LIVIVO - The Search Portal for Life Sciences

zur deutschen Oberfläche wechseln
Advanced search

Search results

Result 1 - 7 of total 7

Search options

  1. Article ; Online: Mixture density networks for the indirect estimation of reference intervals

    Tobias Hepp / Jakob Zierk / Manfred Rauh / Markus Metzler / Sarem Seitz

    BMC Bioinformatics, Vol 23, Iss 1, Pp 1-

    2022  Volume 17

    Abstract: Abstract Background Reference intervals represent the expected range of physiological test results in a healthy population and are essential to support medical decision making. Particularly in the context of pediatric reference intervals, where ... ...

    Abstract Abstract Background Reference intervals represent the expected range of physiological test results in a healthy population and are essential to support medical decision making. Particularly in the context of pediatric reference intervals, where recruitment regulations make prospective studies challenging to conduct, indirect estimation strategies are becoming increasingly important. Established indirect methods enable robust identification of the distribution of “healthy” samples from laboratory databases, which include unlabeled pathologic cases, but are currently severely limited when adjusting for essential patient characteristics such as age. Here, we propose the use of mixture density networks (MDN) to overcome this problem and model all parameters of the mixture distribution in a single step. Results Estimated reference intervals from varying settings with simulated data demonstrate the ability to accurately estimate latent distributions from unlabeled data using different implementations of MDNs. Comparing the performance with alternative estimation approaches further highlights the importance of modeling the mixture component weights as a function of the input in order to avoid biased estimates for all other parameters and the resulting reference intervals. We also provide a strategy to generate partially customized starting weights to improve proper identification of the latent components. Finally, the application on real-world hemoglobin samples provides results in line with current gold standard approaches, but also suggests further investigations with respect to adequate regularization strategies in order to prevent overfitting the data. Conclusions Mixture density networks provide a promising approach capable of extracting the distribution of healthy samples from unlabeled laboratory databases while simultaneously and explicitly estimating all parameters and component weights as non-linear functions of the covariate(s), thereby allowing the estimation of age-dependent reference intervals in a single ...
    Keywords Mixture density networks ; Reference intervals ; Latent class regression ; Distributional regression ; Computer applications to medicine. Medical informatics ; R858-859.7 ; Biology (General) ; QH301-705.5
    Subject code 310
    Language English
    Publishing date 2022-07-01T00:00:00Z
    Publisher BMC
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

    More links

    Kategorien

  2. Book ; Online ; Thesis: Der Einfluss von türkischer Herkunft auf hämatologische Referenzintervalle in der deutschen Bevölkerung

    Mayr, Franz Xaver [Verfasser] / Jakob, Zierk [Akademischer Betreuer] / Jakob, Zierk [Gutachter] / Markus, Metzler [Gutachter]

    2023  

    Author's details Franz Xaver Mayr ; Gutachter: Zierk Jakob, Metzler Markus ; Betreuer: Zierk Jakob
    Keywords Medizin, Gesundheit ; Medicine, Health
    Subject code sg610
    Language German
    Publisher Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU)
    Publishing place Erlangen
    Document type Book ; Online ; Thesis
    Database Digital theses on the web

    More links

    Kategorien

  3. Article ; Online: Latent class distributional regression for the estimation of non-linear reference limits from contaminated data sources

    Tobias Hepp / Jakob Zierk / Manfred Rauh / Markus Metzler / Andreas Mayr

    BMC Bioinformatics, Vol 21, Iss 1, Pp 1-

    2020  Volume 15

    Abstract: Abstract Background Medical decision making based on quantitative test results depends on reliable reference intervals, which represent the range of physiological test results in a healthy population. Current methods for the estimation of reference ... ...

    Abstract Abstract Background Medical decision making based on quantitative test results depends on reliable reference intervals, which represent the range of physiological test results in a healthy population. Current methods for the estimation of reference limits focus either on modelling the age-dependent dynamics of different analytes directly in a prospective setting or the extraction of independent distributions from contaminated data sources, e.g. data with latent heterogeneity due to unlabeled pathologic cases. In this article, we propose a new method to estimate indirect reference limits with non-linear dependencies on covariates from contaminated datasets by combining the framework of mixture models and distributional regression. Results Simulation results based on mixtures of Gaussian and gamma distributions suggest accurate approximation of the true quantiles that improves with increasing sample size and decreasing overlap between the mixture components. Due to the high flexibility of the framework, initialization of the algorithm requires careful considerations regarding appropriate starting weights. Estimated quantiles from the extracted distribution of healthy hemoglobin concentration in boys and girls provide clinically useful pediatric reference limits similar to solutions obtained using different approaches which require more samples and are computationally more expensive. Conclusions Latent class distributional regression models represent the first method to estimate indirect non-linear reference limits from a single model fit, but the general scope of applications can be extended to other scenarios with latent heterogeneity.
    Keywords Latent class regression ; Finite mixture models ; Distributional regression ; Reference limits ; Computer applications to medicine. Medical informatics ; R858-859.7 ; Biology (General) ; QH301-705.5
    Subject code 310
    Language English
    Publishing date 2020-11-01T00:00:00Z
    Publisher BMC
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

    More links

    Kategorien

  4. Article ; Online: refineR

    Tatjana Ammer / André Schützenmeister / Hans-Ulrich Prokosch / Manfred Rauh / Christopher M. Rank / Jakob Zierk

    Scientific Reports, Vol 11, Iss 1, Pp 1-

    A Novel Algorithm for Reference Interval Estimation from Real-World Data

    2021  Volume 17

    Abstract: Abstract Reference intervals are essential for the interpretation of laboratory test results in medicine. We propose a novel indirect approach to estimate reference intervals from real-world data as an alternative to direct methods, which require samples ...

    Abstract Abstract Reference intervals are essential for the interpretation of laboratory test results in medicine. We propose a novel indirect approach to estimate reference intervals from real-world data as an alternative to direct methods, which require samples from healthy individuals. The presented refineR algorithm separates the non-pathological distribution from the pathological distribution of observed test results using an inverse approach and identifies the model that best explains the non-pathological distribution. To evaluate its performance, we simulated test results from six common laboratory analytes with a varying location and fraction of pathological test results. Estimated reference intervals were compared to the ground truth, an alternative indirect method (kosmic), and the direct method (N = 120 and N = 400 samples). Overall, refineR achieved the lowest mean percentage error of all methods (2.77%). Analyzing the amount of reference intervals within ± 1 total error deviation from the ground truth, refineR (82.5%) was inferior to the direct method with N = 400 samples (90.1%), but outperformed kosmic (70.8%) and the direct method with N = 120 (67.4%). Additionally, reference intervals estimated from pediatric data were comparable to published direct method studies. In conclusion, the refineR algorithm enables precise estimation of reference intervals from real-world data and represents a viable complement to the direct method.
    Keywords Medicine ; R ; Science ; Q
    Subject code 310
    Language English
    Publishing date 2021-08-01T00:00:00Z
    Publisher Nature Portfolio
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

    More links

    Kategorien

  5. Article ; Online: Influence of Turkish origin on hematology reference intervals in the German population

    Franz X. Mayr / Alexander Bertram / Holger Cario / Michael C. Frühwald / Hans-Jürgen Groß / Arndt Groening / Stefanie Grützner / Thomas Gscheidmeier / Reinhard Hoffmann / Alexander Krebs / Hans-Georg Ruf / Antje Torge / Joachim Woelfle / Oliver Razum / Manfred Rauh / Markus Metzler / Jakob Zierk

    Scientific Reports, Vol 11, Iss 1, Pp 1-

    2021  Volume 8

    Abstract: Abstract Reference intervals for laboratory test results have to be appropriate for the population in which they are used to be clinically useful. While sex and age are established partitioning criteria, patients’ origin also influences laboratory test ... ...

    Abstract Abstract Reference intervals for laboratory test results have to be appropriate for the population in which they are used to be clinically useful. While sex and age are established partitioning criteria, patients’ origin also influences laboratory test results, but is not commonly considered when creating or applying reference intervals. In the German population, stratification for ethnicity is rarely performed, and no ethnicity-specific hematology reference intervals have been reported yet. In this retrospective study, we investigated whether specific reference intervals are warranted for the numerically largest group of non-German descent, individuals originating from Turkey. To this end, we analyzed 1,314,754 test results from 167,294 patients from six German centers. Using a name-based algorithm, 1.9% of patients were identified as originating from Turkey, in line with census data and the algorithm’s sensitivity. Reference intervals and their confidence intervals were calculated using an indirect data mining approach, and Turkish and non-Turkish reference limits overlapped completely or partially in nearly all analytes, regardless of age and sex, and only 5/144 (3.5%) subgroups’ reference limits showed no overlap. We therefore conclude that the current practice of using common reference intervals is appropriate and allows correct clinical decision-making in patients originating from Turkey.
    Keywords Medicine ; R ; Science ; Q
    Subject code 310
    Language English
    Publishing date 2021-10-01T00:00:00Z
    Publisher Nature Portfolio
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

    More links

    Kategorien

  6. Article ; Online: Correction

    Julian Gruendner / Thorsten Schwachhofer / Phillip Sippl / Nicolas Wolf / Marcel Erpenbeck / Christian Gulden / Lorenz A Kapsner / Jakob Zierk / Sebastian Mate / Michael Stürzl / Roland Croner / Hans-Ulrich Prokosch / Dennis Toddenroth

    PLoS ONE, Vol 14, Iss 11, p e

    KETOS: Clinical decision support and machine learning as a service - A training and deployment platform based on Docker, OMOP-CDM, and FHIR Web Services.

    2019  Volume 0225442

    Abstract: This corrects the article DOI:10.1371/journal.pone.0223010.]. ...

    Abstract [This corrects the article DOI:10.1371/journal.pone.0223010.].
    Keywords Medicine ; R ; Science ; Q
    Language English
    Publishing date 2019-01-01T00:00:00Z
    Publisher Public Library of Science (PLoS)
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

    More links

    Kategorien

  7. Article ; Online: KETOS

    Julian Gruendner / Thorsten Schwachhofer / Phillip Sippl / Nicolas Wolf / Marcel Erpenbeck / Christian Gulden / Lorenz A Kapsner / Jakob Zierk / Sebastian Mate / Michael Stürzl / Roland Croner / Hans-Ulrich Prokosch / Dennis Toddenroth

    PLoS ONE, Vol 14, Iss 10, p e

    Clinical decision support and machine learning as a service - A training and deployment platform based on Docker, OMOP-CDM, and FHIR Web Services.

    2019  Volume 0223010

    Abstract: BACKGROUND AND OBJECTIVE:To take full advantage of decision support, machine learning, and patient-level prediction models, it is important that models are not only created, but also deployed in a clinical setting. The KETOS platform demonstrated in this ...

    Abstract BACKGROUND AND OBJECTIVE:To take full advantage of decision support, machine learning, and patient-level prediction models, it is important that models are not only created, but also deployed in a clinical setting. The KETOS platform demonstrated in this work implements a tool for researchers allowing them to perform statistical analyses and deploy resulting models in a secure environment. METHODS:The proposed system uses Docker virtualization to provide researchers with reproducible data analysis and development environments, accessible via Jupyter Notebook, to perform statistical analysis and develop, train and deploy models based on standardized input data. The platform is built in a modular fashion and interfaces with web services using the Health Level 7 (HL7) Fast Healthcare Interoperability Resources (FHIR) standard to access patient data. In our prototypical implementation we use an OMOP common data model (OMOP-CDM) database. The architecture supports the entire research lifecycle from creating a data analysis environment, retrieving data, and training to final deployment in a hospital setting. RESULTS:We evaluated the platform by establishing and deploying an analysis and end user application for hemoglobin reference intervals within the University Hospital Erlangen. To demonstrate the potential of the system to deploy arbitrary models, we loaded a colorectal cancer dataset into an OMOP database and built machine learning models to predict patient outcomes and made them available via a web service. We demonstrated both the integration with FHIR as well as an example end user application. Finally, we integrated the platform with the open source DataSHIELD architecture to allow for distributed privacy preserving data analysis and training across networks of hospitals. CONCLUSION:The KETOS platform takes a novel approach to data analysis, training and deploying decision support models in a hospital or healthcare setting. It does so in a secure and privacy-preserving manner, combining the flexibility of ...
    Keywords Medicine ; R ; Science ; Q
    Subject code 004
    Language English
    Publishing date 2019-01-01T00:00:00Z
    Publisher Public Library of Science (PLoS)
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

    More links

    Kategorien

To top