Accuracy of the ABC/2 Score for Intracerebral Hemorrhage
Authors: Webb Alastair J.S. , Ullman Natalie L. , Morgan Tim C. , Muschelli John , Kornbluth Joshua , Awad Issam A. , Mayo Stephen , Rosenblum Michael , Ziai Wendy , Zuccarrello Mario , Aldrich Francois , John Sayona , Harnof Sagi , Lopez George , Broaddus William C. , Wijman Christine , Vespa Paul , Bullock Ross , Haines Stephen J. , Cruz-Flores Salvador , Tuhrim Stan , Hill Michael D. , Narayan Raj , Hanley Daniel F. , Tayal Ashis H. , Diaz Alberto Torres , Hoffer Alan , Moheet Asma , Agarwal Sachin , Markowski Mason , Rosenthal Guy , Kureshi Inam , Varelas Panayiotis , Cougo Pinto Pedro Telles , Marti-Fabregas Joan , Camarata Paul , Seder David B. , Freeman William , Helms Ann , Lazaridis Christos , Shahi Kavian , Sinclair David , Gizzi Martin , LeDoux David , Torbey Michel , Cockroft Kevin , Antezana David , Latorre Julius Gene , Margalit Nevo , Crabtree H. Mark , Lovick Darren , Venkatasubramanian Chitra , Weaver Michael , Jallo Jack , Reinert Michael , Butcher Ken , Leonardo Jody , Ardelt Agnieszka , Adeoye Opeolu , Csiba Laszlo , Wartenberg Katja , Bosel Julian , Testai Fernando , Adams Harold , Hobohm Carsten , Kerz Thomas , Wechsler Lawrence , Gardner Paul , Decker David , Bulters Diederik , Gonzales Nicole , Caron Jean-Louis , Hall Christiana , Ansari Safdar , Luft Andreas , Arikan Fuat , Graham R. Scott , Tucker Kristi 
Published: August 2015

Background and Purpose—
The ABC/2 score estimates intracerebral hemorrhage (ICH) volume, yet validations have been limited by small samples and inappropriate outcome measures. We determined accuracy of the ABC/2 score calculated at a specialized reading center (RC-ABC) or local site (site-ABC) versus the reference-standard computed tomography–based planimetry (CTP).

Methods—
In Minimally Invasive Surgery Plus Recombinant Tissue-Type Plasminogen Activator for Intracerebral Hemorrhage Evacuation-II (MISTIE-II), Clot Lysis Evaluation of Accelerated Resolution of Intraventricular Hemorrhage (CLEAR-IVH) and CLEAR-III trials. ICH volume was prospectively calculated by CTP, RC-ABC, and site-ABC. Agreement between CTP and ABC/2 was defined as an absolute difference up to 5 mL and relative difference within 20%. Determinants of ABC/2 accuracy were assessed by logistic regression.

Results—

In 4369 scans from 507 patients, CTP was more strongly correlated with RC-ABC (
r
2
=0.93) than with site-ABC (
r
2
=0.87). Although RC-ABC overestimated CTP-based volume on average (RC-ABC, 15.2 cm
3
; CTP, 12.7 cm3), agreement was reasonable when categorized into mild, moderate, and severe ICH (κ=0.75;
P
<0.001). This was consistent with overestimation of ICH volume in 6 of 8 previous studies. Agreement with CTP was greater for RC-ABC (84% within 5 mL; 48% of scans within 20%) than for site-ABC (81% within 5 mL; 41% within 20%). RC-ABC had moderate accuracy for detecting ≥5 mL change in CTP volume between consecutive scans (sensitivity, 0.76; specificity, 0.86) and was more accurate with smaller ICH, thalamic hemorrhage, and homogeneous clots.

Conclusions—
ABC/2 scores at local or central sites are sufficiently accurate to categorize ICH volume and assess eligibility for the CLEAR-III and MISTIE III studies and moderately accurate for change in ICH volume. However, accuracy decreases with large, irregular, or lobar clots.

Clinical Trial Registration—

URL:
http://www.clinicaltrials.gov
. Unique identifier: MISTIE-II NCT00224770; CLEAR-III NCT00784134.