Limits of agreement between measures obtained from standard laboratory and the point-of-care device Hemochron Signature Elite(R) during acute haemorrhage

Abstract

Background: Rapid diagnosis of coagulopathy in the bleeding patient using point-of-care (POC) devices would be ideal. The Hemochron Signature Elite(®) (HC(®)) is a POC device that determines international normalized ratio (INR) and activated partial thromboplastin time (aPTT). The aim of the study was to evaluate the agreement for INR and aPTT between the HC(®) and standard laboratory values in acute haemorrhage.

Methods: This was a single-centre observational prospective study including patients with acute haemorrhage. Laboratory INR and aPTT were compared with simultaneous measurements performed with the HC(®). The diagnostic performance of HC(®) was determined; bias and limits of agreement were calculated according to the method of Bland and Altman.

Results: Seventy-two pairs of measurements from 39 patients were analysed. The bias between the INR-HC(®) and aPTT-HC(®) measurements and the central laboratory were 0.02 and -1.13, respectively. The Spearman's correlation coefficients for the INR-HC(®)/INR-lab and the aPTT-HC(®)/aPTT-lab were 0.68 and -0.29, respectively. Twenty-seven per cent of INR-HC(®) values and 89% of the aPTT-HC(®) values exceeded the predefined limits of agreement. The INR-HC(®) measurement identified patients with a central laboratory INR >1.5 with a sensitivity, specificity, and positive and negative predictive values of 83%, 70%, 76%, and 77%, respectively.

Conclusions: The results showed a lack of agreement between the INR-HC(®) and the aPTT-HC(®) measurements and the standard laboratory in the context of acute haemorrhage. The INR-HC(®) showed moderate performance as a decision-making tool to detect coagulopathy in the context of acute haemorrhage.

Keywords: blood coagulation disorders; haemorrhage; injuries; point-of-care systems; surgical blood loss.