Evaluation of Point-of-care Activated Partial Thromboplastin Time Testing by Comparison to Laboratory-based Assay for Control of Intravenous Heparin

Introduction Patients on intravenous heparin require regular activated partial thromboplastin time monitoring. Laboratory-based activated partial thromboplastin time assays necessitate a delay between blood sampling and dose adjustment. Point-of-care testing could permit immediate dose adjustments, potentially enabling tighter control of anticoagulation. Aim To assess equivalence of activated partial thromboplastin time measured by conventional laboratory assay and by a novel proprietary point-of-care testing system (Hemochron Response, ITC, Thoratec Corporation, Edison, NJ) among surgical ward patients on intravenous heparin. Methods A total of 39 blood samples from patients on intravenous heparin were tested with both laboratory and point-of-care assays. Assay equivalence was assessed by Bland-Altman analysis. Results. Point-of-care measurements exceeded laboratory activated partial thromboplastin time by a mean of 15 seconds (standard deviation 19). In 19 cases (49%), the point-of-care measurement would have resulted in different heparin dosing from the laboratory activated partial thromboplastin time. Conclusions The Hemochron Response system is not sufficiently accurate for routine ward use compared with laboratory activated partial thromboplastin time assays.