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Vinke PC, Combalia M, de Bock GH, Leyrat C, Spanjaart AM, Dalle S, Gomes da Silva M, Fouda Essongue A, Rabier A, Pannard M, Jalali MS, Elgammal A, Papazoglou M, Hacid MS, Rioufol C, Kersten MJ, van Oijen MG, Suazo-Zepeda E, Malhotra A, Coquery E, Anota A, Preau M, Fauvernier M, Coz E, Puig S, Maucort-Boulch D. Monitoring multidimensional aspects of quality of life after cancer immunotherapy: protocol for the international multicentre, observational QUALITOP cohort study. BMJ Open 2023; 13:e069090. [PMID: 37105689 PMCID: PMC10151860 DOI: 10.1136/bmjopen-2022-069090] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 04/29/2023] Open
Abstract
INTRODUCTION Immunotherapies, such as immune checkpoint inhibitors and chimeric antigen receptor T-cell therapy, have significantly improved the clinical outcomes of various malignancies. However, they also cause immune-related adverse events (irAEs) that can be challenging to predict, prevent and treat. Although they likely interact with health-related quality of life (HRQoL), most existing evidence on this topic has come from clinical trials with eligibility criteria that may not accurately reflect real-world settings. The QUALITOP project will study HRQoL in relation to irAEs and its determinants in a real-world study of patients treated with immunotherapy. METHODS AND ANALYSIS This international, observational, multicentre study takes place in France, the Netherlands, Portugal and Spain. We aim to include about 1800 adult patients with cancer treated with immunotherapy in a specifically recruited prospective cohort, and to additionally obtain data from historical real-world databases (ie, databiobanks) and medical administrative registries (ie, national cancer registries) in which relevant data regarding other adult patients with cancer treated with immunotherapy has already been stored. In the prospective cohort, clinical health status, HRQoL and psychosocial well-being will be monitored until 18 months after treatment initiation through questionnaires (at baseline and 3, 6, 12 and 18 months thereafter), and by data extraction from electronic patient files. Using advanced statistical methods, including causal inference methods, artificial intelligence algorithms and simulation modelling, we will use data from the QUALITOP cohort to improve the understanding of the complex relationships among treatment regimens, patient characteristics, irAEs and HRQoL. ETHICS AND DISSEMINATION All aspects of the QUALITOP project will be conducted in accordance with the Declaration of Helsinki and with ethical approval from a suitable local ethics committee, and all patients will provide signed informed consent. In addition to standard dissemination efforts in the scientific literature, the data and outcomes will contribute to a smart digital platform and medical data lake. These will (1) help increase knowledge about the impact of immunotherapy, (2) facilitate improved interactions between patients, clinicians and the general population and (3) contribute to personalised medicine. TRIAL REGISTRATION NUMBER NCT05626764.
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Affiliation(s)
- Petra C Vinke
- Epidemiology, University Medical Centre Groningen, University of Groningen, Groningen, The Netherlands
| | - Marc Combalia
- Institut d'Investigacions Biomediques August Pi i Sunyer, Barcelona, Spain
- Dermatology, Hospital Clinic of Barcelona, University of Barcelona, Barcelona, Spain
| | - Geertruida H de Bock
- Epidemiology, University Medical Centre Groningen, University of Groningen, Groningen, The Netherlands
| | - Clémence Leyrat
- Medical Statistics, London School of Hygiene and Tropical Medicine, London, UK
| | - Anne Mea Spanjaart
- Hematology, Amsterdam University Medical Centres, Amsterdam, The Netherlands
- Cancer Center Amsterdam, Amsterdam, The Netherlands
- LYMMCARE, Amsterdam, The Netherlands
| | - Stephane Dalle
- Dermatology, Cancer Research Center of Lyon, Lyon Sud Hospital, Pierre-Bénite, France
- University Claude Bernard Lyon 1, Villeurbanne, France
- ImmuCare, Cancer Institute of the Hospices Civils de Lyon, Lyon, France
| | | | | | - Aurélie Rabier
- ImmuCare, Cancer Institute of the Hospices Civils de Lyon, Lyon, France
| | - Myriam Pannard
- INSERM Unit U1296 Radiation: Defence, Health, Environment, Lumière University Lyon 2 Psychology Institute, Bron, France
| | - Mohammad S Jalali
- MGH Institute for Technology Assessment, Harvard Medical School, Boston, Massachusetts, USA
| | - Amal Elgammal
- Scientific Academy for Service Technology e.V. (ServTech), Potsdam, Germany
- Egypt University of Informatics, Cairo, Egypt
| | - Mike Papazoglou
- Scientific Academy for Service Technology e.V. (ServTech), Potsdam, Germany
- School of Computer Science and Engineering, University of New South Wales, Sydney, New South Wales, Australia
- School of Computing, Macquarie University, Sydney, New South Wales, Australia
| | - Mohand-Said Hacid
- LIRIS, CNRS UMR 5205, Universite Claude Bernard Lyon 1, Villeurbanne, France
| | - Catherine Rioufol
- Clinical Oncology Pharmacy Department, Hospital Lyon-South, Cancer Institute of the Hospices Civils de Lyon, Pierre-Benite, France
| | - Marie-José Kersten
- Hematology, Amsterdam University Medical Centres, Amsterdam, The Netherlands
- Cancer Center Amsterdam, Amsterdam, The Netherlands
- LYMMCARE, Amsterdam, The Netherlands
| | - Martijn Gh van Oijen
- Medical Oncology, Cancer Center Amsterdam, Amsterdam University Medical Centres, University of Amsterdam, Amsterdam, The Netherlands
| | - Erick Suazo-Zepeda
- Epidemiology, University Medical Centre Groningen, University of Groningen, Groningen, The Netherlands
| | - Ananya Malhotra
- Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, London, UK
| | - Emmanuel Coquery
- LIRIS, CNRS UMR 5205, Universite Claude Bernard Lyon 1, Villeurbanne, France
| | - Amélie Anota
- Direction of Clinical Research and Innovation & Human and Social Sciences, Centre Léon Bérard, Lyon, France
- French National platform Quality of Life and Cancer, Lyon, France
| | - Marie Preau
- INSERM Unit U1296 Radiation: Defence, Health, Environment, Lumière University Lyon 2 Psychology Institute, Bron, France
| | - Mathieu Fauvernier
- University Claude Bernard Lyon 1, Villeurbanne, France
- Service de Biostatistique et Bioinformatique, Hospices Civils de Lyon, Pôle Santé Publique, Lyon, France
- UMR 5558, Laboratoire de Biométrie et Biologie Évolutive, Équipe Biostatistique-Santé, CNRS, Villeurbanne, France
| | - Elsa Coz
- University Claude Bernard Lyon 1, Villeurbanne, France
- Service de Biostatistique et Bioinformatique, Hospices Civils de Lyon, Pôle Santé Publique, Lyon, France
- UMR 5558, Laboratoire de Biométrie et Biologie Évolutive, Équipe Biostatistique-Santé, CNRS, Villeurbanne, France
| | - Susana Puig
- Institut d'Investigacions Biomediques August Pi i Sunyer, Barcelona, Spain
- Dermatology, Hospital Clinic of Barcelona, University of Barcelona, Barcelona, Spain
- Instituto de Salud Carlos III, Centro de Investigación Biomédica en Red de Enfermedades Raras, Barcelona, Spain
| | - Delphine Maucort-Boulch
- University Claude Bernard Lyon 1, Villeurbanne, France
- Service de Biostatistique et Bioinformatique, Hospices Civils de Lyon, Pôle Santé Publique, Lyon, France
- UMR 5558, Laboratoire de Biométrie et Biologie Évolutive, Équipe Biostatistique-Santé, CNRS, Villeurbanne, France
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Klinkhammer H, Staerk C, Maj C, Krawitz PM, Mayr A. A statistical boosting framework for polygenic risk scores based on large-scale genotype data. Front Genet 2023; 13:1076440. [PMID: 36704342 PMCID: PMC9871367 DOI: 10.3389/fgene.2022.1076440] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Accepted: 12/20/2022] [Indexed: 01/12/2023] Open
Abstract
Polygenic risk scores (PRS) evaluate the individual genetic liability to a certain trait and are expected to play an increasingly important role in clinical risk stratification. Most often, PRS are estimated based on summary statistics of univariate effects derived from genome-wide association studies. To improve the predictive performance of PRS, it is desirable to fit multivariable models directly on the genetic data. Due to the large and high-dimensional data, a direct application of existing methods is often not feasible and new efficient algorithms are required to overcome the computational burden regarding efficiency and memory demands. We develop an adapted component-wise L 2-boosting algorithm to fit genotype data from large cohort studies to continuous outcomes using linear base-learners for the genetic variants. Similar to the snpnet approach implementing lasso regression, the proposed snpboost approach iteratively works on smaller batches of variants. By restricting the set of possible base-learners in each boosting step to variants most correlated with the residuals from previous iterations, the computational efficiency can be substantially increased without losing prediction accuracy. Furthermore, for large-scale data based on various traits from the UK Biobank we show that our method yields competitive prediction accuracy and computational efficiency compared to the snpnet approach and further commonly used methods. Due to the modular structure of boosting, our framework can be further extended to construct PRS for different outcome data and effect types-we illustrate this for the prediction of binary traits.
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Affiliation(s)
- Hannah Klinkhammer
- Institute for Medical Biometry, Informatics and Epidemiology, Medical Faculty, University of Bonn, Bonn, Germany
- Institute for Genomic Statistics and Bioinformatics, Medical Faculty, University of Bonn, Bonn, Germany
| | - Christian Staerk
- Institute for Medical Biometry, Informatics and Epidemiology, Medical Faculty, University of Bonn, Bonn, Germany
| | - Carlo Maj
- Institute for Genomic Statistics and Bioinformatics, Medical Faculty, University of Bonn, Bonn, Germany
- Center for Human Genetics, University of Marburg, Marburg, Germany
| | - Peter Michael Krawitz
- Institute for Genomic Statistics and Bioinformatics, Medical Faculty, University of Bonn, Bonn, Germany
| | - Andreas Mayr
- Institute for Medical Biometry, Informatics and Epidemiology, Medical Faculty, University of Bonn, Bonn, Germany
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3
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Marmolejo‐Ramos F, Tejo M, Brabec M, Kuzilek J, Joksimovic S, Kovanovic V, González J, Kneib T, Bühlmann P, Kook L, Briseño‐Sánchez G, Ospina R. Distributional regression modeling via generalized additive models for location, scale, and shape: An overview through a data set from learning analytics. WILEY INTERDISCIPLINARY REVIEWS. DATA MINING AND KNOWLEDGE DISCOVERY 2023; 13:e1479. [PMID: 37502671 PMCID: PMC10369920 DOI: 10.1002/widm.1479] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Revised: 06/11/2022] [Accepted: 10/05/2022] [Indexed: 07/29/2023]
Abstract
The advent of technological developments is allowing to gather large amounts of data in several research fields. Learning analytics (LA)/educational data mining has access to big observational unstructured data captured from educational settings and relies mostly on unsupervised machine learning (ML) algorithms to make sense of such type of data. Generalized additive models for location, scale, and shape (GAMLSS) are a supervised statistical learning framework that allows modeling all the parameters of the distribution of the response variable with respect to the explanatory variables. This article overviews the power and flexibility of GAMLSS in relation to some ML techniques. Also, GAMLSS' capability to be tailored toward causality via causal regularization is briefly commented. This overview is illustrated via a data set from the field of LA. This article is categorized under:Application Areas > Education and LearningAlgorithmic Development > StatisticsTechnologies > Machine Learning.
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Affiliation(s)
| | - Mauricio Tejo
- Instituto de EstadísticaUniversidad de ValparaísoValparaísoChile
| | - Marek Brabec
- Department of Statistical ModellingInstitute of Computer Science of the Czech Academy of SciencesPragueCzech Republic
| | - Jakub Kuzilek
- Czech Institute of InformaticsRobotics and Cybernetics, CTUPragueCzech Republic
- Computer Science Education/Computer Science and Society Research GroupHumboldt University of BerlinBerlinGermany
| | - Srecko Joksimovic
- Centre for Change and Complexity in LearningUniversity of South AustraliaAdelaideAustralia
| | - Vitomir Kovanovic
- Centre for Change and Complexity in LearningUniversity of South AustraliaAdelaideAustralia
| | - Jorge González
- Departamento de EstadísticaPontificia Universidad Católica de ChileSantiago de ChileChile
| | - Thomas Kneib
- Campus Institute Data Science (CIDAS) and Chair of StatisticsGeorg‐August‐Universität GöttingenGöttingenGermany
| | | | - Lucas Kook
- Epidemiology, Biostatistics, and Prevention InstituteUniversity of ZurichZurichSwitzerland
- Institute of Data Analysis and Process DesignZurich University of Applied SciencesWinterthurSwitzerland
| | | | - Raydonal Ospina
- Department of Statistics, CASTLabFederal University of PernambucoRecifeBrazil
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Speller J, Staerk C, Mayr A. Robust statistical boosting with quantile-based adaptive loss functions. Int J Biostat 2022:ijb-2021-0127. [PMID: 35950232 DOI: 10.1515/ijb-2021-0127] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Accepted: 06/20/2022] [Indexed: 11/15/2022]
Abstract
We combine robust loss functions with statistical boosting algorithms in an adaptive way to perform variable selection and predictive modelling for potentially high-dimensional biomedical data. To achieve robustness against outliers in the outcome variable (vertical outliers), we consider different composite robust loss functions together with base-learners for linear regression. For composite loss functions, such as the Huber loss and the Bisquare loss, a threshold parameter has to be specified that controls the robustness. In the context of boosting algorithms, we propose an approach that adapts the threshold parameter of composite robust losses in each iteration to the current sizes of residuals, based on a fixed quantile level. We compared the performance of our approach to classical M-regression, boosting with standard loss functions or the lasso regarding prediction accuracy and variable selection in different simulated settings: the adaptive Huber and Bisquare losses led to a better performance when the outcome contained outliers or was affected by specific types of corruption. For non-corrupted data, our approach yielded a similar performance to boosting with the efficient L 2 loss or the lasso. Also in the analysis of skewed KRT19 protein expression data based on gene expression measurements from human cancer cell lines (NCI-60 cell line panel), boosting with the new adaptive loss functions performed favourably compared to standard loss functions or competing robust approaches regarding prediction accuracy and resulted in very sparse models.
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Affiliation(s)
- Jan Speller
- Medical Faculty, Institute of Medical Biometrics, Informatics and Epidemiology (IMBIE), University of Bonn, Bonn, Germany
| | - Christian Staerk
- Medical Faculty, Institute of Medical Biometrics, Informatics and Epidemiology (IMBIE), University of Bonn, Bonn, Germany
| | - Andreas Mayr
- Medical Faculty, Institute of Medical Biometrics, Informatics and Epidemiology (IMBIE), University of Bonn, Bonn, Germany
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Huber KJ, Vieira S, Sikorski J, Wüst PK, Fösel BU, Gröngröft A, Overmann J. Differential Response of Acidobacteria to Water Content, Soil Type, and Land Use During an Extended Drought in African Savannah Soils. Front Microbiol 2022; 13:750456. [PMID: 35222321 PMCID: PMC8874233 DOI: 10.3389/fmicb.2022.750456] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Accepted: 01/20/2022] [Indexed: 11/13/2022] Open
Abstract
Although climate change is expected to increase the extent of drylands worldwide, the effect of drought on the soil microbiome is still insufficiently understood as for dominant but little characterized phyla like the Acidobacteria. In the present study the active acidobacterial communities of Namibian soils differing in type, physicochemical parameters, and land use were characterized by high-throughput sequencing. Water content, pH, major ions and nutrients were distinct for sandy soils, woodlands or dry agriculture on loamy sands. Soils were repeatedly sampled over a 2-year time period and covered consecutively a strong rainy, a dry, a normal rainy and a weak rainy season. The increasing drought had differential effects on different soils. Linear modeling of the soil water content across all sampling locations and sampling dates revealed that the accumulated precipitation of the preceding season had only a weak, but statistically significant effect, whereas woodland and irrigation exerted a strong positive effect on water content. The decrease in soil water content was accompanied by a pronounced decrease in the fraction of active Acidobacteria (7.9-0.7%) while overall bacterial community size/cell counts remained constant. Notably, the strongest decline in the relative fraction of Acidobacteria was observed after the first cycle of rainy and dry season, rather than after the weakest rainy season at the end of the observation period. Over the 2-year period, also the β-diversity of soil Acidobacteria changed. During the first year this change in composition was related to soil type (loamy sand) and land use (woodland) as explanatory variables. A total of 188 different acidobacterial sequence variants affiliated with the "Acidobacteriia," Blastocatellia, and Vicinamibacteria changed significantly in abundance, suggesting either drought sensitivity or formation of dormant cell forms. Comparative physiological testing of 15 Namibian isolates revealed species-specific and differential responses in viability during long-term continuous desiccation or drying-rewetting cycles. These different responses were not determined by phylogenetic affiliation and provide a first explanation for the effect of drought on soil Acidobacteria. In conclusion, the response of acidobacterial communities to water availability is non-linear, most likely caused by the different physiological adaptations of the different taxa present.
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Affiliation(s)
- Katharina J. Huber
- Leibniz Institute DSMZ—German Collection of Microorganisms and Cell Cultures, Braunschweig, Germany
| | - Selma Vieira
- Leibniz Institute DSMZ—German Collection of Microorganisms and Cell Cultures, Braunschweig, Germany
| | - Johannes Sikorski
- Leibniz Institute DSMZ—German Collection of Microorganisms and Cell Cultures, Braunschweig, Germany
| | - Pia K. Wüst
- Leibniz Institute DSMZ—German Collection of Microorganisms and Cell Cultures, Braunschweig, Germany
| | - Bärbel U. Fösel
- Leibniz Institute DSMZ—German Collection of Microorganisms and Cell Cultures, Braunschweig, Germany
| | - Alexander Gröngröft
- Department of Geosciences, Institute of Soil Science, University of Hamburg, Hamburg, Germany
| | - Jörg Overmann
- Leibniz Institute DSMZ—German Collection of Microorganisms and Cell Cultures, Braunschweig, Germany
- Institute of Microbiology, Technical University Braunschweig, Braunschweig, Germany
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6
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Tyralis H, Papacharalampous G. Boosting algorithms in energy research: a systematic review. Neural Comput Appl 2021. [DOI: 10.1007/s00521-021-05995-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
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7
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Explanation and Probabilistic Prediction of Hydrological Signatures with Statistical Boosting Algorithms. REMOTE SENSING 2021. [DOI: 10.3390/rs13030333] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Hydrological signatures, i.e., statistical features of streamflow time series, are used to characterize the hydrology of a region. A relevant problem is the prediction of hydrological signatures in ungauged regions using the attributes obtained from remote sensing measurements at ungauged and gauged regions together with estimated hydrological signatures from gauged regions. The relevant framework is formulated as a regression problem, where the attributes are the predictor variables and the hydrological signatures are the dependent variables. Here we aim to provide probabilistic predictions of hydrological signatures using statistical boosting in a regression setting. We predict 12 hydrological signatures using 28 attributes in 667 basins in the contiguous US. We provide formal assessment of probabilistic predictions using quantile scores. We also exploit the statistical boosting properties with respect to the interpretability of derived models. It is shown that probabilistic predictions at quantile levels 2.5% and 97.5% using linear models as base learners exhibit better performance compared to more flexible boosting models that use both linear models and stumps (i.e., one-level decision trees). On the contrary, boosting models that use both linear models and stumps perform better than boosting with linear models when used for point predictions. Moreover, it is shown that climatic indices and topographic characteristics are the most important attributes for predicting hydrological signatures.
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8
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Adde A, Darveau M, Barker N, Cumming S. Predicting spatiotemporal abundance of breeding waterfowl across Canada: A Bayesian hierarchical modelling approach. DIVERS DISTRIB 2020. [DOI: 10.1111/ddi.13129] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Affiliation(s)
- Antoine Adde
- Department of Wood and Forest Sciences Laval University Quebec QC Canada
| | - Marcel Darveau
- Department of Wood and Forest Sciences Laval University Quebec QC Canada
- Ducks Unlimited Canada Quebec QC Canada
| | - Nicole Barker
- Canadian Wildlife Service Environment and Climate Change Canada Edmonton AB Canada
| | - Steven Cumming
- Department of Wood and Forest Sciences Laval University Quebec QC Canada
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Muggeo VM, Torretta F, Eilers PHC, Sciandra M, Attanasio M. Multiple smoothing parameters selection in additive regression quantiles. STAT MODEL 2020. [DOI: 10.1177/1471082x20929802] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
We propose an iterative algorithm to select the smoothing parameters in additive quantile regression, wherein the functional forms of the covariate effects are unspecified and expressed via B-spline bases with difference penalties on the spline coefficients. The proposed algorithm relies on viewing the penalized coefficients as random effects from the symmetric Laplace distribution, and it turns out to be very efficient and particularly attractive with multiple smooth terms. Through simulations we compare our proposal with some alternative approaches, including the traditional ones based on minimization of the Schwarz Information Criterion. A real-data analysis is presented to illustrate the method in practice.
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Affiliation(s)
- Vito M.R. Muggeo
- Dipartimento di Scienze Economiche, Aziendali e Statistiche, University of Palermo, Palermo, Italy
| | - Federico Torretta
- Dipartimento di Scienze Economiche, Aziendali e Statistiche, University of Palermo, Palermo, Italy
| | | | - Mariangela Sciandra
- Dipartimento di Scienze Economiche, Aziendali e Statistiche, University of Palermo, Palermo, Italy
| | - Massimo Attanasio
- Dipartimento di Scienze Economiche, Aziendali e Statistiche, University of Palermo, Palermo, Italy
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Menzenbach J, Guttenthaler V, Kirfel A, Ricchiuto A, Neumann C, Adler L, Kieback M, Velten L, Fimmers R, Mayr A, Wittmann M. Estimating patients' risk for postoperative delirium from preoperative routine data - Trial design of the PRe-Operative prediction of postoperative DElirium by appropriate SCreening (PROPDESC) study - A monocentre prospective observational trial. Contemp Clin Trials Commun 2019; 17:100501. [PMID: 31890984 PMCID: PMC6926123 DOI: 10.1016/j.conctc.2019.100501] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Revised: 11/14/2019] [Accepted: 11/21/2019] [Indexed: 11/09/2022] Open
Abstract
Background Postoperative Delirium (POD) is the most common complication of elderly patients after surgery associated with increased postoperative morbidity, persistent care dependency and even mortality. Prevention of POD requires detection of patients at high risk prior to surgery. PROPDESC intends to provide an instrument for preoperative routine screening of patients' risk for POD. Methods PROPDESC is a monocentric prospective observatory trial including 1000 patients older than 60 years from various disciplines of a university hospital planned for surgery of at least 60 min. To develop a score predicting the risk for POD, anesthesiological stratifications, laboratory values, medication and known risk factors as well as quality of life and cognitive performance are taken into account. POD assessment is performed daily on the first five days after the operation respectively the end of sedation in the intensive care units and normal wards. The score is evaluated from 600 data sets and subsequently validated internally. The most appropriate predictors are determined by a component-wise gradient boosting approach. Discussion Based on retrospective investigations, etiology of POD is considered multifactorial. By a prospective analysis of various factors, PROPDESC intends to provide an applicable tool to predict the risk for POD from preoperative routine data and assessment of cognitive function. Objective is to establish an automatically generating score in preoperative routine to screen patients for increased risk of POD as starting point for POD reduction and management. Model compilation requires a high significance and enhancement within compound as well as regular availability of the selected predictors. Trial registration DRKS, DRKS00015715. Registered 13 December 2018 - Retrospectively registered, https://www.drks.de/drks_web/navigate.do?navigationId=trial.HTML&TRIAL_ID=DRKS00015715.
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Affiliation(s)
- Jan Menzenbach
- Clinic for Anesthesiology of University Hospital Bonn, Venusberg Campus 1, 53127, Bonn, Germany
| | - Vera Guttenthaler
- Clinic for Anesthesiology of University Hospital Bonn, Venusberg Campus 1, 53127, Bonn, Germany
| | - Andrea Kirfel
- Clinic for Anesthesiology of University Hospital Bonn, Venusberg Campus 1, 53127, Bonn, Germany
| | - Arcangelo Ricchiuto
- Institute for Medical Biometry, Informatics and Epidemiology at the University of Bonn, Venusberg Campus 1, 53127, Bonn, Germany
| | - Claudia Neumann
- Clinic for Anesthesiology of University Hospital Bonn, Venusberg Campus 1, 53127, Bonn, Germany
| | - Linda Adler
- Clinic for Anesthesiology of University Hospital Bonn, Venusberg Campus 1, 53127, Bonn, Germany
| | - Marjetka Kieback
- Clinic for Anesthesiology of University Hospital Bonn, Venusberg Campus 1, 53127, Bonn, Germany
| | - Lisa Velten
- Clinic for Anesthesiology of University Hospital Bonn, Venusberg Campus 1, 53127, Bonn, Germany
| | - Rolf Fimmers
- Institute for Medical Biometry, Informatics and Epidemiology at the University of Bonn, Venusberg Campus 1, 53127, Bonn, Germany
| | - Andreas Mayr
- Institute for Medical Biometry, Informatics and Epidemiology at the University of Bonn, Venusberg Campus 1, 53127, Bonn, Germany
| | - Maria Wittmann
- Clinic for Anesthesiology of University Hospital Bonn, Venusberg Campus 1, 53127, Bonn, Germany
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Abstract
Heterologously expressed genes require adaptation to the host organism to ensure adequate levels of protein synthesis, which is typically approached by replacing codons by the target organism’s preferred codons. In view of frequently encountered suboptimal outcomes we introduce the codon-specific elongation model (COSEM) as an alternative concept. COSEM simulates ribosome dynamics during mRNA translation and informs about protein synthesis rates per mRNA in an organism- and context-dependent way. Protein synthesis rates from COSEM are integrated with further relevant covariates such as translation accuracy into a protein expression score that we use for codon optimization. The scoring algorithm further enables fine-tuning of protein expression including deoptimization and is implemented in the software OCTOPOS. The protein expression score produces competitive predictions on proteomic data from prokaryotic, eukaryotic, and human expression systems. In addition, we optimized and tested heterologous expression of manA and ova genes in Salmonella enterica serovar Typhimurium. Superiority over standard methodology was demonstrated by a threefold increase in protein yield compared to wildtype and commercially optimized sequences.
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12
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Hepp T, Schmid M, Mayr A. Significance Tests for Boosted Location and Scale Models with Linear Base-Learners. Int J Biostat 2019; 15:/j/ijb.ahead-of-print/ijb-2018-0110/ijb-2018-0110.xml. [PMID: 30990787 DOI: 10.1515/ijb-2018-0110] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Accepted: 03/21/2019] [Indexed: 11/15/2022]
Abstract
Generalized additive models for location scale and shape (GAMLSS) offer very flexible solutions to a wide range of statistical analysis problems, but can be challenging in terms of proper model specification. This complex task can be simplified using regularization techniques such as gradient boosting algorithms, but the estimates derived from such models are shrunken towards zero and it is consequently not straightforward to calculate proper confidence intervals or test statistics. In this article, we propose two strategies to obtain p-values for linear effect estimates for Gaussian location and scale models based on permutation tests and a parametric bootstrap approach. These procedures can provide a solution for one of the remaining problems in the application of gradient boosting algorithms for distributional regression in biostatistical data analyses. Results from extensive simulations indicate that in low-dimensional data both suggested approaches are able to hold the type-I error threshold and provide reasonable test power comparable to the Wald-type test for maximum likelihood inference. In high-dimensional data, when gradient boosting is the only feasible inference for this model class, the power decreases but the type-I error is still under control. In addition, we demonstrate the application of both tests in an epidemiological study to analyse the impact of physical exercise on both average and the stability of the lung function of elderly people in Germany.
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Affiliation(s)
- Tobias Hepp
- Institut für medizinische Biometrie, Informatik und Epidemiologie, Medizinische Fakultät, Rheinische Friedrich-Wilhelms-Universität Bonn, Bonn, Germany.,Institut für Medizininformatik, Biometrie und Epidemiologie, Medizinische Fakultät, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Matthias Schmid
- Institut für medizinische Biometrie, Informatik und Epidemiologie, Medizinische Fakultät, Rheinische Friedrich-Wilhelms-Universität Bonn, Bonn, Germany
| | - Andreas Mayr
- Institut für medizinische Biometrie, Informatik und Epidemiologie, Medizinische Fakultät, Rheinische Friedrich-Wilhelms-Universität Bonn, Bonn, Germany
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Smith A, Hofner B, Lamb JS, Osenkowski J, Allison T, Sadoti G, McWilliams SR, Paton P. Modeling spatiotemporal abundance of mobile wildlife in highly variable environments using boosted GAMLSS hurdle models. Ecol Evol 2019; 9:2346-2364. [PMID: 30891185 PMCID: PMC6405508 DOI: 10.1002/ece3.4738] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Revised: 10/11/2018] [Accepted: 10/30/2018] [Indexed: 11/07/2022] Open
Abstract
Modeling organism distributions from survey data involves numerous statistical challenges, including accounting for zero-inflation, overdispersion, and selection and incorporation of environmental covariates. In environments with high spatial and temporal variability, addressing these challenges often requires numerous assumptions regarding organism distributions and their relationships to biophysical features. These assumptions may limit the resolution or accuracy of predictions resulting from survey-based distribution models. We propose an iterative modeling approach that incorporates a negative binomial hurdle, followed by modeling of the relationship of organism distribution and abundance to environmental covariates using generalized additive models (GAM) and generalized additive models for location, scale, and shape (GAMLSS). Our approach accounts for key features of survey data by separating binary (presence-absence) from count (abundance) data, separately modeling the mean and dispersion of count data, and incorporating selection of appropriate covariates and response functions from a suite of potential covariates while avoiding overfitting. We apply our modeling approach to surveys of sea duck abundance and distribution in Nantucket Sound (Massachusetts, USA), which has been proposed as a location for offshore wind energy development. Our model results highlight the importance of spatiotemporal variation in this system, as well as identifying key habitat features including distance to shore, sediment grain size, and seafloor topographic variation. Our work provides a powerful, flexible, and highly repeatable modeling framework with minimal assumptions that can be broadly applied to the modeling of survey data with high spatiotemporal variability. Applying GAMLSS models to the count portion of survey data allows us to incorporate potential overdispersion, which can dramatically affect model results in highly dynamic systems. Our approach is particularly relevant to systems in which little a priori knowledge is available regarding relationships between organism distributions and biophysical features, since it incorporates simultaneous selection of covariates and their functional relationships with organism responses.
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Affiliation(s)
- Adam Smith
- Department of Natural Resources ScienceUniversity of Rhode IslandKingstonRhode Island
- Present address:
United States Fish and Wildlife Service, National Wildlife Refuge SystemInventory and Monitoring BranchAthensGeorgia
| | - Benjamin Hofner
- Department of Medical Informatics, Biometry and EpidemiologyFriedrich‐Alexander‐University Erlangen‐NurembergErlangenGermany
- Present address:
Section BiostatisticsPaul‐Ehrlich‐InstitutLangenGermany
| | - Juliet S. Lamb
- Department of Natural Resources ScienceUniversity of Rhode IslandKingstonRhode Island
| | - Jason Osenkowski
- Rhode Island Department of Environmental ManagementWest KingstonRhode Island
| | - Taber Allison
- American Wind Wildlife InstituteWashingtonDistrict of Columbia
| | | | - Scott R. McWilliams
- Department of Natural Resources ScienceUniversity of Rhode IslandKingstonRhode Island
| | - Peter Paton
- Department of Natural Resources ScienceUniversity of Rhode IslandKingstonRhode Island
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Abstract
Abstract: Quantile regression quantifies the association of explanatory variables with a conditional quantile of a dependent variable without assuming any specific conditional distribution. It hence models the quantiles, instead of the mean as done in standard regression. In cases where either the requirements for mean regression, such as homoscedasticity, are violated or interest lies in the outer regions of the conditional distribution, quantile regression can explain dependencies more accurately than classical methods. However, many quantile regression papers are rather theoretical so the method has still not become a standard tool in applications. In this article, we explain quantile regression from an applied perspective. In particular, we illustrate the concept, advantages and disadvantages of quantile regression using two datasets as examples.
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Affiliation(s)
- Elisabeth Waldmann
- Department of Medical Informatics,
Biometry and Epidemiology, Friedrich-Alexander-Universität,
Erlangen-Nürnberg,Germany
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Abstract
Abstract: Bayesian methods have become increasingly popular in the past two decades. With the constant rise of computational power, even very complex models can be estimated on virtually any modern computer. Moreover, interest has shifted from conditional mean models to probabilistic distributional models capturing location, scale, shape and other aspects of a response distribution, where covariate effects can have flexible forms, for example, linear, non-linear, spatial or random effects. This tutorial article discusses how to select models in the Bayesian distributional regression setting, how to monitor convergence of the Markov chains and how to use simulation-based inference also for quantities derived from the original model parametrization. We exemplify the workflow using daily weather data on (a) temperatures on Germany's highest mountain and (b) extreme values of precipitation for the whole of Germany.
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Affiliation(s)
- Nikolaus Umlauf
- Department of Statistics, Faculty of
Economics and Statistics, Universität Innsbruck, Austria
| | - Thomas Kneib
- Chairs of Statistics and Econometrics,
Georg-August-Universität Göttingen, Germany
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Abstract
Abstract: This tutorial article demonstrates how time-to-event data can be modelled in a very flexible way by taking advantage of advanced inference methods that have recently been developed for generalized additive mixed models. In particular, we describe the necessary pre-processing steps for transforming such data into a suitable format and show how a variety of effects, including a smooth nonlinear baseline hazard, and potentially nonlinear and nonlinearly time-varying effects, can be estimated and interpreted. We also present useful graphical tools for model evaluation and interpretation of the estimated effects. Throughout, we demonstrate this approach using various application examples. The article is accompanied by a new R -package called pammtools implementing all of the tools described here.
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Affiliation(s)
- Andreas Bender
- Department of Statistics,
Ludwig-Maximilians-Universität, München, Germany
| | - Andreas Groll
- Chairs of Statistics and Econometrics,
Georg-August-Universität Göttingen, Germany
| | - Fabian Scheipl
- Department of Statistics,
Ludwig-Maximilians-Universität, München, Germany
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