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Sample size calculation

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https://www.readbyqxmd.com/read/28323515/a-nested-group-sequential-framework-for-regional-evaluation-in-global-drug-development-program
#1
William Wang, Zhiwei Jiang, Jingjun Qiu, Jielai Xia, Xiang Guo
The primary objective of a multiregional clinical trial (MRCT) is to assess the efficacy of all participating regions and evaluate the probability of applying the overall results to a specific region. The consistency assessment of the target region with the overall results is the most common way of evaluating the efficacy in a specific region. Recently, Huang et al. (2012) proposed an additional trial in the target region to an MRCT to evaluate the efficacy in the target ethnic (TE) population under the framework of simultaneous global drug development program (SGDDP)...
February 10, 2017: Journal of Biopharmaceutical Statistics
https://www.readbyqxmd.com/read/28319460/power-and-sample-size-for-the-s-t-repeated-measures-design-combined-with-a-linear-mixed-effects-model-allowing-for-missing-data
#2
Toshiro Tango
Tango (Biostatistics 2016) proposed a new repeated measures design called the S:T repeated measures design, combined with generalized linear mixed-effects models and sample size calculations for a test of the average treatment effect that depend not only on the number of subjects but on the number of repeated measures before and after randomization per subject used for analysis. The main advantages of the proposed design combined with the generalized linear mixed-effects models are (1) it can easily handle missing data by applying the likelihood-based ignorable analyses under the missing at random assumption and (2) it may lead to a reduction in sample size compared with the simple pre-post design...
February 13, 2017: Journal of Biopharmaceutical Statistics
https://www.readbyqxmd.com/read/28318491/late-life-depression-hippocampal-volumes-and-hypothalamic-pituitary-adrenal-axis-regulation-a-systematic-review-and-meta-analysis
#3
Mirjam I Geerlings, Lotte Gerritsen
BACKGROUND: We systematically reviewed and meta-analyzed the association of late-life depression (LLD) with hippocampal volume (HCV) and total brain volume (TBV), and of cortisol levels with HCV, including subgroup analyses of depression characteristics and methodological aspects. METHODS: We searched PubMed and Embase for original studies that examined the cross-sectional relationship between LLD and HCV or TBV, and 46 studies fulfilled the inclusion criteria. Standardized mean differences (Hedges' g) between LLD and control subjects were calculated from crude or adjusted brain volumes using random effects...
January 27, 2017: Biological Psychiatry
https://www.readbyqxmd.com/read/28316192/-effect-of-optical-zone-diameter-on-corneal-biomechanical-properties-after-small-incision-lenticule-extraction
#4
P H Wei, Y Wang, H Li, R Dou, L Y Li, W Zhao, J M Zhang
Objective: To investigate the effect of optical zone diameter on corneal biomechanical properties after small incision lenticule extraction (SMILE). Methods: In this prospective case-control study, 62 eyes of 42 patients with myopia and myopic astigmatism that had undergone SMILE procedure were divided into 2 groups according to the optical zone (OZ) diameter: group A, 31 eyes of 19 patients, OZ= 6.5 mm; group B, 31eyes of 23 patients, OZ=6.0 mm. These patients were examined for corneal hysteresis (CH) and corneal resistance factor (CRF) with the Ocular Response Analyzer (ORA) preoperatively and at 1 week, 1 month and 3 months postoperatively; at the same time, the central corneal thickness-corrected indices of DifCH and DifCRF were calculated...
March 11, 2017: [Zhonghua Yan Ke za Zhi] Chinese Journal of Ophthalmology
https://www.readbyqxmd.com/read/28316055/a-comparison-of-accelerated-and-non-accelerated-mri-scans-for-brain-volume-and-boundary-shift-integral-measures-of-volume-change-evidence-from-the-adni-dataset
#5
Emily N Manning, Kelvin K Leung, Jennifer M Nicholas, Ian B Malone, M Jorge Cardoso, Jonathan M Schott, Nick C Fox, Josephine Barnes
The aim of this study was to assess whether the use of accelerated MRI scans in place of non-accelerated scans influenced brain volume and atrophy rate measures in controls and subjects with mild cognitive impairment and Alzheimer's disease. We used data from 861 subjects at baseline, 573 subjects at 6 months and 384 subjects at 12 months from the Alzheimer's Disease Neuroimaging Initiative (ADNI). We calculated whole-brain, ventricular and hippocampal atrophy rates using the k-means boundary shift integral (BSI)...
March 18, 2017: Neuroinformatics
https://www.readbyqxmd.com/read/28315880/an-analytic-solution-to-the-computation-of-power-and-sample-size-for-genetic-association-studies-under-a-pleiotropic-mode-of-inheritance
#6
Derek Gordon, Douglas Londono, Payal Patel, Wonkuk Kim, Stephen J Finch, Gary A Heiman
Our motivation here is to calculate the power of 3 statistical tests used when there are genetic traits that operate under a pleiotropic mode of inheritance and when qualitative phenotypes are defined by use of thresholds for the multiple quantitative phenotypes. Specifically, we formulate a multivariate function that provides the probability that an individual has a vector of specific quantitative trait values conditional on having a risk locus genotype, and we apply thresholds to define qualitative phenotypes (affected, unaffected) and compute penetrances and conditional genotype frequencies based on the multivariate function...
March 18, 2017: Human Heredity
https://www.readbyqxmd.com/read/28315877/the-value-of-lncrna-hulc-as-a-prognostic-factor-for-survival-of-cancer-outcome-a-meta-analysis
#7
Xian Chen, Limin Lun, Huabin Hou, Runhua Tian, Haiping Zhang, Yunyuan Zhang
AIMS: Growing evidence from recent studies has shown that lncRNA HULC plays a role in the development of multiple carcinomas. This meta-analysis aimed to analyze available data to identify the prognostic value of HULC in multiple tumors. METHODS: A systematic search was performed by using PubMed (medline), Embase, ISI Web of Knowledge, Springer, the Cochrane Library, Scopus, BioMed Central, ScienceDirect, Wanfang, Weipu, and China National Knowledge Internet (CNKI) computerized databases from inception to Nov 30, 2016...
March 17, 2017: Cellular Physiology and Biochemistry
https://www.readbyqxmd.com/read/28315760/medication-adherence-outcomes-of-771-intervention-trials-systematic-review-and-meta-analysis
#8
REVIEW
Vicki S Conn, Todd M Ruppar
Excellent medication adherence contributes to decreases in morbidity, mortality, and health care costs. Although researchers have tested many interventions to increase adherence, results are sometimes conflicting and often unclear. This systematic review applied meta-analytic procedures to integrate primary research that tested medication adherence interventions. Comprehensive searching completed in 2015 located 771 published and unpublished intervention studies with adherence behavior outcomes. Random-effects model analysis calculated standardized mean difference effect sizes...
March 15, 2017: Preventive Medicine
https://www.readbyqxmd.com/read/28306142/the-effect-of-smoking-on-inflammatory-and-bone-remodeling-markers-in-gingival-crevicular-fluid-and-subgingival-microbiota-following-periodontal-therapy
#9
D F Bunaes, M Mustafa, H G Mohamed, S A Lie, K N Leknes
BACKGROUND AND OBJECTIVE: Periodontal health is mediated by suppressing microorganisms inducing a local inflammatory host response. Smoking may impair this process. This study compares gingival crevicular fluid levels of inflammatory and bone remodeling markers in heavy smokers and non-smokers following active and supportive periodontal therapy in patients with chronic periodontitis. MATERIAL AND METHODS: Gingival crevicular fluid and subgingival plaque were collected from the deepest periodontal pocket in 50 patients, 25 smokers and 25 non-smokers, at baseline (T0), following active (T1) and 12 mo of supportive periodontal therapy (T2)...
March 17, 2017: Journal of Periodontal Research
https://www.readbyqxmd.com/read/28298995/the-all-on-four-treatment-concept-systematic-review
#10
REVIEW
David Soto-Penaloza, Regino Zaragozí-Alonso, María Penarrocha-Diago, Miguel Penarrocha-Diago
OBJECTIVES: To systematically review the literature on the "all-on-four" treatment concept regarding its indications, surgical procedures, prosthetic protocols and technical and biological complications after at least three years in function. STUDY DESIGN: The three major electronic databases were screened: MEDLINE (via PubMed), EMBASE, and the Cochrane Library of the Cochrane Collaboration (CENTRAL). In addition, electronic screening was made of the 'grey literature' using the System for Information on Grey Literature in Europe - Open Grey, covering the period from January 2005 up to and including April 2016...
March 2017: Journal of Clinical and Experimental Dentistry
https://www.readbyqxmd.com/read/28298980/biological-and-antibacterial-properties-of-a-new-silver-fiber-post-in-vitro-evaluation
#11
Claudio Poggio, Federico Trovati, Matteo Ceci, Marco Chiesa, Marco Colombo, Giampiero Pietrocola
BACKGROUND: The incorporation of nano silver particles (AgNPs) to improve antibacterial properties of dental materials has become increasingly common. The aim of the present study was to compare the antibacterial activity and cytotoxicity effects of different fiber posts: glass fiber post, quartz fiber post, nano fiber post and silver fiber post. MATERIAL AND METHODS: The antibacterial activity against S. mutans, S. salivarius and S. sanguis was evaluated by using the agar disc diffusion test (ADT)...
March 2017: Journal of Clinical and Experimental Dentistry
https://www.readbyqxmd.com/read/28298774/a-survey-on-awareness-about-the-role-of-anesthesia-and-anesthesiologists-among-the-patients-undergoing-surgeries-in-a-tertiary-care-teaching-women-and-children-hospital
#12
Vinay Marulasiddappa, H N Nethra
BACKGROUND: Although anesthesiology has grown tremendously and although anesthesiologists play a crucial role in the perioperative management of patients and also outside operating theater (OT) such as critical care, pain clinic, and labor analgesia, they do not get due recognition. We conducted a study to assess the awareness about the role of anesthesia and anesthesiologists among patients scheduled to undergo surgery in a Government Tertiary Care Teaching Women and Children Hospital...
January 2017: Anesthesia, Essays and Researches
https://www.readbyqxmd.com/read/28298244/frailty-related-to-anesthesia-guided-by-the-index-bispectral-frail-study-study-protocol-for-a-randomized-controlled-trial
#13
Morgan Le Guen, Marie Herr, Antoine Bizard, Caroline Bichon, Nathalie Boichut, Thierry Chazot, Ngai Liu, Joel Ankri, Marc Fischler
BACKGROUND: Currently, patients older than 60 years of age represent 25% of the population and are at an increased risk during surgery. Therefore, reducing postoperative morbidity and mortality is a major concern in medical research and practice. Dependence on caregivers and cognitive impairment represent two major risk factors in the elderly, especially in frail patients after surgery under general anesthesia. In this context, continuous monitoring of the depth of anesthesia using a bispectral index (BIS) sensor may reduce the occurrence of impairments by gaining better control of the anesthetic depth...
March 16, 2017: Trials
https://www.readbyqxmd.com/read/28297424/dosimetric-impact-of-cylinder-size-in-high-dose-rate-vaginal-cuff-brachytherapy-vcbt-for-primary-endometrial-cancer
#14
Hualin Zhang, Mahesh Gopalakrishnan, Plato Lee, Zhuang Kang, Vythialingam Sathiaseelan
The purpose of this study was to evaluate the dosimetric impact of cylinder size in high-dose-rate (HDR) vaginal cuff brachytherapy (VCBT). Sample plans of HDR VCBT in a list of cylinders ranging from 2.5 to 4 cm in diameter at 0.5 cm increment were created and analyzed. The doses were prescribed either at the 0.5 cm depth with 5.5 Gy for 4 fractions or at the cylinder surface with 8.8 Gy for 4 fractions, in various treatment lengths. A 0.5 cm shell volume called PTV_Eval was contoured for each plan and served as the target volume for dosimetric evaluation...
September 2016: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28295862/sample-size-of-the-reference-sample-in-a-case-augmented-study
#15
Palash Ghosh, Anup Dewanji
The case-augmented study, in which a case sample is augmented with a reference (random) sample from the source population with only covariates information known, is becoming popular in different areas of applied science such as pharmacovigilance, ecology, and econometrics. In general, the case sample is available from some source (for example, hospital database, case registry, etc.); however, the reference sample is required to be drawn from the corresponding source population. The required minimum size of the reference sample is an important issue in this regard...
March 13, 2017: Pharmacoepidemiology and Drug Safety
https://www.readbyqxmd.com/read/28295794/alcohol-and-disadvantaged-men-a-feasibility-trial-of-an-intervention-delivered-by-mobile-phone
#16
Iain K Crombie, Linda Irvine, Donald W Falconer, Brian Williams, Ian W Ricketts, Claire Jones, Gerry Humphris, John Norrie, Peter Slane, Peter Rice
INTRODUCTION AND AIMS: Disadvantaged men suffer substantial harm from heavy drinking. This feasibility study developed and evaluated the methods for a trial of a brief intervention delivered by text messages to disadvantaged men. It aimed to test the methods for recruitment and retention, to monitor engagement with the intervention and assess the overall acceptability of study methods. DESIGN AND METHODS: Disadvantaged men aged 25-44 years who had ≥2 episodes of binge drinking (≥8 units in one session) in the preceding month were recruited...
March 13, 2017: Drug and Alcohol Review
https://www.readbyqxmd.com/read/28295659/genetic-parameters-for-fur-quality-graded-on-live-animals-and-dried-pelts-of-american-mink-neovison-vison
#17
J P Thirstrup, J Jensen, M S Lund
Fur quality and skin size are integral qualities in the mink industry and are main determinants of sales price and subsequent income for mink fur producers. Parental animals of future generations are selected based on quality grading from live animals, but selection response is obtained from dried skins sold after pelting. In this study, we evaluated traits assessed during live grading and pelt traits examined on dried skins to determine correlation between live and pelt traits. Grading traits and body weight were measured during live animal grading for 9,539 Brown American mink, and pelt quality traits and skin size were evaluated on 8,385 dried mink skins after pelting...
March 10, 2017: Journal of Animal Breeding and Genetics, Zeitschrift Für Tierzüchtung und Züchtungsbiologie
https://www.readbyqxmd.com/read/28295287/design-considerations-for-identifying-breast-cancer-risk-factors-in-a-population-based-study-in-africa
#18
Louise A Brinton, Baffour Awuah, Joe Nat Clegg-Lamptey, Beatrice Wiafe-Addai, Daniel Ansong, Kofi M Nyarko, Seth Wiafe, Joel Yarney, Richard Biritwum, Michelle Brotzman, Andrew A Adjei, Ernest Adjei, Francis Aitpillah, Lawrence Edusei, Florence Dedey, Sarah J Nyante, Joseph Oppong, Ernest Osei-Bonsu, Nicholas Titiloye, Verna Vanderpuye, Emma Brew Abaidoo, Bernard Arhin, Isaac Boakye, Margaret Frempong, Naomi Ohene Oti, Victoria Okyne, Jonine D Figueroa
Although breast cancer is becoming more prevalent in Africa, few epidemiologic studies have been undertaken and appropriate methodologic approaches remain uncertain. We therefore conducted a population-based case-control study in Accra and Kumasi, Ghana, enrolling 2,202 women with lesions suspicious for breast cancer and 2,161 population controls. Biopsy tissue for cases prior to neoadjuvant therapy (if given), blood, saliva and fecal samples were sought for study subjects. Response rates, risk factor prevalences, and odds ratios (OR) for established breast cancer risk factors were calculated...
March 13, 2017: International Journal of Cancer. Journal International du Cancer
https://www.readbyqxmd.com/read/28294468/memory-impairment-and-the-mediating-role-of-task-difficulty-in-patients-with-schizophrenia
#19
REVIEW
Kyrsten M Grimes, Anosha Zanjani, Konstantine K Zakzanis, C Psych
Using meta-analytic methods, we sought to synthesize the research literature on memory impairment in schizophrenia. Additionally, we compared performances across memory measures to determine if task difficulty (e.g., effortful encoding and retrieval versus non effortful encoding and retrieval) could account for variance across studies. Our primary measures of interest included the California Verbal Learning Test, Wechsler Memory Scale, Rey Auditory Verbal Learning Test, Hopkins Verbal Learning Test, Rey Osterrieth Complex Figure Test, and the Benton Visual Retention Test...
March 14, 2017: Psychiatry and Clinical Neurosciences
https://www.readbyqxmd.com/read/28294408/tumor-necrosis-factor-%C3%AE-308g-a-and-238g-a-polymorphisms-are-associated-with-increased-risks-of-sepsis-evidence-from-an-updated-meta-analysis
#20
Mu Zhang, Yu Zhao, Qiong Liu
Previous studies have reported the relationship between tumor necrosis factor-α (TNF-α) -308G/A and -238G/A polymorphisms and sepsis risk with inconsistent results. The aim of this study was to estimate the association of the two polymorphisms with risk of sepsis or sepsis-related mortality using a meta-analysis. PubMed, Embase, and Web of Science databases were searched up to June 20 2016. Pooled odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using fixed or random effect model. Twenty-six studies were included in this meta-analysis...
March 15, 2017: APMIS: Acta Pathologica, Microbiologica, et Immunologica Scandinavica
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