Stefanie von Felten

Stefanie von Felten
University of Zurich | UZH · Department of Biostatistics

PhD

About

130
Publications
23,374
Reads
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2,293
Citations
Introduction
I am working in the Department of Biostatistics of the Epidemiology, Biostatistics and Prevention Institute at University of Zurich since October 2018. I am a member of the Research Methods Consulting team. My experience on applied statistics builds on my former research as a plant ecologist and my work as statistician at the Clinical Trial Unit/Department of Clinical Research of the University of Basel between 2010 and 2018. Beside my activities at the EBPI I am a member of oikostat GmbH, a company for statistical consulting and analysis.
Additional affiliations
October 2018 - present
University of Zurich
Position
  • Statistician
August 2010 - September 2018
Universitätsspital Basel
Position
  • Statistician
January 2009 - December 2010
Swiss Federal Institute for Forest, Snow and Landscape Research WSL

Publications

Publications (130)
Article
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To assess the incidence and severity of changes in hearing threshold in patients undergoing high-dose pencil-beam-scanning proton therapy (PBS-PT). This retrospective cohort study included fifty-one patients (median 50 years (range, 13–68)) treated with PBS-PT for skull base tumors. No chemotherapy was delivered. Pure tone averages (PTAs)were deter...
Article
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Background Family members of critically ill patients face considerable uncertainty and distress during their close others’ intensive care unit (ICU) stay. About 20–60% of family members experience adverse mental health outcomes post-ICU, such as symptoms of anxiety, depression, and posttraumatic stress. Guidelines recommend structured family inclus...
Article
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Background Rehabilitation strategies after abdominal surgery enhance recovery and improve outcome. A cornerstone of rehabilitation is respiratory physiotherapy with inspiratory muscle training to enhance pulmonary function. Pre-habilitation is the process of enhancing functional capacity before surgery in order to compensate for the stress of surge...
Article
Objectives: Portal hypertensive polyps (PHPs) are incompletely characterized lesions that can be found in the distal stomach of patients with portal hypertension. We aimed to delineate clinical factors associated with the appearance of these rare polyps. Material and methods: We conducted a cross-sectional study of a cohort with 513 cirrhotic pa...
Article
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Background: The reporting quality in medical research has recently been critically discussed. While reporting guidelines intend to maximize the value from funded research, and initiatives such as the EQUATOR network have been introduced to advance high quality reporting, the uptake of the guidelines by researchers could be improved. The aim of thi...
Article
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Background With the goal of reducing the prevalence of early childhood caries, the city of Zurich, Switzerland, started a specific prevention programme in 2010. All 2-year-olds are invited to a free dental check-up at a local public dental health service before the first legally mandated yearly dental check-up for school children between 4 and 5 ye...
Article
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Background Measures of the sonorheometry based Quantra® viscoelastic hemostatic analyzer (HemoSonics, LCC, Charlottesville, VA, USA) were compared with corresponding results of the ROTEM® sigma device (Instrumentation Laboratory, Bedford, MA, USA). Methods In thirty-eight patients scheduled for elective cardiac surgery between December 2018 and Oc...
Article
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Background Klebsiella spp. are opportunistic pathogens which can cause severe infections, are often multi-drug resistant and are a common cause of hospital-acquired infections. Multiple new Klebsiella species have recently been described, yet their clinical impact and antibiotic resistance profiles are largely unknown. We aimed to explore Klebsiell...
Article
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Background Neonatal mortality in Guinea accounts for about 30% of all fatalities in children younger than five years. Countrywide, specialized neonatal intensive care is provided in one single clinic with markedly limited resources. To implement targeted measures, prospective data on patient characteristics and factors of neonatal death are needed....
Article
Objective: Current guidelines recommending rapid revascularisation of symptomatic carotid stenosis are largely based on data from clinical trials performed at a time when best medical therapy was potentially less effective than today. The risk of stroke and its predictors among patients with symptomatic carotid stenosis awaiting revascularisation i...
Article
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Background: Direct-acting antivirals (DAA) have revolutionized the therapy of chronic hepatitis C (CHC) and have replaced previous PEG-interferon/ribavirin (PEG-IFN/RBV) treatment. Patients with CHC and advanced liver disease are at increased risk for hepatocellular carcinoma (HCC). However, the effects of DAA-based CHC treatment on subsequent HCC...
Article
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Objective Current guidelines recommending rapid revascularisation of symptomatic carotid stenosis are largely based on data from clinical trials performed at a time when best medical therapy was potentially less effective than today. The risk of stroke and its predictors among patients with symptomatic carotid stenosis awaiting revascularisation in...
Article
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Background Adverse responses to critical illness, such as symptoms of depression, anxiety or posttraumatic stress, are relatively common among family members. The role of risk factors, however, remains insufficiently understood, but may be important to target those family members most in need for support. We therefore examined the association of pa...
Article
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Background Families of critically ill persons face uncertainty and experience distress during and after their close other's stay in an intensive care unit (ICU). Proactive nurse engagement and support is recommended to meet families' needs in the ICU, but little is known about its impact on quality of family care. We introduced a family support int...
Article
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Background Quality in medical research has recently been criticized for being low, especially in observational research. Methodology is increasingly difficult, but collaboration between clinical researchers and biostatisticians may improve research and reporting quality. The aim of this study is to quantify the value of a biostatistician in the tea...
Article
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Background: Hospital acquired pneumonia (HAP) is divided in two distinct groups, ventilator-associated pneumonia (VAP) and non-ventilator-associated HAP (nvHAP). Although nvHAP occurs more frequently than VAP and results in similar mortality and costs, prevention guidelines and prevention focus almost exclusively on VAP. Scientific evidence about...
Article
Nearly half of all patients with atrial fibrillation (AF) undergoing electrical cardioversion (ECV) expe- rience AF recurrences within 6 months, even with antiarrhythmic drug treatment. 1 As inflammatory biomarkers are associated with AF recurrences, anti- inflammatory treatment may improve long-term success rates after ECV. 2 In this pilot study,...
Article
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The success of habitat enhancements is typically assessed by subsequent monitoring of the focal taxonomic group. However, enhancement actions are likely to affect other, non-targeted species. On a south-facing slope in the Swiss Jura mountains, a mixed-forest stand was thinned out by irregular removal cuttings to improve the habitat conditions for...
Article
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Introduction Delirium is frequently observed in the intensive care unit (ICU) population, in particular. Until today, there is no evidence for any reliable pharmacological intervention to treat delirium. The Basel BOMP-AID ( B etter O utcome with M elatonin compared to P lacebo A dministered to normalize sleep-wake cycle and treat hypoactive I CU D...
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Locally, plant species richness supports many ecosystem functions. Yet, the mechanisms driving these often‐positive biodiversity–ecosystem functioning relationships are not well understood. Spatial resource partitioning across vertical resource gradients is one of the main hypothesized causes for enhanced ecosystem functioning in more biodiverse gr...
Article
Background: Over the past decades, stroke risk associated with carotid disease has decreased, reflecting improvements in medical therapy and a more rigorous control of vascular risk factors. It is less clear whether the procedural risk of carotid revascularization has declined over time. Methods: We analyzed temporal changes in procedural risks...
Article
Background and Purpose—Stenting for symptomatic carotid stenosis (carotid artery stenting [CAS]) carries a higher risk of procedural stroke or death than carotid endarterectomy (CEA). It is unclear whether this extra risk is present both on the day of procedure and within 1 to 30 days thereafter and whether clinical risk factors differ between thes...
Article
Importance Therapeutic options for patients with secondary progressive multiple sclerosis (SPMS) are limited. Objective To analyze disability progression in patients with SPMS treated with rituximab compared with matched control patients never treated with rituximab. Design, Setting, and Participants This retrospective cohort study analyzed data...
Article
Background and Purpose— Stenting for symptomatic carotid stenosis (carotid artery stenting [CAS]) carries a higher risk of procedural stroke or death than carotid endarterectomy (CEA). It is unclear whether this extra risk is present both on the day of procedure and within 1 to 30 days thereafter and whether clinical risk factors differ between the...
Article
Background: Chronic hyponatremia is common and associated with increased morbidity and mortality. However whether treatment improves outcome in patients without significant symptoms is unclear. We here assessed the therapeutic outcome on clinical symptoms, neurocognitive and neuromuscular function in patients with chronic non-profound hyponatremia...
Article
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Background: There is limited evidence about the optimal length of washout when switching from natalizumab to fingolimod. Objective: To study if a washout period of 4 weeks is associated with less disease activity compared to 8 weeks. Methods: 25 patients with Relapsing Remitting Multiple Sclerosis were included in an open label, prospective st...
Article
The nervous system plays a key role in controlling the dynamic functions of multicellular complex organisms. Although peripheral nerves are supposed to play a pivotal role in tumor growth and dissemination, little experimental evidence exists to date. We assessed the effect of denervation on breast cancer growth by magnetic resonance imaging (MRI)...
Article
Aggressive behavior and violence in psychiatric patients have often been quoted to justify more restrictive settings in psychiatric facilities. However, the effects of open vs. locked door policies on aggressive incidents remain unclear. This study had a naturalistic observational design and analyzed the occurrence of aggressive behavior as well as...
Article
Background & aims: Cardiac surgery is accompanied by oxidative stress and systemic inflammatory response, which may be associated with organ dysfunction and increased mortality. Selenium and selenoenzymes are important constituents of anti-oxidative defense. We hypothesized that high-dose sodium selenite supplementation can attenuate the postopera...
Article
Full-text available
Background/objectives Delirium is a neurobehavioural disturbance that frequently develops particularly in the intensive care unit (ICU) population. It was first described more than half a century ago, where it was already discovered as a state that might come along with serious complications such as prolonged ICU and hospital stay, reduced quality...
Article
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Background Vaginal delivery, especially operative assisted vaginal delivery, seems to be a major stressor for the neonate. The objective of this study was to evaluate the stress response after metal cup versus Kiwi Omnicup® ventouse delivery. Methods The study was a secondary observational analysis of data from a former prospective randomised place...
Article
Background: Randomized controlled trials have shown the efficacy of systemic treatments in moderate-to-severe psoriasis. Clinical outcomes in psoriasis patients under real-world conditions are less well understood. Objective: This study compared Psoriasis Area and Severity Index (PASI) and Dermatological Life Quality Index (DLQI) improvement in...
Article
We are convinced that advancing the least restrictive approaches without endangering our patients and the general population is a crucial goal of psychiatry. We thank Thomas Pollmächer and Tilman Steinert for stimulating the discussion of our publication on suicide risk and absconding in hospitals without locked door policies.
Article
Aims: The British National Institute of Clinical Excellence (NICE) guidelines recommend to use DES instead of BMS only in lesions >15mm in length or in vessels < 3mm in diameter. We analysed the impact of stent length and stent diameter on ISR in the BASKET-PROVE study population and evaluated the cost-effectiveness of DES compared to BMS. Method...
Article
Full-text available
Background: Inpatient suicide and absconding of inpatients at risk of self-endangering behaviour are important challenges for all medical disciplines, particularly psychiatry. Patients at risk are often admitted to locked wards in psychiatric hospitals to prevent absconding, suicide attempts, and death by suicide. However, there is insufficient ev...
Article
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Purpose Postpartum haemorrhage (PPH) represents a leading cause of maternal morbidity and mortality. Giving oxytocin after birth reduces the risk for PPH. It has never been tested whether different methods of oxytocin administration affect the maternal outcome. This study aims to compare the infusion versus the bolus application of oxytocin after s...
Article
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Acquisition of IDH1 or IDH2 mutation (IDHmut) is among the earliest genetic events that take place in the development of most low-grade glioma (LGG). IDHmut has been associated with longer overall patient survival. However, its impact on malignant transformation (MT) remains to be defined. A collection of 210 archived adult LGG previously stratifie...
Article
Background: Cabazitaxel significantly improves overall survival (OS) in men with metastatic castration-resistant prostate cancer (mCRPC) progressing during or after docetaxel, but is associated with a higher rate of grade ≥3 neutropenia compared with docetaxel. We thus examined the relationship between cabazitaxel-induced grade ≥3 neutropenia, bas...
Chapter
Mixed effects models are used to analyze nonindependent, that is, grouped or hierarchical data. These models are called mixed effects models because they contain fixed and random effects. Fixed effects are factors with a finite (“fixed”) number of levels (e.g., sex), whereas random effects have a theoretically infinite number of levels of which we...
Chapter
This chapter introduces five hierarchical ecological models and corresponding BUGS and Stan code. First, a hierarchical multinomial model is used to study the use of different roosting site types by an owl species based on telemetry data in relation to environmental variables. Second, we analyze the breeding success of the black stork using a zero-...
Chapter
In a generalized linear model (GLM), the distribution of the data can be chosen from a variety of statistical distributions. Therefore, these models are used when the outcome variable is a count or proportions or something else that will produce nonnormally distributed residuals in a normal linear model. We introduce the binomial, the Bernoulli, an...
Chapter
We introduce a Bayesian method to assess goodness of fit and also discuss the use of the proportion of variance explained, R2, a classical measurement of goodness of fit. Posterior predictive model checking is the comparison of the simulated data from the model with the observed data. The simulated data can differ from the observed data in various...
Chapter
Generalized linear mixed models (GLMM) are the combination of generalized linear models and linear mixed models, which means that the error distribution can be different from Gaussian and that a random factor is included in the model. We discuss the binomial model used to analyze proportions or binary outcome variables, and the Poisson model used t...
Chapter
How to select a model or to base conclusions on more than one model depends on the purpose and the design of the study. In this chapter, we discuss the difference between confirmatory and predictive analyses and explain the tradeoff between bias and precision in statistical models. We present commonly used methods to rank models according to their...
Chapter
Bayesian data analysis is the process of fitting a probability model to data and drawing inferences based on posterior distributions of the model parameters or derived quantities. Bayes’ theorem provides the theoretical background and modern computer techniques, such as the R function sim, allow for the application of these processes. The posterior...
Chapter
The checklist provides a step-by-step guide through a typical data analysis. After data checking, we start with defining a model structure depending on the nature of the data-generating process. Then, the error distribution is chosen. The explanatory variables are prepared using transformations, centering, and scaling. After model fitting, goodness...
Chapter
Normal linear models (LM) are used when the outcome variable can be modeled directly with predictor variables, that is, no link function is needed, and when the resulting residuals are approximately normally distributed. These models include widely used techniques: simple linear regression for a continuous predictor, one-way ANOVA for a categorical...
Chapter
The likelihood is a relative measure of the probability of obtaining a specific data set given a model. If the likelihood of model 1 is twice as high as the likelihood of model 2, the probability of obtaining precisely this data set is twice as large for model 1 than for model 2. The likelihood function is the likelihood for a fixed data set and va...
Chapter
Markov chain Monte Carlo (MCMC) is a simulation technique that can be used to find the posterior distribution and to sample from it. Thus, it is used to fit a model and to draw samples from the joint posterior distribution of the model parameters. The different MCMC algorithms differ in their performance in relation to speed and convergence dependi...
Chapter
Statistical models serve to communicate information in data, to think about systems, to learn from data, and to make predictions and decisions. Our daily life is governed by models. This book is about linear models and extensions of these. In a linear model, the expected value of the outcome variable itself, or a transformation thereof, is a linear...
Chapter
Prior distributions, or “priors” are important parts of the model. Improper, flat, and weakly informative prior distributions are discussed. Informative or weakly informative prior distributions have computational as well as conceptual advantages over flat priors. Conjugate priors ease the calculation of posterior distributions by hand. The influen...
Chapter
The results of the data analysis are the basis for your conclusions. They contain estimates of the effects that have been studied including a measurement of uncertainty. Often, derived parameters are more meaningful than model parameters. In addition, it is helpful to present the information needed to judge the biological (or other) relevance of th...
Chapter
Model assumptions need to be checked before drawing conclusions from any model. Usually, the residuals are independent and identically distributed (iid), when the model assumptions are met. We discuss several graphical methods for assessing independence and distribution of the residuals such as the Tukey–Anscombe or the QQ plot. We further discuss...
Chapter
Spatial autocorrelation is a general property of most ecological data sets. When data are spatially autocorrelated, the value of a random variable characterizing a site can be partially predicted by the values at neighboring sites. Spatial autocorrelation can thus be described as one of the mechanisms leading to pseudoreplication. Uncertainty will...
Article
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Tissue engineering is a popular topic in peripheral nerve repair. Combining a nerve conduit with supporting adipose derived cells could offer an opportunity to prevent time consuming Schwann cell culture or the use of an autograft with its donor site morbidity and eventually improve clinical outcome. Aim of this study was to provide a broad overvie...
Article
Hintergrund: Evidenzbasierte Therapie (EBT) genießt bei Therapeuten generell einen hohen Stellenwert und Akzeptanz. Die Anwendung von EBT in der Praxis unterliegt jedoch einigen Hindernissen. Ziel: Die Studie untersuchte den Stellenwert von EBT bei den Mitarbeitern der Therapiedienste des Universitätsspitals Basel und identifizierte die wichtigsten...
Book
Full-text available
Key Features Offers Bayesian data analysis, allowing users to obtain uncertainty measurements easily for any derived parameter of interest Written in a step-by-step approach, which is accessible to non-statisticians Includes companion website containing R-code to help users conduct Bayesian data analyses on their own data Description Bayesian Da...
Article
Bayesian Data Analysis in Ecology Using Linear Models with R, BUGS, and STAN examines the Bayesian and frequentist methods of conducting data analyses. The book provides the theoretical background in an easy-to-understand approach, encouraging readers to examine the processes that generated their data. Including discussions of model selection, mode...
Article
-Biodegradable-polymer drug-eluting stents (BP-DES) were developed to be as effective as second-generation durable-polymer drug-eluting stents (DP-DES) and as safe >1 year as bare-metal stents (BMS). Thus, very late stent thrombosis (VLST) attributable to durable polymers should no longer appear. -To address these early and late aspects, 2291 patie...
Article
Background: Non-invasive monitoring of inflammatory bowel disease is an unmet clinical need as patients in clinical remission may have residual mucosal inflammation preceding clinical relapse. Aims: We aimed to assess the value of fecal calprotectin and standardized clinical activity scoring to monitor disease activity in ulcerative colitis unde...