Point-of-care testing : is it a paradox in international normalised ratio measurements?

Abstract

Point-of-care testing (POCT) in haemostasis has shown a steady state increase in the range of tests available with an exponential increase in the number of tests that are performed annually. The most commonly performed test remains the out of hospital measurement of the international normalised ratio (INR). The INR is used to monitor oral anticoagulation therapy (OAT) with vitamin K antagonists. Such drugs include some of the following: warfarin (Coumadin®), phenprocoumon (Marcumar®) and acenocoumarol (Sintrom®, also sold as other brand names). Contrary to laboratory testing, POCT is often performed by general practitioners (GPs), nurses, pharmacists, patients and other healthcare professionals. In many cases these individuals do not have access to the same support mechanisms that exist in the clinical laboratory regarding strict quality control programmes. When an INR test is performed in the clinical laboratory, it has to be accredited, monitored and inspected. Accreditation is also advisable and part of these requirements is to be involved in external quality assessment (EQA). In the case of POCT haemostasis assays, EQA programmes do exist, however these programmes are still relatively few in number. Over the last decade there has been a significant increase in the scope of POCT, particularly in the field of haemostasis. This brief review summarises POCT in haemostasis, highlighting some of its benefits, challenges and future perspectives, especially with regard to the measurement of the INR.