Point-of-care coagulometry in prehospital emergency patients – are international normalized ratios useful?

Excerpt

With great interest we read the recent article of Beynon et al. [1]. The authors aimed to assess the validity of a point-of-care (POC) coagulometer measuring international normalized ratios (INR) utilized in a prehospital setting. Indeed, there is a great potential for POC tests in emergency patients and only few studies have been conducted. Although the authors highlighted limitations of their own study and the relevance of INR itself, we feel that the study has further important limitations seriously restricting the implications. Most important, the validity of a test is defined as the degree to which an instrument measures the construct it purports to measure, and this objective was not defined [2]. A coagulopathy in general does not exist and prothrombin times (PT) are not established tests for a coagulopathy in general. Since INR was developed only to monitor long-term treatment of vitamin K antagonists (VKA), effects of other coagulation conditions, i.e., antiplatelet treatment, thrombocytopenia, hyperfibrinolysis or inherited platelet disorders can not be detected by INR measurements. A possible application for POC coagulometers in the prehospital setting is to assess INR in emergency patients treated with VKA. However, this issue was extensively studied in large (non-emergency) cohorts involving appropriate sample sizes and valid study designs [3, 4]. …