Clinical and laboratory characteristics associated with a high optical density anti-platelet factor 4 ELISA test

• Main Authors: Lu BY, Kudlowitz D, Gardner LB
• Format: Article
• Language: English
• Published: Dove Medical Press 2015-11-01
• Series: Journal of Blood Medicine
• Online Access: https://www.dovepress.com/clinical-and-laboratory-characteristics-associated-with-a-high-optical-peer-reviewed-article-JBM

Benjamin Y Lu,1 David Kudlowitz,1, Lawrence B Gardner1–3 1Department of Medicine, 2Department of Biochemistry and Molecular Pharmacology, 3The Perlmutter Cancer Center, NYU Langone Medical Center, NYU School of Medicine, New York, NY, USA Purpose: Diagnosing heparin-induced thrombocytopenia, a potentially catastrophic immune-mediated disorder, continues to pose significant challenges for clinicians, as both clinical and laboratory tools lack specificity. There is mounting evidence supporting a positive correlation between definitive heparin-induced thrombocytopenia and optical density (OD) positivity from the widely available anti-platelet factor 4 enzyme-linked immunosorbent assays (PF4 ELISAs). However, the clinical features distinguishing these patients remain poorly understood. Patients and methods: To better characterize this group, we conducted a case-controlled, retrospective chart review of patients from two large, urban academic institutions who underwent a PF4 ELISA at a central laboratory. Associations between OD and 18 clinical characteristics were calculated using the Fisher's exact test for categorical variables and Wilcoxon rank-sum test for continuous variables. Results: In total, 184 negative patients (OD <0.7), and 121 positive patients (OD >0.7), including 74 low-positive patients (0.7, OD <1.4) and 47 high-positive patients (OD >1.4) were identified. Several clinical variables were significantly different in the negative group compared with the positive group, including hospital day (P<0.001), previous admission within the past 3 months (P<0.001), and the presence of a new thrombus (P=0.003). However, many of these variables were not different between the negative and low-positive group, and were only distinct between the negative and high-positive group. When the low-positive and high-positive groups were compared, only the 4T score was significantly different (P=0.003). Conclusion: These data indicate that those with OD >1.4 form a distinct clinical group and support the clinical utility of the 4T score. Keywords: heparin-induced thrombocytopenia, platelet factor 4 ELISA, thrombocytopenia, HIT, heparin