A national surveillance program for evaluating new reagent lots in medical laboratories.

Objectives: Differences between laboratory results attributable to the use of different reagent lots can potentially affect the diagnosis and monitoring of patients. To minimize patient risks, all laboratories should verify that new reagent lots meet agreed analytical performance specifications (APS). We propose a simplified, pragmatic approach for laboratories that involves compilating results into a national surveillance program, and present the first results obtained when applying this approach to troponins, glycated hemoglobin (HbA), prostate-specific antigen (PSA) and D-dimer.

Feasibility for aggregation of commutable external quality assessment results to evaluate metrological traceability and agreement among results.

Objectives: External quality assessment (EQA) with commutable samples is used for assessing agreement of results for patients' samples. We investigated the feasibility to aggregate results from four different EQA schemes to determine the bias between different measurement procedures and a reference target value.

Methods: We aggregated EQA results for creatinine from programs that used commutable EQA material by calculating the relative difference between individual participant results and the reference target value for each sample.

Pre-analytical practices for routine coagulation tests in European laboratories. A collaborative study from the European Organisation for External Quality Assurance Providers in Laboratory Medicine (EQALM).

Background Correct handling and storage of blood samples for coagulation tests are important to assure correct diagnosis and monitoring. The aim of this study was to assess the pre-analytical practices for routine coagulation testing in European laboratories. Methods In 2013-2014, European laboratories were invited to fill in a questionnaire addressing pre-analytical requirements regarding tube fill volume, citrate concentration, sample stability, centrifugation and storage conditions for routine coagulation testing (activated partial thromboplastin time [APTT], prothrombin time in seconds [PT-sec] and as international normalised ratio [PT-INR] and fibrinogen).

Self-management of warfarin therapy.

Background: Clinical studies from other countries show that self-management of warfarin therapy may reduce the risk of mortality, thromboembolism and complications when compared to conventional therapy. The purpose of this study was to train patients in self-management and compare the results with conventional therapy in Norway.

Method: A total of 23 patients who had previously been given conventional therapy by their GPs were instructed in how to measure INR (using the CoaguChek XS device) and administer warfarin dosage through a structured training programme over the course of 27 weeks.

Effect of coagulation factors on discrepancies in International Normalized Ratio results between instruments.

Background: The reasons for discrepancies between International Normalized Ratio (INR) results determined by point-of-care-instruments and laboratory measurements are not fully understood. In this study we investigated whether different levels of coagulation factors in the plasma of patients can explain some of the systematic and/or random parts of the difference in INR between the instruments.

Methods: Blood samples were collected at four different patient visits from each of 34 outpatients on warfarin treatment.

Discrepancies in international normalized ratio results between instruments: a model to split the variation into subcomponents.

Background: Observed differences between results obtained from comparison of instruments used to measure international normalized ratio (INR) have been higher than expected from the imprecision of the instruments. In this study the variation of these differences was divided into subcomponents, and each of the subcomponents was estimated.

Methods: Blood samples were collected at 4 different patient visits from each of 36 outpatients who were receiving warfarin treatment and were included in the study.