Moore Gary W, Meijer Daniëlle, Griffiths Margaret, Rushen Lucy, Brown Alice, Budde Ulrich, Dittmer Rita, Schocke Barbara, Leyte Anja, Geiter Sabine, Moes Anneke, Cutler Jacqueline A, Binder Nikolaus B
Diagnostic Haemostasis and Thrombosis, Viapath Analytics, Guy's & St. Thomas' Hospitals, London, UK.
Specialist Haemostasis Unit, Addenbrooke's Hospital, Cambridge, UK.
J Thromb Haemost. 2020 Jul;18(7):1686-1694. doi: 10.1111/jth.14815. Epub 2020 May 4.
Quantifying A disintegrin-like and metalloprotease with thrombospondin type 1 motif, member 13 (ADAMTS-13) activity enhances thrombotic thrombocytopenic purpura (TTP) diagnosis but most assays are time consuming, technically demanding, and mainly available in reference centers.
Evaluate a simple, semiquantitative ADAMTS-13 activity screening test for early identification/exclusion of TTP.
PATIENTS/METHODS: Plasma from 220 patients with suspected thrombotic microangiopathy at three reference centers were tested with TECHNOSCREEN ADAMTS13 activity screening test in comparison with TECHNOZYM ADAMTS-13 activity ELISA at two centers, and in-house fluorescence resonance energy transfer assay at the third center. The screening test indicates if ADAMTS-13 activity is at one of four level-indicator points: 0, 0.1, 0.4, or 0.8 IU/mL.
Screen results were interpreted as binary data in that ADAMTS-13 activity was above or below the 0.1 IU/mL TTP clinical threshold. Combining all sites' data, the screen exhibited 88.7% sensitivity, 90.4% specificity, 74.6% positive predictive value, and 96.2% negative predictive value, comparable to published data for quantitative assays. Five samples with quantitative results below the threshold gave screen readings of 0.1 IU/mL and seven marginally above the threshold gave screen readings of zero. All would warrant plasma exchange while the level is quantified. Nine samples with normal/near normal results gave screens of zero and confirmatory quantifications would prompt early treatment withdrawal, as is current practice. One sample generated screen/quantitative results of 0.4/0.00 IU/mL respectively and was the only clear false-negative.
The screening test provides more rapid ADAMTS-13 level evaluation than most currently available assays. Its simple operation renders it suitable for adoption in routine or specialist laboratory environments.
