Preparation of control blood for external quality assessment of point-of-care international normalized ratio testing in the Netherlands.

OBJECTIVES The aim of this study was to prepare control blood for an external quality assessment scheme (EQAS) for international normalized ratio (INR) point-of-care testing (POCT) in the Netherlands and to assess the performance of the participants. METHODS Control blood was prepared from dialyzed pooled patient plasma and washed human erythrocytes. Samples of control blood were mailed to participants of the Netherlands EQAS from October 2006 through December 2012. RESULTS Most participants used CoaguChek XS (Roche Diagnostics, Mannheim, Germany) devices for POCT. The median between-center coefficient of variation (CV) of the reported INR decreased from 4.5% in 2006 to 2.6% in 2012. A few participants used the ProTime Microcoagulation System (ITC, Edison, NJ) for POCT. The median CV (per year) of the INR with the latter system was 7.0% to 10.6%. CONCLUSIONS The control blood samples were useful for external quality assessment in the Netherlands. The participants' performance with the CoaguChek XS system improved with time, demonstrating the value of external quality assessment.