisticians, who view this process as highly complex and with an uncertain goal. To clarify these questions, this note aims to provide a straightforward, non-exhaustive overview of the imputation process to enable public health researchers ascertain its strengths...
March 15, 2017: Gaceta Sanitaria
https://www.readbyqxmd.com/read/28318323/sublingual-transdermal-and-intravenous-patient-controlled-analgesia-for-acute-post-operative-pain-systematic-literature-review-and-mixed-treatment-comparison
#4
Pablo Katz, Shweta Takyar, Pamela Palmer, Hiltrud Liedgens
OBJECTIVE: To conduct a systematic literature review (SLR) and quantitative analysis to assess the comparative efficacy and safety of the sufentanil sublingual tablet system (SSTS) against other available patient controlled analgesia (PCA) options for post-operative analgesia. METHODS: An SLR was conducted for studies published between 2004 and 2016. Due to study heterogeneity, subgroup analyses were conducted controlling for differences in imputation methods for missing values, baseline pain severity, and type of surgery...
March 20, 2017: Current Medical Research and Opinion
https://www.readbyqxmd.com/read/28317600/hla-imputation-what-is-it-good-for
#5
EDITORIAL
Diogo Meyer, Kelly Nunes
No abstract text is available yet for this article.
March 2017: Human Immunology
https://www.readbyqxmd.com/read/28315607/correcting-bias-due-to-missing-stage-data-in-the-non-parametric-estimation-of-stage-specific-net-survival-for-colorectal-cancer-using-multiple-imputation
#6
Milena Falcaro, James R Carpenter
BACKGROUND: Population-based net survival by tumour stage at diagnosis is a key measure in cancer surveillance. Unfortunately, data on tumour stage are often missing for a non-negligible proportion of patients and the mechanism giving rise to the missingness is usually anything but completely at random. In this setting, restricting analysis to the subset of complete records gives typically biased results. Multiple imputation is a promising practical approach to the issues raised by the missing data, but its use in conjunction with the Pohar-Perme method for estimating net survival has not been formally evaluated...
March 15, 2017: Cancer Epidemiology
https://www.readbyqxmd.com/read/28303087/a-pilot-genome-wide-association-study-identifies-potential-metabolic-pathways-involved-in-tinnitus
#7
Annick Gilles, Guy Van Camp, Paul Van de Heyning, Erik Fransen
Tinnitus, the perception of an auditory phantom sound in the form of ringing, buzzing, roaring, or hissing in the absence of an external sound source, is perceived by ~15% of the population and 2.5% experiences a severely bothersome tinnitus. The contribution of genes on the development of tinnitus is still under debate. The current manuscript reports a pilot Genome Wide Association Study (GWAS) into tinnitus, in a small cohort of 167 independent tinnitus subjects, and 749 non-tinnitus controls, who were collected as part of a cross-sectional study...
2017: Frontiers in Neuroscience
https://www.readbyqxmd.com/read/28301549/a-comprehensive-survey-of-genetic-variation-in-20-691-subjects-from-four-large-cohorts
#8
Sara Lindström, Stephanie Loomis, Constance Turman, Hongyan Huang, Jinyan Huang, Hugues Aschard, Andrew T Chan, Hyon Choi, Marilyn Cornelis, Gary Curhan, Immaculata De Vivo, A Heather Eliassen, Charles Fuchs, Michael Gaziano, Susan E Hankinson, Frank Hu, Majken Jensen, Jae H Kang, Christopher Kabrhel, Liming Liang, Louis R Pasquale, Eric Rimm, Meir J Stampfer, Rulla M Tamimi, Shelley S Tworoger, Janey L Wiggs, David J Hunter, Peter Kraft
The Nurses' Health Study (NHS), Nurses' Health Study II (NHSII), Health Professionals Follow Up Study (HPFS) and the Physicians Health Study (PHS) have collected detailed longitudinal data on multiple exposures and traits for approximately 310,000 study participants over the last 35 years. Over 160,000 study participants across the cohorts have donated a DNA sample and to date, 20,691 subjects have been genotyped as part of genome-wide association studies (GWAS) of twelve primary outcomes. However, these studies utilized six different GWAS arrays making it difficult to conduct analyses of secondary phenotypes or share controls across studies...
2017: PloS One
https://www.readbyqxmd.com/read/28296257/randomized-controlled-trial-of-rituximab-and-cost-effectiveness-analysis-in-treating-fatigue-and-oral-dryness-in-primary-sjogren-s-syndrome
#9
Simon J Bowman, Colin C Everett, John L O'Dwyer, Paul Emery, Costantino Pitzalis, Wan-Fai Ng, Colin T Pease, Elizabeth J Price, Nurhan Sutcliffe, Nagui St Gendi, Frances C Hall, Sharon P Ruddock, Catherine Fernandez, Catherine Reynolds, Claire T Hulme, Kevin A Davies, Christopher J Edwards, Peter C Lanyon, Robert J Moots, Euthalia Roussou, Ian P Giles, Linda D Sharples, Michele Bombardieri
OBJECTIVE: We investigated whether rituximab, an anti-B-cell therapy, improved symptoms of fatigue and oral dryness in patients with Primary Sjögren's Syndrome (PSS). METHODS: Multicentre, randomised, double-blind, parallel-group placebo-controlled trial, including Health Economic Analysis. Anti-Ro positive patients with PSS, symptomatic fatigue and oral dryness were recruited from 25 UK rheumatology clinics from August 2011 to January 2014. Patients were centrally-randomised to either placebo IV or rituximab IV (1000mg in 250mL) at weeks 0, 2, 24 and 26, with pre-and post-infusion medication including corticosteroids...
March 10, 2017: Arthritis & Rheumatology
https://www.readbyqxmd.com/read/28294286/augmented-estimation-for-t-year-survival-with-censored-regression-models
#10
Yu Zheng, Tianxi Cai
Reliable and accurate risk prediction is fundamental for successful management of clinical conditions. Estimating comprehensive risk prediction models precisely, however, is a difficult task, especially when the outcome of interest is time to a rare event and the number of candidate predictors, p, is not very small. Another challenge in developing accurate risk models arises from potential model misspecification. Time-specific generalized linear models estimated with inverse censoring probability weighting are robust to model misspecification, but may be inefficient in the rare event setting...
March 10, 2017: Biometrics
https://www.readbyqxmd.com/read/28293776/long-term-outcomes-of-treat-to-target-strategy-in-established-rheumatoid-arthritis-a-daily-practice-prospective-cohort-study
#11
Nicole Pamplona Bueno de Andrade, Rafael Mendonça da Silva Chakr, Ricardo Machado Xavier, Daniela Viecceli, Ricardo Henrique Bilycz Correa, Cilomar Martins de Oliveira Filho, Claiton Viegas Brenol
To examine disease activity and physical function after implementation of treat-to-target (T2T) strategy in patients with established rheumatoid arthritis (RA) over a long-term period. Patients with RA were started on a T2T strategy in 2005 and followed through 2014. Patients were seen every 3-4 months until remission/low disease activity was achieved and every 6 months thereafter. Disease activity was measured by the DAS28 and CDAI, and physical function by the HAQ-DI. Results were presented as all observed data, without imputation for missing values...
March 14, 2017: Rheumatology International
https://www.readbyqxmd.com/read/28293630/metabolomic-biomarker-identification-in-presence-of-outliers-and-missing-values
#12
Nishith Kumar, Md Aminul Hoque, Md Shahjaman, S M Shahinul Islam, Md Nurul Haque Mollah
Metabolomics is the sophisticated and high-throughput technology based on the entire set of metabolites which is known as the connector between genotypes and phenotypes. For any phenotypic changes, potential metabolite (biomarker) identification is very important because it provides diagnostic as well as prognostic markers and can help to develop new biomolecular therapy. Biomarker identification from metabolomics data analysis is hampered by the use of high-throughput technology that provides high dimensional data matrix which contains missing values as well as outliers...
2017: BioMed Research International
https://www.readbyqxmd.com/read/28289475/combined-genome-wide-linkage-and-targeted-association-analysis-of-head-circumference-in-autism-spectrum-disorder-families
#13
M Woodbury-Smith, D A Bilder, J Morgan, L Jerominski, T Darlington, T Dyer, A D Paterson, H Coon
BACKGROUND: It has long been recognized that there is an association between enlarged head circumference (HC) and autism spectrum disorder (ASD), but the genetics of HC in ASD is not well understood. In order to investigate the genetic underpinning of HC in ASD, we undertook a genome-wide linkage study of HC followed by linkage signal targeted association among a sample of 67 extended pedigrees with ASD. METHODS: HC measurements on members of 67 multiplex ASD extended pedigrees were used as a quantitative trait in a genome-wide linkage analysis...
2017: Journal of Neurodevelopmental Disorders
https://www.readbyqxmd.com/read/28288072/dissecting-leapfrog-how-well-do-leapfrog-safe-practices-scores-correlate-with-hospital-compare-ratings-and-penalties-and-how-much-do-they-matter
#14
Shawna N Smith, Heidi A Reichert, Jessica M Ameling, Jennifer Meddings
BACKGROUND: Voluntary Leapfrog Safe Practices Score (SPS) measures were among the first public reports of hospital performance. Recently, Medicare's Hospital Compare website has reported compulsory measures. Leapfrog's Hospital Safety Score (HSS) grades incorporate SPS and Medicare measures. We evaluate associations between Leapfrog SPS and Medicare measures, and the impact of SPS on HSS grades. METHODS: Using 2013 hospital data, we linked Leapfrog HSS data with central line-associated bloodstream infection (CLABSI) and catheter-associated urinary tract infection (CAUTI) standardized infection ratios (SIRs), and Hospital Readmission and Hospital-Acquired Condition (HAC) Reduction Program penalties incorporating 2013 performance...
March 10, 2017: Medical Care
https://www.readbyqxmd.com/read/28287873/on-inference-of-control-based-imputation-for-analysis-of-repeated-binary-outcomes-with-missing-data
#15
Fei Gao, Guanghan Liu, Donglin Zeng, Guoqing Diao, Joseph F Heyse, Joseph G Ibrahim
Missing data are common in longitudinal clinical trials. How to handle missing data is critical for both sponsors and regulatory agencies to assess treatment effect from the trials. Recently, a control-based imputation has been proposed, where the missing data are imputed based on the assumption that patients who discontinued the test drug will have a similar response profile to the patients in the control group. Under control-based imputation, the variance estimation may be biased using Rubin's formula which could produce biased statistical inferences...
February 7, 2017: Journal of Biopharmaceutical Statistics
https://www.readbyqxmd.com/read/28286884/stability-weighted-matrix-completion-of-incomplete-multi-modal-data-for-disease-diagnosis
#16
Kim-Han Thung, Ehsan Adeli, Pew-Thian Yap, Dinggang Shen
Effective utilization of heterogeneous multi-modal data for Alzheimer's Disease (AD) diagnosis and prognosis has always been hampered by incomplete data. One method to deal with this is low-rank matrix completion (LRMC), which simultaneous imputes missing data features and target values of interest. Although LRMC yields reasonable results, it implicitly weights features from all the modalities equally, ignoring the differences in discriminative power of features from different modalities. In this paper, we propose stability-weighted LRMC (swLRMC), an LRMC improvement that weights features and modalities according to their importance and reliability...
October 2016: Medical Image Computing and Computer-assisted Intervention: MICCAI ..
https://www.readbyqxmd.com/read/28283553/genome-wide-association-study-of-sepsis-in-extremely-premature-infants
#17
Lakshmi Srinivasan, Grier Page, Haresh Kirpalani, Jeffrey C Murray, Abhik Das, Rosemary D Higgins, Waldemar A Carlo, Edward F Bell, Ronald N Goldberg, Kurt Schibler, Beena G Sood, David K Stevenson, Barbara J Stoll, Krisa P Van Meurs, Karen J Johnson, Joshua Levy, Scott A McDonald, Kristin M Zaterka-Baxter, Kathleen A Kennedy, Pablo J Sánchez, Shahnaz Duara, Michele C Walsh, Seetha Shankaran, James L Wynn, C Michael Cotten
OBJECTIVE: To identify genetic variants associated with sepsis (early-onset and late-onset) using a genome-wide association (GWA) analysis in a cohort of extremely premature infants. STUDY DESIGN: Previously generated GWA data from the Neonatal Research Network's anonymised genomic database biorepository of extremely premature infants were used for this study. Sepsis was defined as culture-positive early-onset or late-onset sepsis or culture-proven meningitis. Genomic and whole-genome-amplified DNA was genotyped for 1...
March 10, 2017: Archives of Disease in Childhood. Fetal and Neonatal Edition
https://www.readbyqxmd.com/read/28282397/evaluation-of-the-performance-of-national-health-systems-in-2004-2011-an-analysis-of-173-countries
#18
Daxin Sun, Haksoon Ahn, Tomas Lievens, Wu Zeng
In an effort to improve health service delivery and achieve better health outcomes, the World Health Organization (WHO) has called for improved efficiency of health care systems to better use the available funding. This study aims to examine the efficiency of national health systems using longitudinal country-level data. Data on health spending per capita, infant mortality rate (IMR), under 5 mortality rate (U5MR), and life expectancy (LE) were collected from or imputed for 173 countries from 2004 through 2011...
2017: PloS One
https://www.readbyqxmd.com/read/28281121/short-term-outcomes-of-laparoscopic-vs-open-liver-resection-for-hepatocellular-adenoma-a-multicenter-propensity-score-adjustment-analysis-by-the-afc-hca-2013-study-group
#19
Filippo Landi, Nicola De' Angelis, Olivier Scatton, Xavier Vidal, Ahmet Ayav, Fabrice Muscari, Safi Dokmak, Guido Torzilli, Nicolas Demartines, Olivier Soubrane, Daniel Cherqui, Jean Hardwigsen, Alexis Laurent
BACKGROUND: Patients with hepatocellular adenomas are, in selected cases, candidates for liver resection, which can be approached via laparoscopy or laparotomy. The present study aimed to investigate the effects of the surgical approach on the postoperative morbidities of both minor and major liver resections. METHODS: In this multi-institutional study, all patients who underwent open or laparoscopic hepatectomies for hepatocellular adenomas between 1989 and 2013 in 27 European centers were retrospectively reviewed...
March 9, 2017: Surgical Endoscopy
https://www.readbyqxmd.com/read/28280520/linking-lung-airway-structure-to-pulmonary-function-via-composite-bridge-regression
#20
Kun Chen, Eric A Hoffman, Indu Seetharaman, Feiran Jiao, Ching-Long Lin, Kung-Sik Chan
The human lung airway is a complex inverted tree-like structure. Detailed airway measurements can be extracted from MDCT-scanned lung images, such as segmental wall thickness, airway diameter, parent-child branch angles, etc. The wealth of lung airway data provides a unique opportunity for advancing our understanding of the fundamental structure-function relationships within the lung. An important problem is to construct and identify important lung airway features in normal subjects and connect these to standardized pulmonary function test results such as FEV1%...
December 2016: Annals of Applied Statistics
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