Margherita Vacca1, Rui Li2, Ying Fu2, Wei Qiu3, Xiaobo Sun3, Yaping Yan4, Ke Li4, Markus Reindl5, Kathrin Schanda5, Nadja Baumgartner5, Douglas Sato6, Ana Paula6, Romain Marignier7, Anne Ruiz7, Emeric Hirlimann7, Lisa Malaise7, Lekha Pandit8, Abhijna Ballal8, Sara Mariotto9, Ho Jin Kim10, Jieun Chung10, Sang-Min Han10, Neelika Malavige11, Uvini Amarasekara11, Thashi Chang11, Alvaro Cobo Calvo12, Georgina Arrambide12, Sean Pittock13, Jeffrey Bennett14, Chiara Morandi1, Silvia Scaranzin1, Federica Zuliani1, Eléonore Vieillard15, MARK WOODHALL15, Ruta Cakla15, Maria Leite15, Jacqueline Palace15, Ruth Geraldes15, Gabriele De Luca15, Simon Rinaldi15, Matteo Gastaldi1, Patrick Waters15
1IRCCS Fondazione Istituto Neurologico Nazionale Casimiro Mondino, Pavia, Italy, 2Department of Neurology and Institute of Neurology, The First Affiliated Hospital of Fujian Medical University, Fuzhou, China, 3Department of Neurology of The Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, China, 4Key Laboratory of the Ministry of Education for Medicinal Resources and Natural Pharmaceutical Chemistry, College of Life Sciences, Shaanxi Normal University, Xi’an, China, 5Medical University of Innsbruck, 6Pontifical Catholic University of Rio Grande do Sul, 7Lyon University Hospital, 8Center for Advanced Neurological Research, KS Hegde Medical Academy, Nitte (deemed to be university), Mangalore, India, 9Neurology Unit, University of Verona, 10National Cancer Center, 11Department of Immunology and Molecular Medicine, Faculty of Medical Sciences, University of Sri Jayawardenepura, Sri Lanka, 12Neurology-Neuroimmunology Department, Multiple Sclerosis Centre of Catalonia (Cemcat), Vall d’Hebron Barcelona Hospital Campus, Barcelona, Spain, 13Mayo Clinic Dept of Neurology, 14University of Colorado School of Medicine, 15Nuffield Department of Clinical Neurosciences - University of Oxford
Objective:
Evaluate the analytic performances of a rapid immunodot assay (iDOT) for the identification of antibodies against AQP4 in patients with NMOSD.
Background:
NMOSD refers to an inflammatory condition of the central nervous system. IgG autoantibodies against AQP4 are pathogenic and diagnostic biomarkers for NMOSD; cell-based assays (CBAs) are the most widely used test for AQP4 antibodies detection.
Design/Methods:
Sera from centres in China, France, Italy, Korea, Spain, UK were sent coded to the coordinating centre in Italy from four patient groups (1. AQP4 antibody positive NMOSD patients 2. MOG-IgG clear positive MOGAD patients 3. Clinically definite pwMS 4. Sera difficult on any assay). iDOT kits from China were sent to Italy. All samples were recoded and shipped with kits to 8 testing centres (Austria, Brazil, India, Sri Lanka, France, China, Korea, UK). iDOTs were performed at all centres; lCBAs in Korea and UK; fCBA in China. Test sensitivity was based on positive results in group 1; specificity was based on negative results in groups 2–4.
Results:
Unblinding revealed 381 sera were tested: Group 1: 126, Group 2: 106, Group 3: 93, Group 4: 56. Kits were employed close to/after expiry date in seven centres. The median sensitivity was 84.9% (range 39.7-92.9%); median specificity was 99.2% (range 98.8-99.6%). 72% of group 1 samples were positive on all iDOTs across 7 centres with only 7 (6%) samples positive in fewer than 4/7 centres. The China team performed the assay on iDOT kits 2 months old with a sensitivity of 100% and specificity of 98.8%. The fCBA was 91.2% sensitive. lCBAs were 83.7% and 100% sensitive. All three were 100% specific.
Conclusions:
The iDOT kit performed well despite being near the end of their shelf-life. A relatively new kit performed in-house had equal sensitivity to the best lCBA and highlights great promise for this system.
Disclaimer: Abstracts were not reviewed by Neurology® and do not reflect the views of Neurology® editors or staff.