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Articles by Johannes Schroder
Total Records ( 2 ) for Johannes Schroder
  Niklas Mattsson , Ulf Andreasson , Staffan Persson , Hiroyuki Arai , Sat Dev Batish , Sergio Bernardini , Luisella Bocchio- Chiavetto , Marinus A. Blankenstein , Maria C. Carrillo , Sonia Chalbot , Els Coart , Davide Chiasserini , Neal Cutler , Gunilla Dahlfors , Stefan Duller , Anne M. Fagan , Orestes Forlenza , Giovanni B. Frisoni , Douglas Galasko , Daniela Galimberti , Harald Hampel , Aase Handberg , Michael T. Heneka , Adrianna Z. Herskovits , Sanna-Kaisa Herukka , David M. Holtzman , Christian Humpel , Bradley T. Hyman , Khalid Iqbal , Khalid Iqbal , Stephan A. Kaeser , Elmar Kaiser , Elisabeth Kapaki , Daniel Kidd , Peter Klivenyi , Cindy S. Knudsen , Markus P. Kummer , James Lui , Albert Llado , Piotr Lewczuk , Qiao-Xin Li , Ralph Martins , Colin Masters , John McAuliffe , Marc Mercken , Abhay Moghekar , Jose Luis Molinuevo , Thomas J. Montine , William Nowatzke , Richard O’Brien , Markus Otto , George P. Paraskevas , Lucilla Parnetti , Ronald C. Petersen , David Prvulovic , Herman P.M. de Reus , Robert A. Rissman , Elio Scarpini , Alessandro Stefani , Hilkka Soininen , Johannes Schroder , Leslie M. Shaw , Anders Skinningsrud , Brith Skrogstad and Annette Spreer
  Background The cerebrospinal fluid (CSF) biomarkers amyloid β (Aβ)-42, total-tau (T-tau), and phosphorylated-tau (P-tau) demonstrate good diagnostic accuracy for Alzheimer‘s disease (AD). However, there are large variations in biomarker measurements between studies, and between and within laboratories. The Alzheimer‘s Association has initiated a global quality control program to estimate and monitor variability of measurements, quantify batch-to-batch assay variations, and identify sources of variability. In this article, we present the results from the first two rounds of the program. Methods The program is open for laboratories using commercially available kits for Aβ, T-tau, or P-tau. CSF samples (aliquots of pooled CSF) are sent for analysis several times a year from the Clinical Neurochemistry Laboratory at the Molndal campus of the University of Gothenburg, Sweden. Each round consists of three quality control samples. Results Forty laboratories participated. Twenty-six used INNOTEST enzyme-linked immunosorbent assay kits, 14 used Luminex xMAP with the INNO-BIA AlzBio3 kit (both measure Aβ-(1-42), P-tau(181P), and T-tau), and 5 used Meso Scale Discovery with the Aβ triplex (AβN-42, AβN-40, and AβN-38) or T-tau kits. The total coefficients of variation between the laboratories were 13% to 36%. Five laboratories analyzed the samples six times on different occasions. Within-laboratory precisions differed considerably between biomarkers within individual laboratories. Conclusions Measurements of CSF AD biomarkers show large between-laboratory variability, likely caused by factors related to analytical procedures and the analytical kits. Standardization of laboratory procedures and efforts by kit vendors to increase kit performance might lower variability, and will likely increase the usefulness of CSF AD biomarkers.
  Niklas Mattsson , Ulf Andreasson , Staffan Persson , Maria C. Carrillo , Steven Collins , Sonia Chalbot , Neal Cutler , Diane Dufour- Rainfray , Anne M. Fagan , Niels H.H. Heegaard , Ging-Yuek Robin Hsiung , Bradley Hyman , Khalid Iqbal , D. Richard Lachno , Alberto Lleo , Piotr Lewczuk , Jose L. Molinuevo , Piero Parchi , Axel Regeniter , Robert Rissman , Hanna Rosenmann , Giuseppe Sancesario , Johannes Schroder , Leslie M. Shaw , Charlotte E. Teunissen , John Q. Trojanowski , Hugo Vanderstichele , Manu Vandijck , Marcel M. Verbeek , Henrik Zetterberg , Kaj Blennow and Stephan A. Kaser
  Background The cerebrospinal fluid (CSF) biomarkers amyloid beta 1–42, total tau, and phosphorylated tau are used increasingly for Alzheimer's disease (AD) research and patient management. However, there are large variations in biomarker measurements among and within laboratories. Methods Data from the first nine rounds of the Alzheimer's Association quality control program was used to define the extent and sources of analytical variability. In each round, three CSF samples prepared at the Clinical Neurochemistry Laboratory (Molndal, Sweden) were analyzed by single-analyte enzyme-linked immunosorbent assay (ELISA), a multiplexing xMAP assay, or an immunoassay with electrochemoluminescence detection. Results A total of 84 laboratories participated. Coefficients of variation (CVs) between laboratories were around 20% to 30%; within-run CVs, less than 5% to 10%; and longitudinal within-laboratory CVs, 5% to 19%. Interestingly, longitudinal within-laboratory CV differed between biomarkers at individual laboratories, suggesting that a component of it was assay dependent. Variability between kit lots and between laboratories both had a major influence on amyloid beta 1–42 measurements, but for total tau and phosphorylated tau, between-kit lot effects were much less than between-laboratory effects. Despite the measurement variability, the between-laboratory consistency in classification of samples (using prehoc-derived cutoffs for AD) was high (>90% in 15 of 18 samples for ELISA and in 12 of 18 samples for xMAP). Conclusions The overall variability remains too high to allow assignment of universal biomarker cutoff values for a specific intended use. Each laboratory must ensure longitudinal stability in its measurements and use internally qualified cutoff levels. Further standardization of laboratory procedures and improvement of kit performance will likely increase the usefulness of CSF AD biomarkers for researchers and clinicians.
 
 
 
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