PB0321 - Prospective evaluation of the HemosIL AcuStar ADAMTS13 Activity Assay

Sunday, June 25, 2023

18:30 – 19:30 ET

Room: Exhibition

Co-Author(s)

IM

Ilaria Mancini, PhD

Post-Doc Research Fellow
Università degli Studi di Milano, Department of Pathophysiology and Transplantation and Fondazione Luigi Villa, Milan, Italy
Milan, Lombardia, Italy

Co-Author(s)

SS

Sara Scardo

Statistician
Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico, Angelo Bianchi Bonomi Hemophilia and Thrombosis Center, Milan, Italy
Milan, Lombardia, Italy
MB

Marina Biganzoli

Lab Technician
former Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico, Angelo Bianchi Bonomi Hemophilia and Thrombosis Center, Milan, Italy
Milan, Lombardia, Italy
PD

Pasqualina De Leo

Research Fellow
Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico, Angelo Bianchi Bonomi Hemophilia and Thrombosis Center, Milan, Italy
Milan, Lombardia, Italy
AR

Alessandra Rallo

Research Fellow
Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico, Angelo Bianchi Bonomi Hemophilia and Thrombosis Center, Milan, Italy
Milan, Lombardia, Italy
Andrea Artoni, MD

MD
Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Angelo Bianchi Bonomi Hemophilia and Thrombosis Center, Milan, Italy
Milano, Lombardia, Italy
BF

Barbara Ferrari

MD
Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico, Angelo Bianchi Bonomi Hemophilia and Thrombosis Center, Milan, Italy
Milan, Lombardia, Italy
Juri Alessandro Giannotta, MD

Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico, Angelo Bianchi Bonomi Hemophilia and Thrombosis Center, Milan, Italy
Milano, Lombardia, Italy

Presenting Author(s)

Pasquale Agosti, MD, PhD

Università degli Studi di Milano, Department of Pathophysiology and Transplantation and Fondazione Luigi Villa, Milan, Italy
Milano, Lombardia, Italy

Co-Author(s)

Flora Peyvandi, MD, PhD (she/her/hers)

Director
IRCCS Ca' Granda Maggiore Hospital Foundation, Angelo Bianchi Bonomi Hemophilia and Thrombosis Center, Milano, Italy; Università degli Studi di Milano, Department of Pathophysiology and Transplantation, Milano, Italy
Milano, Lombardia, Italy

Background: ADAMTS13 activity testing is pivotal to confirm the diagnosis of thrombotic thrombocytopenic purpura (TTP) and guide optimal management during both the acute and remission phase. The HemosIL Acustar ADAMTS13 Activity Assay (Werfen), a rapid fully-automated ADAMTS13 activity assay, has been recently released on the market, warranting prospective evaluation of its performance.

Aims: To prospectively evaluate the performance of the Acustar ADAMTS13 Activity assay.

Methods: We performed a method comparison study between the Acustar and the FRETS-VWF73 assay, used as the reference method. We tested 130 samples from 93 patients referred to our center for ADAMTS13 testing between January and July 2022. Samples included 120 immune TTP (12 acute/108 remission), 3 congenital TTP, 6 non-TTP TMA, and 1 sample of unknown diagnosis, with ADAMTS13 activity values by FRETS-VWF73 ranging from < 3 to 119 IU/dl. Passing-Bablock linear regression and Bland-Altman analysis were used to estimate agreement and bias between the two methods in the 111 samples with quantifiable activity values. Concordance was assessed with Cohen’s Kappa coefficient, using the diagnostic 10 IU/dl ADAMTS13 activity cut-off.

Results: The slope and intercept of the Passing-Bablok regression were 1.03 (95%CI 0.96-1.13) and 4.17 (95%CI 1.05-6.84), respectively. The Bland-Altman analysis confirmed the presence of a statistically significant systematic bias, with a slight overestimation by the Acustar method (mean absolute bias 4.7 IU/dl [95%CI 2.4-7]). We observed 6 (5%) discordant samples between the two methods ( < 10 IU/dl by FRETS VWF73, within 10-20 IU/dl by Acustar), and an almost perfect agreement, as determined by a Kappa’s coefficient of 0.87. None of these discordant samples were from acute TTP patients.

Conclusion(s): The Acustar assay slightly overestimated ADAMTS13 activity compared with the FRETS-VWF73 assay. Overall, a high agreement between the two methods was found. The Acustar assay proved reliable for ADAMTS13 testing in TTP patients.