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Missing at random

Daniel O Scharfstein, Aidan McDermott
Randomized trials with patient-reported outcomes are commonly plagued by missing data. The analysis of such trials relies on untestable assumptions about the missing data mechanism. To address this issue, it has been recommended that the sensitivity of the trial results to assumptions should be a mandatory reporting requirement. In this paper, we discuss a recently developed methodology (Scharfstein et al., Biometrics, 2018) for conducting sensitivity analysis of randomized trials in which outcomes are scheduled to be measured at fixed points in time after randomization and some subjects prematurely withdraw from study participation...
January 1, 2018: Statistical Methods in Medical Research
Guogen Shan, Hua Zhang, Tao Jiang
To compare a new binary diagnostic test with the gold standard, sensitivity and specificity are the two common measurements used to evaluate the new test. When not all the patients are verified by the gold standard due to time, budget, or cost considerations, several approaches have been proposed to compute sample size for such studies under the assumption of missing completely at random. However, the majority of them are based on asymptotic approaches that generally do not guarantee the type I and II error rates, and the remaining approaches use exact binomial distributions in sample size calculation but only the verified samples are used...
March 19, 2018: Journal of Biopharmaceutical Statistics
Kelly Lien, Alvin Chin, Anton Helman, Teresa M Chan
Introduction Podcasts and blog posts have gained popularity in Free Open Access Medical education (FOAM). Previous work suggests that podcasts may be useful for knowledge acquisition in undergraduate medical education. However, there remains a paucity of research comparing the two mediums. This study aims to investigate if there are differences in knowledge acquisition and usage conditions by medical students using podcasts and blog posts. Methods Medical students were randomized to either the podcast or blog post group...
January 15, 2018: Curēus
Carolien Zwiers, Mirjam Ea Scheffer-Rath, Enrico Lopriore, Masja de Haas, Helen G Liley
BACKGROUND: Exchange transfusion and phototherapy have traditionally been used to treat jaundice and avoid the associated neurological complications. Because of the risks and burdens of exchange transfusion, intravenous immunoglobulin (IVIg) has been suggested as an alternative therapy for alloimmune hemolytic disease of the newborn (HDN) to reduce the need for exchange transfusion. OBJECTIVES: To assess the effect and complications of IVIg in newborn infants with alloimmune HDN on the need for and number of exchange transfusions...
March 18, 2018: Cochrane Database of Systematic Reviews
Jeremy Gingrich, Yong Pu, Jennifer Roberts, Rajendiran Karthikraj, Kurunthachalam Kannan, Richard Ehrhardt, Almudena Veiga-Lopez
Exposure to bisphenolic chemicals during pregnancy occurs in > 90% of pregnancies. Bisphenolic compounds can cross the placental barrier reaching fetal circulation. However, the effects of emerging bisphenolic compounds, such as bisphenol S (BPS), on placental function remain untested. The aim was to determine if bisphenol A (BPA) or BPS, at an environmentally relevant dose, impairs placental function. Pregnant sheep were randomly distributed into three treatment groups (n = 7-8/group): control, BPA, and BPS...
March 17, 2018: Archives of Toxicology
Valirie Ndip Agbor, Noah Fongwen Takah, Leopold Ndemnge Aminde
INTRODUCTION: Hypertension is the leading cardiovascular risk factor globally, associated with a high morbidity and mortality. The high prevalence of hypertension in sub-Saharan Africa (SSA) is associated with contrastingly low awareness, treatment and control rates. Adherence to medication remains a major determinant of optimal blood pressure control. This systematic review aims to determine the prevalence, and factors associated with adherence to antihypertensive pharmacotherapy among patients with hypertension in SSA...
March 16, 2018: BMJ Open
Mamadou Alpha Diallo, Khadim Diongue, Mame Cheikh Seck, Mouhamadou Ndiaye, Ibrahima Diallo, Younouss Diedhiou, Tolla Ndiaye, Yaye Die Ndiaye, Aida Sadikh Badiane, Daouda Ndiaye
BACKGROUND: In developing countries, malaria diagnosis relies on microscopy and rapid diagnostic tests. In Senegal, national malaria control program (NMCP) regularly conducts supervisory visits in health services where malaria microscopy is performed. In this study, expert microscopists assessed the performance of laboratory technicians in malaria microscopy. METHODS: The present external quality assessment (EQA) was conducted in three different areas of malaria transmission...
March 15, 2018: Annals of Clinical Microbiology and Antimicrobials
Juliana Serje, Melanie Y Bertram, Callum Brindley, Jeremy A Lauer
Background: Human resources are consistently cited as a leading contributor to health care costs; however the availability of internationally comparable data on health worker earnings for all countries is a challenge for estimating the costs of health care services. This paper describes an econometric model using cross sectional earnings data from the International Labour Organization (ILO) that the World Health Organizations (WHO)-Choosing Interventions that are Cost-effective programme (CHOICE) has used to prepare estimates of health worker earnings (in 2010 USD) for all WHO member states...
2018: Cost Effectiveness and Resource Allocation: C/E
Silvia Paggi, Giuseppe Mogavero, Arnaldo Amato, Emanuele Rondonotti, Alida Andrealli, Gianni Imperiali, Nicoletta Lenoci, Giovanna Mandelli, Natalia Terreni, Francesco Simone Conforti, Dario Conte, Giancarlo Spinzi, Franco Radaelli
BACKGROUND:  Linked color imaging (LCI) is a newly developed image-enhancing endoscopy technology that provides bright endoscopic images and increases color contrast. We investigated whether LCI improves the detection of neoplastic lesions in the right colon when compared with high definition white-light imaging (WLI). METHODS:  Consecutive patients undergoing colonoscopy were randomized (1:1) after cecal intubation into right colon inspection at first pass by LCI or by WLI...
March 14, 2018: Endoscopy
Graciela Muniz-Terrera, Fernando Massa, Tatiana Benaglia, Boo Johansson, Andrea Piccinin, Annie Robitaille
OBJECTIVES: To model trajectories of visuospatial reasoning measured using Kohs Block Design test under realistic missing data assumptions and evaluate their association with hazard of death. METHODS: A joint longitudinal-survival model was used to estimate trajectories of visuospatial reasoning under a missing not at random assumption of participants from the Origins of Variance in the Old-Old: Octogenarian Twins study. Sensitivity analyses to missing data assumptions were conducted...
March 1, 2018: Journal of Aging and Health
Nicholas G Larkins, Jonathan C Craig, Armando Teixeira-Pinto
Missing data is an important and common source of bias in clinical research. Readers should be alert to and consider the impact of missing data when reading studies. Beyond preventing missing data in the first place, through good study design and conduct, there are different strategies available to handle data containing missing observations. Complete case analysis is often biased unless data are missing completely at random. Better methods of handling missing data include multiple imputation and models using likelihood-based estimation...
March 13, 2018: Pediatric Nephrology: Journal of the International Pediatric Nephrology Association
Jeehoon Kang, Jung-Kyu Han, Youngkeun Ahn, Shung Chull Chae, Young Jo Kim, In-Ho Chae, Seung-Ho Hur, In-Whan Seong, Jei-Keon Chae, Myeong Chan Cho, Ki-Bae Seung, Myung Ho Jeong, Han-Mo Yang, Kyung Woo Park, Hyun-Jae Kang, Bon-Kwon Koo, Hyo-Soo Kim
Third-generation P2Y12 inhibitors (prasugrel, ticagrelor) are recommended in acute myocardial infarction (AMI). We aimed to evaluate the efficacy and safety of third-generation P2Y12 inhibitors in East Asian AMI patients. From the Korean AMI Registry, 9,355 patients who received dual antiplatelet agent (aspirin with clopidogrel [AC], 6,444 [70.5%] patients; aspirin with prasugrel [AP], 1,100 [11.8%] patients; or aspirin with ticagrelor [AT], 1,811 [19.4%] patients) were analysed. In-hospital endpoints were all-cause mortality or bleeding events during admission and 1-year endpoints were major adverse cardiac and cerebrovascular events (MACCE) and major bleeding events...
March 2018: Thrombosis and Haemostasis
Thomas Uray, Andrew Lamade, Jonathan Elmer, Tomas Drabek, Jason P Stezoski, Amalea Missé, Keri Janesko-Feldman, Robert H Garman, Niel Chen, Patrick M Kochanek, Cameron Dezfulian
OBJECTIVES: Cardiac arrest etiology may be an important source of between-patient heterogeneity, but the impact of etiology on organ injury is unknown. We tested the hypothesis that asphyxial cardiac arrest results in greater neurologic injury than cardiac etiology cardiac arrest (ventricular fibrillation cardiac arrest), whereas ventricular fibrillation cardiac arrest results in greater cardiovascular dysfunction after return of spontaneous circulation. DESIGN: Prospective observational human and randomized animal study...
March 10, 2018: Critical Care Medicine
Ke-Hai Yuan, Mortaza Jamshidian, Yutaka Kano
Unless data are missing completely at random (MCAR), proper methodology is crucial for the analysis of incomplete data. Consequently, methods for effectively testing the MCAR mechanism become important, and procedures were developed via testing the homogeneity of means and variances-covariances across the observed patterns (e.g., Kim & Bentler in Psychometrika 67:609-624, 2002; Little in J Am Stat Assoc 83:1198-1202, 1988). The current article shows that the population counterparts of the sample means and covariances of a given pattern of the observed data depend on the underlying structure that generates the data, and the normal-distribution-based maximum likelihood estimates for different patterns of the observed sample can converge to the same values even when data are missing at random or missing not at random, although the values may not equal those of the underlying population distribution...
March 12, 2018: Psychometrika
Jorge Osma, Carlos Suso-Ribera, Azucena García-Palacios, Elena Crespo-Delgado, Cristina Robert-Flor, Ana Sánchez-Guerrero, Vanesa Ferreres-Galan, Luisa Pérez-Ayerra, Amparo Malea-Fernández, Mª Ángeles Torres-Alfosea
BACKGROUND: Emotional disorders, which include both anxiety and depressive disorders, are the most prevalent psychological disorders according to recent epidemiological studies. Consequently, public costs associated with their treatment have become a matter of concern for public health systems, which face long waiting lists. Because of their high prevalence in the population, finding an effective treatment for emotional disorders has become a key goal of today's clinical psychology. The Unified Protocol for the Transdiagnostic Treatment of Emotional Disorders might serve the aforementioned purpose, as it can be applied to a variety of disorders simultaneously and it can be easily performed in a group format...
March 12, 2018: Health and Quality of Life Outcomes
Brett K J Kilb, Andrew P Kurmis, Michael Parry, Karen Sherwood, Paul Keown, Bassam A Masri, Clive P Duncan, Donald S Garbuz
BACKGROUND: Once touted as the future of hip arthroplasty, metal-on-metal (MoM) bearing surfaces have fallen sharply from favor with the emergence of a strong body of evidence demonstrating unacceptably high premature implant failure rates. The previously unpredictable development of adverse local tissue reactions (ALTRs) has been a substantive contributor to this. Although the underlying pathophysiology of these so-called "pseudotumors" is now well understood, the fundamental predisposing patient risk factors have remained elusive...
February 2018: Clinical Orthopaedics and related Research
Miguel Marino, Marcello Pagano
Background: Nationally-representative surveys suggest that females have a higher prevalence of HIV than males in most African countries. Unfortunately, these results are made on the basis of surveys with non-ignorable missing data. This study evaluates the impact that differential survey nonresponse rates between males and females can have on the point estimate of the HIV prevalence ratio of these two classifiers. Methods: We study 29 Demographic and Health Surveys (DHS) from 2001 to 2010...
2018: Emerging Themes in Epidemiology
Tess Harris, Sally M Kerry, Elizabeth S Limb, Cheryl Furness, Charlotte Wahlich, Christina R Victor, Steve Iliffe, Peter H Whincup, Michael Ussher, Ulf Ekelund, Julia Fox-Rushby, Judith Ibison, Stephen DeWilde, Cathy McKay, Derek G Cook
BACKGROUND: Physical inactivity is an important cause of noncommunicable diseases. Interventions can increase short-term physical activity (PA), but health benefits require maintenance. Few interventions have evaluated PA objectively beyond 12 months. We followed up two pedometer interventions with positive 12-month effects to examine objective PA levels at 3-4 years. METHODS AND FINDINGS: Long-term follow-up of two completed trials: Pedometer And Consultation Evaluation-UP (PACE-UP) 3-arm (postal, nurse support, control) at 3 years and Pedometer Accelerometer Consultation Evaluation-Lift (PACE-Lift) 2-arm (nurse support, control) at 4 years post-baseline...
March 2018: PLoS Medicine
Michael P Meyer, Elizabeth Nevill, Maisie M Wong
BACKGROUND: Placental transfusion (by means of delayed cord clamping (DCC), cord milking, or cord stripping) confers benefits for preterm infants. It is not known if providing respiratory support to preterm infants before cord clamping improves outcomes. OBJECTIVES: To assess the efficacy and safety of respiratory support provided during DCC compared with no respiratory support during placental transfusion (in the form of DCC, milking, or stripping) in preterm infants immediately after delivery...
March 8, 2018: Cochrane Database of Systematic Reviews
Jeanette R Little, Holly H Pavliscsak, Mabel R Cooper, Lois A Goldstein, Stephanie J Fonda
Introduction: Research has shown that mobile phones can help with management of numerous health problems. As an adjunct to care management provided to injured service members rehabilitating in their communities, particularly those with mild traumatic brain injury (mTBI), post-traumatic stress (PTS), and/or behavioral health problems, the Army developed a mobile phone application called "mCare." This study examined whether service members who received mCare had higher well-being, were more satisfied with their care, and viewed mCare as a valuable part of their care management as compared with their counterparts who received standard care management alone, and whether those with mTBI, PTS, and/or behavioral health problems benefited differently from mCare...
March 1, 2018: Military Medicine
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