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Calibration logistic regression

Joseph M Czerniecki, Aaron P Turner, Rhonda M Williams, Mary Lou Thompson, Greg Landry, Kevin Hakimi, Rebecca Speckman, Daniel C Norvell
OBJECTIVE: The objective of this study was the development of AMPREDICT-Mobility, a tool to predict the probability of independence in either basic or advanced (iBASIC or iADVANCED) mobility 1 year after dysvascular major lower extremity amputation. METHODS: Two prospective cohort studies during consecutive 4-year periods (2005-2009 and 2010-2014) were conducted at seven medical centers. Multiple demographic and biopsychosocial predictors were collected in the periamputation period among individuals undergoing their first major amputation because of complications of peripheral arterial disease or diabetes...
October 14, 2016: Journal of Vascular Surgery
Peter J Kelly, Gregory W Albers, Anastasios Chatzikonstantinou, Gian Marco De Marchis, Julia Ferrari, Paul George, Mira Katan, Michael Knoflach, Jong S Kim, Linxin Li, Eun-Jae Lee, Jean-Marc Olivot, Francisco Purroy, Nicolas Raposo, Peter M Rothwell, Vijay K Sharma, Bo Song, Georgios Tsivgoulis, Cathal Walsh, Yuming Xu, Aine Merwick
BACKGROUND: Identification of patients at highest risk of early stroke after transient ischaemic attack has been improved with imaging based scores. We aimed to compare the validity and prognostic utility of imaging-based stroke risk scores in patients after transient ischaemic attack. METHODS: We did a pooled analysis of published and unpublished individual-patient data from 16 cohort studies of transient ischaemic attack done in Asia, Europe, and the USA, with early brain and vascular imaging and follow up...
November 2016: Lancet Neurology
H Felix Fischer, Inka Wahl, Sandra Nolte, Gregor Liegl, Elmar Brähler, Bernd Löwe, Matthias Rose
To investigate differential item functioning (DIF) of PROMIS Depression items between US and German samples we compared data from the US PROMIS calibration sample (n = 780), a German general population survey (n = 2,500) and a German clinical sample (n = 621). DIF was assessed in an ordinal logistic regression framework, with 0.02 as criterion for R(2) -change and 0.096 for Raju's non-compensatory DIF. Item parameters were initially fixed to the PROMIS Depression metric; we used plausible values to account for uncertainty in depression estimates...
October 16, 2016: International Journal of Methods in Psychiatric Research
Shu-Chun Chuang, Hui-Ling Chen, Wei-Ting Tseng, I-Chien Wu, Chih-Cheng Hsu, Hsing-Yi Chang, Yii-Der Ida Chen, Marion M Lee, Kiang Liu, Chao Agnes Hsiung
BACKGROUND: A previous study indicated that 31% of the elderly in Taiwan have a vitamin D deficiency. Vitamin D adequacy has been associated with physical performance in the elderly. OBJECTIVES: The first aim of the current study was to identify the determinants for vitamin D deficiency. The second aim was to evaluate the association between vitamin D status and physical performance. DESIGN: A total of 5664 community-dwelling participants aged ≥55 y were recruited since 2008...
October 12, 2016: American Journal of Clinical Nutrition
Daniel J Rubin, Elizabeth A Handorf, Sherita Hill Golden, Deborah B Nelson, Marie E McDonnell, Huaqing Zhao
OBJECTIVE: To develop and validate a tool to predict the risk of all-cause readmission within 30 days (30-d readmission) among hospitalized patients with diabetes. METHODS: A cohort of 44,203 discharges was retrospectively selected from the electronic records of adult patients with diabetes hospitalized at an urban academic medical center. Discharges of 60% of the patients (n = 26,402) were randomly selected as a training sample to develop the index. The remaining 40% (n = 17,801) were selected as a validation sample...
October 2016: Endocrine Practice
Peter D Chang, Daniel S Chow, Peter H Yang, Christopher G Filippi, Angela Lignelli
OBJECTIVE: Recurrence of glioblastoma multiforme (GBM) arises from areas of microscopic tumor infiltration that have yet to disrupt the blood-brain barrier. We hypothesize that these microscopic foci of invasion cause subtle variations in the apparent diffusion coefficient (ADC) and FLAIR signal detectable with the use of computational big-data modeling. MATERIALS AND METHODS: Twenty-six patients with native GBM were studied immediately after undergoing gross total tumor resection...
October 11, 2016: AJR. American Journal of Roentgenology
R T Spence, E Zargaran, M Hameed, D Fong, E Shangguan, R Martinez, P Navsaria, A Nicol
BACKGROUND: The cost of Abbreviated Injury Scale (AIS) coding has limited its utility in areas of the world with the highest incidence of trauma. We hypothesised that emerging mobile health (m-health) technology could offer a cost-effective alternative to the current gold-standard AIS mechanism in a high-volume trauma centre in South Africa. METHODS: A prospectively collected sample of consecutive patients admitted following a traumatic injury that required an operation during a 1-month period was selected for the study...
September 8, 2016: South African Medical Journal, Suid-Afrikaanse Tydskrif Vir Geneeskunde
Margot M Koeneman, Freyja Hm van Lint, Sander Mj van Kuijk, Luc Jm Smits, Loes Fs Kooreman, Roy Fpm Kruitwagen, Arnold J Kruse
This study aims to develop a prediction model for spontaneous regression of cervical intraepithelial neoplasia grade 2 (CIN 2) lesions based on simple clinical and pathological parameters. The study was conducted at Maastricht University Medical Center, the Netherlands. The prediction model was developed in a retrospective cohort of 129 women with a histological diagnosis of CIN 2 who were managed by watchful waiting for 6-24months. Five potential predictors for spontaneous regression were selected based on the literature and expert opinion and were analyzed in a multivariable logistic regression model, followed by backward stepwise deletion based on the Wald test...
September 30, 2016: Human Pathology
Tommy Nyberg, Ida Hed Myrberg, Pernilla Omerov, Gunnar Steineck, Ullakarin Nyberg
BACKGROUND: Parents who lose a child by suicide have elevated risks of depression. No clinical prediction tools exist to identify which suicide-bereaved parents will be particularly vulnerable; we aimed to create a prediction model for long-term depression for this purpose. METHOD: During 2009 and 2010 we collected data using a nationwide study-specific questionnaire among parents in Sweden who had lost a child aged 15-30 by suicide in years 2004-2007. Current depression was assessed with the Patient Health Questionnaire (PHQ-9) and a single question on antidepressant use...
2016: PloS One
D Nieboer, Y Vergouwe, Danna P Ankerst, Monique J Roobol, Ewout W Steyerberg
BACKGROUND: New markers hold the promise of improving risk prediction for individual patients. We aimed to compare the performance of different strategies to extend a previously developed prediction model with a new marker. METHODS: Our motivating example was the extension of a risk calculator for prostate cancer with a new marker that was available in a relatively small dataset. Performance of the strategies was also investigated in simulations. Development, marker and test sets with different sample sizes originating from the same underlying population were generated...
September 27, 2016: BMC Medical Research Methodology
Kari Kraemer, Mark E Cohen, Yaoming Liu, Douglas C Barnhart, Shawn J Rangel, Jacqueline M Saito, Karl Y Bilimoria, Clifford Y Ko, Bruce L Hall
BACKGROUND: There is an increased desire of patients and families to be involved in the surgical decision making process. A surgeon's ability to provide patients and families with patient-specific estimates of postoperative complications is critical for shared decision making and informed consent. Surgeons can also use patient-specific risk estimates to decide whether or not to operate and what options to give to patients. Our objective was to develop and evaluate a publicly available risk estimation tool that would cover many common pediatric surgical procedures across all specialties...
August 24, 2016: Journal of the American College of Surgeons
Tan Firat Eyuboglu, Kezban Olcay, Mutlu Özcan
OBJECTIVES: This study assessed the outcome measures of single-visit root canal retreatments and frequency of periapical complications considering preoperative, intraoperative and postoperative factors. MATERIALS AND METHODS: Between November 2011 and December 2012, in 173 patients, a total of 234 endodontically treated teeth were retreated in a single appointment by one experienced endodontist. Five teeth were extracted and 119 teeth were lost to follow-up yielding to 110 teeth (47 %) to be examined by two calibrated examiners for the outcome of healing (periapical index score-PAI ≤2; no signs or symptoms) or non-healing (presence of apical periodontitis-PAI >2; signs or symptoms)...
September 22, 2016: Clinical Oral Investigations
Joonghee Kim, Kyuseok Kim, Clifton W Callaway, Kibbeum Doh, Jungho Choi, Jongdae Park, You Hwan Jo, Jae Hyuk Lee
PURPOSE: The probability of the return of spontaneous circulation (ROSC) and subsequent favourable outcomes changes dynamically during advanced cardiac life support (ACLS). We sought to model these changes using time-to-event analysis in out-of-hospital cardiac arrest (OHCA) patients. METHODS: Adult (≥18 years old), non-traumatic OHCA patients without prehospital ROSC were included. Utstein variables and initial arterial blood gas measurements were used as predictors...
September 19, 2016: Resuscitation
Gbenga A Kayode, Diederick E Grobbee, Mary Amoakoh-Coleman, Ibrahim Taiwo Adeleke, Evelyn Ansah, Joris A H de Groot, Kerstin Klipstein-Grobusch
BACKGROUND: Stillbirth is a major contributor to perinatal mortality and it is particularly common in low- and middle-income countries, where annually about three million stillbirths occur in the third trimester. This study aims to develop a prediction model for early detection of pregnancies at high risk of stillbirth. METHODS: This retrospective cohort study examined 6,573 pregnant women who delivered at Federal Medical Centre Bida, a tertiary level of healthcare in Nigeria from January 2010 to December 2013...
2016: BMC Pregnancy and Childbirth
Adam Shardlow, Natasha J McIntyre, Richard J Fluck, Christopher W McIntyre, Maarten W Taal
BACKGROUND: Chronic kidney disease (CKD) is commonly managed in primary care, but most guidelines have a secondary care perspective emphasizing the risk of end-stage kidney disease (ESKD) and need for renal replacement therapy. In this prospective cohort study, we sought to study in detail the natural history of CKD in primary care to better inform the appropriate emphasis for future guidance. METHODS AND FINDINGS: In this study, 1,741 people with CKD stage 3 were individually recruited from 32 primary care practices in Derbyshire, United Kingdom...
September 2016: PLoS Medicine
Monica Cesarini, Gary S Collins, Anders Rönnblom, Antonieta Santos, Lai Mun Wang, Daniel Sjöberg, Miles Parkes, Satish Keshav, Simon P L Travis
BACKGROUND/AIM: Acute severe colitis [ASC] is associated with major morbidity. We aimed to develop and externally validate an index that predicted ASC within 3 years of diagnosis. METHODS: The development cohort included patients aged 16-89 years, diagnosed with ulcerative colitis [UC] in Oxford and followed for 3 years. Primary outcome was hospitalization for ASC, excluding patients admitted within 1 month of diagnosis. Multivariable logistic regression examined the adjusted association of seven risk factors with ASC...
September 19, 2016: Journal of Crohn's & Colitis
L Wynants, Y Vergouwe, S Van Huffel, D Timmerman, B Van Calster
Clinical risk prediction models are increasingly being developed and validated on multicenter datasets. In this article, we present a comprehensive framework for the evaluation of the predictive performance of prediction models at the center level and the population level, considering population-averaged predictions, center-specific predictions, and predictions assuming an average random center effect. We demonstrated in a simulation study that calibration slopes do not only deviate from one because of over- or underfitting of patterns in the development dataset, but also as a result of the choice of the model (standard versus mixed effects logistic regression), the type of predictions (marginal versus conditional versus assuming an average random effect), and the level of model validation (center versus population)...
September 19, 2016: Statistical Methods in Medical Research
Peter Rijnbeek
Massive numbers of electronic health records are currently being collected globally, including structured data in the form of diagnoses, medications, laboratory test results, and unstructured data contained in clinical narratives. This opens unprecedented possibilities for research and ultimately patient care. However, actual use of these databases in a multi-center study is severely hampered by a variety of challenges, e.g., each database has a different database structure and uses different terminology systems...
September 2016: Journal of Hypertension
Hu Hei, Yongping Song, Jianwu Qin
BACKGROUND AND OBJECTIVES: Central compartment neck dissection (CCND) is recommended for patients with papillary thyroid carcinoma (PTC). However, whether to perform contralateral CCND remains unclear. An individualized estimation of the contralateral central neck metastasis (CNM) risk would assist in the tailoring of treatment for PTC patients. METHODS: Consecutive patients who underwent bilateral CCND for unilateral PTC between 2012 and 2014 in a tertiary center were identified...
September 16, 2016: Journal of Surgical Oncology
Atsushi Nakagomi, Sho Okada, Toshihiro Shoji, Yoshio Kobayashi
BACKGROUND: Several studies have reported that central systolic blood pressure (SBP) estimation is affected by calibration methods. However, whether central pulsatile indices, namely pulse pressure (PP) and fractional PP (FPP) (defined as PP/mean arterial pressure (MAP)), also depend on calibration methods remains uninvestigated. This study assessed the accuracy and discriminatory ability of these indices for coronary atherosclerosis using 2 calibration methods. METHODS: Post-hoc analysis of a previous cross-sectional study (n = 139) that investigated the association between central pulsatile indices and coronary atherosclerosis...
September 15, 2016: American Journal of Hypertension
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