Analytical performance and user-friendliness of four point-of-care measuring systems for monitoring prothrombin time international normalized ratio in the hands of the intended users.

OBJECTIVES: Scandinavian evaluation of laboratory equipment for point of care testing (SKUP) provides objective and supplier-independent information about analytical quality and user-friendliness of point-of-care (POC) measuring systems. The evaluation reports are freely available online and are valuable tools when selecting fit-for-purpose POC equipment. In this study, we present an overview of the performance of four POC measuring systems for monitoring prothrombin time international normalized ratio (INR) assessed against updated analytical performance specifications (APSs).

METHODS: Primary healthcare centres (PHCCs) in Sweden and Norway did the practical work under real-life conditions. In each evaluation, 2-4 PHCCs participated with at least 40 patients on Warfarin treatment per site. Capillary samples were measured on the POC INR systems (qLabs Q3 Plus PT-INR Owren, Xprecia Stride, microINR or ProTime InRhythm), with venous samples analysed at hospital laboratories for comparison (STA-R Evolution or Sysmex CS5100). In the current study, APSs from SKUP, ISO 17593:2022, and CLSI POCT14-Ed2 were used. User-friendliness was assessed by addressing operational facilities, user-manual, time factors, and quality control.

RESULTS: Only microINR coagulometer met the APS for accuracy, while qLabs Q3 Plus PT-INR Owren and ProTime InRhythm met the repeatability criteria. Xprecia Stride scored highest on user-friendliness, whereas the other systems faced challenges with sample application and unclear error messages on the devices.

CONCLUSIONS: This study highlights the potential for improvements in POC INR measuring systems and underscores the importance of performing objective evaluations under real-life conditions.