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https://www.readbyqxmd.com/read/28334230/guided-bayesian-imputation-to-adjust-for-confounding-when-combining-heterogeneous-data-sources-in-comparative-effectiveness-research
#1
Joseph Antonelli, Corwin Zigler, Francesca Dominici
In comparative effectiveness research, we are often interested in the estimation of an average causal effect from large observational data (the main study). Often this data does not measure all the necessary confounders. In many occasions, an extensive set of additional covariates is measured for a smaller and non-representative population (the validation study). In this setting, standard approaches for missing data imputation might not be adequate due to the large number of missing covariates in the main data relative to the smaller sample size of the validation data...
March 3, 2017: Biostatistics
https://www.readbyqxmd.com/read/28330889/robust-microbiota-based-diagnostics-for-inflammatory-bowel-disease
#2
A Eck, E F J de Groot, T G J de Meij, M Welling, P H M Savelkoul, A E Budding
Strong evidence suggests that gut microbiota is altered in inflammatory bowel disease (IBD), indicating its potential role in non-invasive diagnostics. However, no clinical applications are currently used for routine patient care. The main obstacle to implementing a gut microbiota test for IBD is the lack of standardization, which leads to high inter-laboratory variations. We studied the between-hospital and between-platform batch effects and their effect on predictive accuracy for IBD.Fecal samples from 91 pediatric IBD patients and 58 healthy children were collected...
March 22, 2017: Journal of Clinical Microbiology
https://www.readbyqxmd.com/read/28329208/differentiated-hiv-rna-viral-load-monitoring-in-resource-limited-settings-an-economic-analysis
#3
Diana M Negoescu, Zhenhuan Zhang, Heiner C Bucher, Eran Bendavid
Background: Viral load (VL) monitoring for patients receiving antiretroviral therapy (ART) is recommended worldwide. However, the costs of frequent monitoring are a barrier to implementation in resource-limited settings. The extent to which personalized monitoring frequencies may be cost-effective is unknown. Methods: We created a simulation model parameterized using person-level longitudinal data to assess the benefits of flexible monitoring frequencies. Our data-driven model tracked HIV+ individuals for 10 years following ART initiation...
March 1, 2017: Clinical Infectious Diseases: An Official Publication of the Infectious Diseases Society of America
https://www.readbyqxmd.com/read/28327195/does-rating-the-operation-videos-with-a-checklist-score-improve-the-effect-of-e-learning-for-bariatric-surgical-training-study-protocol-for-a-randomized-controlled-trial
#4
Javier Rodrigo De La Garza, Karl-Friedrich Kowalewski, Mirco Friedrich, Mona Wanda Schmidt, Thomas Bruckner, Hannes Götz Kenngott, Lars Fischer, Beat-Peter Müller-Stich, Felix Nickel
BACKGROUND: Laparoscopic training has become an important part of surgical education. Laparoscopic Roux-en-Y gastric bypass (RYGB) is the most common bariatric procedure performed. Surgeons must be well trained prior to operating on a patient. Multimodality training is vital for bariatric surgery. E-learning with videos is a standard approach for training. The present study investigates whether scoring the operation videos with performance checklists improves learning effects and transfer to a simulated operation...
March 21, 2017: Trials
https://www.readbyqxmd.com/read/28326347/the-insufficiencies-of-risk-analysis-of-impending-pathological-fractures-in-patients-with-femoral-metastases-a-literature-review
#5
Emir Benca, Janina M Patsch, Winfried Mayr, Dieter H Pahr, Reinhard Windhager
PURPOSE: Pathologic fractures in patients with bone metastases are a common problem in clinical orthopaedic routine. On one hand recognition of metastatic lesions, which are at a high risk of fracture, is essential for timely prophylactic fixation, while on the other hand patients with a low risk of pathologic fractures should be spared from overtreatment. The purpose of this review is to identify all methods for fracture risk evaluation in patients with femoral metastases in the literature and to evaluate their predictive values in clinical applications...
December 2016: Bone Reports
https://www.readbyqxmd.com/read/28324963/quantitative-assessment-of-arm-tremor-in-people-with-neurological-disorders
#6
Jeonghee Kim, Claire Parnell, Thomas Wichmann, Stephen P DeWeerth
Abnormal oscillatory movement (i.e. tremor) is usually evaluated with qualitative assessment by clinicians, and quantified with subjective scoring methods. These methods are often inaccurate. We utilized a quantitative and standardized task based on the Fitts' law to assess the performance of arm movement with tremor by controlling a gyration mouse on a computer. The experiment included the center-out tapping (COT) and rectangular track navigation (RTN) tasks. We report the results of a pilot study in which we collected the performance for healthy participants in whom tremor was simulated by imposing oscillatory movements to the arm with a vibration motor...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28321608/an-evaluation-of-z-transform-algorithms-for-identifying-subject-specific-abnormalities-in-neuroimaging-data
#7
Andrew R Mayer, Andrew B Dodd, Josef M Ling, Christopher J Wertz, Nicholas A Shaff, Edward J Bedrick, Carlo Viamonte
The need for algorithms that capture subject-specific abnormalities (SSA) in neuroimaging data is increasingly recognized across many neuropsychiatric disorders. However, the effects of initial distributional properties (e.g., normal versus non-normally distributed data), sample size, and typical preprocessing steps (spatial normalization, blurring kernel and minimal cluster requirements) on SSA remain poorly understood. The current study evaluated the performance of several commonly used z-transform algorithms [leave-one-out (LOO); independent sample (IDS); Enhanced Z-score Microstructural Assessment of Pathology (EZ-MAP); distribution-corrected z-scores (DisCo-Z); and robust z-scores (ROB-Z)] for identifying SSA using simulated and diffusion tensor imaging data from healthy controls (N = 50)...
March 20, 2017: Brain Imaging and Behavior
https://www.readbyqxmd.com/read/28321524/what-are-the-true-volumes-of-sega-tumors-reliability-of-planimetric-and-popular-semi-automated-image-segmentation-methods
#8
Konrad Stawiski, Joanna Trelińska, Dobromiła Baranska, Iwona Dachowska, Katarzyna Kotulska, Sergiusz Jóźwiak, Wojciech Fendler, Wojciech Młynarski
OBJECTIVE: To evaluate the reliability of the standard planimetric methodology of volumetric analysis and three different open-source semi-automated approaches of brain tumor segmentation. MATERIALS AND METHODS: The volumes of subependymal giant cell astrocytomas (SEGA) examined by 30 MRI studies of 10 patients from a previous everolimus-related trial (EMINENTS study) were estimated using four methods: planimetric method (modified MacDonald ellipsoid method), ITK-Snap (pixel clustering, geodesic active contours, region competition methods), 3D Slicer (level-set thresholding), and NIRFast (k-means clustering, Markov random fields)...
March 20, 2017: Magma
https://www.readbyqxmd.com/read/28320654/structured-and-sparse-canonical-correlation-analysis-as-a-brain-wide-multi-modal-data-fusion-approach
#9
Ali-Reza Mohammadi-Nejad, Gholam-Ali Hossein-Zadeh, Hamid Soltanian-Zadeh
Multi-modal data fusion has recently emerged as a comprehensive neuroimaging analysis approach, which usually uses canonical correlation analysis (CCA). However, the current CCA-based fusion approaches face problems like high-dimensionality, multi-collinearity, unimodal feature selection, asymmetry, and loss of spatial information in reshaping the imaging data into vectors. This paper proposes a structured and sparse CCA (ssCCA) technique as a novel CCA method to overcome the above problems. To investigate the performance of the proposed algorithm, we have compared three data fusion techniques: standard CCA; regularized CCA; and ssCCA and evaluated their ability to detect multi-modal data associations...
March 14, 2017: IEEE Transactions on Medical Imaging
https://www.readbyqxmd.com/read/28320627/maximal-ambient-noise-levels-and-type-of-voice-material-required-for-valid-use-of-smartphones-in-clinical-voice-research
#10
Jean Lebacq, Jean Schoentgen, Giovanna Cantarella, Franz Thomas Bruss, Claudia Manfredi, Philippe DeJonckere
PURPOSE: Smartphone technology provides new opportunities for recording standardized voice samples of patients and transmitting the audio files to the voice laboratory. This drastically improves the achievement of baseline designs, used in research on efficiency of voice treatments. However, the basic requirement is the suitability of smartphones for recording and digitizing pathologic voices (mainly characterized by period perturbations and noise) without significant distortion. In a previous article, this was tested using realistic synthesized deviant voice samples (/a:/) with three precisely known levels of jitter and of noise in all combinations...
March 17, 2017: Journal of Voice: Official Journal of the Voice Foundation
https://www.readbyqxmd.com/read/28320625/low-osmolality-and-shear-stress-during-liposuction-impair-cell-viability-in-autologous-fat-grafting
#11
T Ismail, J Bürgin, A Todorov, R Osinga, N Menzi, R D Largo, M Haug, I Martin, A Scherberich, D J Schaefer
BACKGROUND: Liposuction and subsequent autologous fat grafting have become essential techniques for fat augmentation in plastic surgery. However, standard harvesting techniques that ensure the survival of adipocytes and stromal vascular fraction (SVF) cells and thus preserve the transplanted fat volume are lacking. In particular, the effect of different parameters of the tumescent solution has not been studied in this context. We hypothesized that the osmolality of the tumescent solution could have a significant effect on the survival of adipocytes and SVF cells...
February 17, 2017: Journal of Plastic, Reconstructive & Aesthetic Surgery: JPRAS
https://www.readbyqxmd.com/read/28320462/varying-the-item-format-improved-the-range-of-measurement-in-patient-reported-outcome-measures-assessing-physical-function
#12
Gregor Liegl, Barbara Gandek, H Felix Fischer, Jakob B Bjorner, John E Ware, Matthias Rose, James F Fries, Sandra Nolte
BACKGROUND: Physical function (PF) is a core patient-reported outcome domain in clinical trials in rheumatic diseases. Frequently used PF measures have ceiling effects, leading to large sample size requirements and low sensitivity to change. In most of these instruments, the response category that indicates the highest PF level is the statement that one is able to perform a given physical activity without any limitations or difficulty. This study investigates whether using an item format with an extended response scale, allowing respondents to state that the performance of an activity is easy or very easy, increases the range of precise measurement of self-reported PF...
March 21, 2017: Arthritis Research & Therapy
https://www.readbyqxmd.com/read/28319164/modeling-the-potential-impact-on-the-us-blood-supply-of-transfusing-critically-ill-patients-with-fresher-stored-red-blood-cells
#13
Arianna Simonetti, Hussein Ezzeldin, Mikhail Menis, Stephen McKean, Hector Izurieta, Steven A Anderson, Richard A Forshee
BACKGROUND: Although some studies have suggested that transfusion recipients may have better medical outcomes if transfused with red blood cell units stored for a short time, the overall body of evidence shows mixed results. It is important to understand how using fresher stored red blood cell units for certain patient groups may affect blood availability. METHODS: Based on the Stock-and-Flow simulation model of the US blood supply developed by Simonetti et al. 2014, we evaluated a newly implemented allocation method of preferentially transfusing fresher stored red blood cell units to a subset of high-risk group of critically ill patients and its potential impact on supply...
2017: PloS One
https://www.readbyqxmd.com/read/28302428/comparison-of-intraoperative-fluoroscopic-dunn-view-with-magnetic-resonance-imaging-to-determine-femoral-version
#14
Cara Beth Lee, Hillard T Spencer
PURPOSE: To compare femoral version measured with a fluoroscopic Dunn view taken at the time of hip arthroscopy with values derived from axial magnetic resonance imaging (MRI) scans. METHODS: Of 159 hip arthroscopies performed from January 2014 through March 2015, 50 patients had magnetic resonance imaging (MRI) scans with a protocol that incorporates femoral version analysis. Dunn views are performed as a routine part of the preoperative fluoroscopic examination at the time of arthroscopy...
March 13, 2017: Arthroscopy: the Journal of Arthroscopic & related Surgery
https://www.readbyqxmd.com/read/28301392/combined-electric-and-acoustic-stimulation-with-hearing-preservation-effect-of-cochlear-implant-low-frequency-cutoff-on-speech-understanding-and-perceived-listening-difficulty
#15
René H Gifford, Timothy J Davis, Linsey W Sunderhaus, Christine Menapace, Barbara Buck, Jillian Crosson, Lori O'Neill, Anne Beiter, Phil Segel
OBJECTIVE: The primary objective of this study was to assess the effect of electric and acoustic overlap for speech understanding in typical listening conditions using semidiffuse noise. DESIGN: This study used a within-subjects, repeated measures design including 11 experienced adult implant recipients (13 ears) with functional residual hearing in the implanted and nonimplanted ear. The aided acoustic bandwidth was fixed and the low-frequency cutoff for the cochlear implant (CI) was varied systematically...
March 15, 2017: Ear and Hearing
https://www.readbyqxmd.com/read/28297426/mri-geometric-distortion-impact-on-tangential-whole-breast-imrt
#16
Amy Walker, Peter Metcalfe, Gary Liney, Vikneswary Batumalai, Kylie Dundas, Carri Glide-Hurst, Geoff P Delaney, Miriam Boxer, Mei Ling Yap, Jason Dowling, David Rivest-Henault, Elise Pogson, Lois Holloway
The purpose of this study was to determine the impact of magnetic resonance imaging (MRI) geometric distortions when using MRI for target delineation and planning for whole-breast, intensity-modulated radiotherapy (IMRT). Residual system distortions and combined systematic and patient-induced distortions are considered. This retrospective study investigated 18 patients who underwent whole-breast external beam radiotherapy, where both CT and MRIs were acquired for treatment planning. Distortion phantoms were imaged on two MRI systems, dedicated to radiotherapy planning (a wide, closed-bore 3T and an open-bore 1T)...
September 2016: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28297354/quantitative-evaluation-of-patient-setup-uncertainty-of-stereotactic-radiotherapy-with-the-frameless-6d-exactrac-system-using-statistical-modeling
#17
Vance Keeling, Sabbir Hossain, Hosang Jin, Ozer Algan, Salahuddin Ahmad, Imad Ali
The purpose of this study is to evaluate patient setup accuracy and quantify individual and cumulative positioning uncertainties associated with different hardware and software components of the stereotactic radiotherapy (SRS/SRT) with the frameless 6D ExacTrac system. A statistical model is used to evaluate positioning uncertainties of the different components of SRS/SRT treatment with the Brainlab 6D ExacTrac system using the positioning shifts of 35 patients having cranial lesions. All these patients are immobilized with rigid head-and-neck masks, simulated with Brainlab localizer and planned with iPlan treatment planning system...
May 2016: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28297280/an-innovative-method-to-acquire-the-location-of-point-a-for-cervical-cancer-treatment-by-hdr-brachytherapy
#18
Liyun Chang, Sheng-Yow Ho, Shyh-An Yeh, Tsair-Fwu Lee, Pang-Yu Chen
Brachytherapy of local cervical cancer is generally accomplished through film-based treatment planning with the prescription directed to point A, which is invisible on images and is located at a high-dose gradient area. Through a standard reconstruction method by digitizing film points, the location error for point A would be 3 mm with a condition of 30° curvature tandem, which is 10° away from the gantry rotation axis of a simulator, and has an 8.7 cm interval between the flange and the isocenter. To reduce the location error of the reconstructed point A, this paper proposes a method and demonstrates its accuracy...
November 2016: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28296319/validation-of-the-calypso-surface-beacon-transponder
#19
Maxwell Belanger, Ziad Saleh, Tom Volpe, Rich Margiasso, Xiang Li, Maria Chan, Xiaofeng Zhu, Xiaoli Tang
Calypso L-shaped Surface Beacon transponder has recently become available for clinical applications. We herein conduct studies to validate the Surface Beacon transponder in terms of stability, reproducibility, orientation sensitivity, cycle rate dependence, and respiratory waveform tracking accuracy. The Surface Beacon was placed on a Quasar respiratory phantom and positioned at the isocenter with its two arms aligned with the lasers. Breathing waveforms were simulated, and the motion of the transponder was tracked...
July 2016: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28296300/experimental-validation-of-a-kv-source-model-and-dose-computation-method-for-cbct-imaging-in-an-anthropomorphic-phantom
#20
Yannick Poirier, Mauro Tambasco
We present an experimental validation of a kilovoltage (kV) X-ray source characterization model in an anthropomorphic phantom to estimate patient-specific absorbed dose from kV cone-beam computed tomography (CBCT) imaging procedures and compare these doses to nominal weighted CT-dose index (CTDIw) dose estimates. We simulated the default Varian on-board imager 1.4 (OBI) default CBCT imaging protocols (i.e., standard-dose head, low-dose thorax, pelvis, and pelvis spotlight) using our previously developed and easy to implement X-ray point-source model and source characterization approach...
July 2016: Journal of Applied Clinical Medical Physics
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