Peggy Nguyen, MD

Webb AJS, Ullman NL, Morgan TC, Muschelli J, Kornbluth J, Awad IA, et al. Accuracy of the ABC/2 Score for Intracerebral Hemorrhage: Systematic Review and Analysis of MISTIE, CLEAR-IVH, and CLEAR III. Stroke. 2015

The ABC/2 score is a simple method used by both clinicians and researchers to assess intracranial hemorrhage (ICH) size; however, the score has only been validated in small research cohorts. In this study, Webb et al. perform an analysis and systematic review of the validity of the ABC/2 score in three large clinical trials, MISTIE, CLEAR-IVH, and CLEAR III to address whether the ABC/2 score, in both a specialized reading center (RC) as well as a local research site, is an accurate and valid score for determining ICH volume as well as eligibility and clot resolution in trials for ICH.

In their analysis of 4369 scans, the authors found that, when compared to the reference-standard of CT-based planimetry (CTP), both RC-ABC/2 scores as well as site-ABC/2 scores were valid measures of ICH volume for eligibility and clot resolution in all trials. Specifically, RC-ABC/2 scores had good accuracy in defining ICH volume, and categorizing ICH volume as mild, moderate, or severe. Site-ABC/2 scores were less accurate, but still acceptable. ABC/2 scores tended to be less accurate with lobar hemorrhages, larger ICHs, and irregular or heterogenous clots, a conclusion also supported in part by their systematic review, which, although too heterogenous for quantitative analysis, did identify ten studies, of which 2 found greater errors with larger ICHs, and 2 found greater errors with more irregular ICHs.

This study is the largest validation of the ABC/2 score, providing good evidence that the ABC/2 score, which can be performed easily, is accurate and valid. Keeping in mind its possible limitations in certain types of ICH (lobar, larger and more irregular size), this gives clinicians and researchers greater confidence in using the ABC/2 score both in clinical practice and in research, especially in smaller settings where more accurate CT based measurements may not be quickly feasible.