Evaluation of a commercial set of frozen plasmas for instrument‐to‐instrument comparability

Abstract

Introduction To perform comparability of instruments, the laboratory can select patient samples spanning the reportable range or can use plasma sets from commercial suppliers. We evaluated ExpertCor Routine (ECR) plasma set (Stago), a set of frozen plasmas enabling to verify the agreement between different coagulation analysers. Additionally, we evaluated whether the concept of transference of the reference range is acceptable between instruments, once comparability between the instruments is approved. Methods Patient samples and the ECR plasma set were evaluated for method comparison for prothrombin time, activated partial thromboplastin time and fibrinogen on five instruments. Results of one instrument were compared to the mean of all analysers by Passing‐Bablok regression and Bland‐Altman analysis. Reference ranges were checked on all instruments. Results The %mean difference was ≤5% and ≤3.7% for all analyser/parameter combinations, for ECR and patient sample data sets, respectively. All predefined criteria to fulfil good comparability between instruments were met. The between‐instrument comparison with the ECR plasma set and the patient samples was equal for PT, INR and fibrinogen. After demonstrating comparability between instruments by either of the two plasma sample sets, reference ranges can be used interchangeably between identical instruments. Conclusion Instrument‐to‐instrument reproducibility showed comparable results using a data set obtained with patient samples or a commercial plasma set. Once comparability between instruments is confirmed, defined reference ranges can be transferred from one instrument to the other instrument without additional testing. The ECR plasma set is a good alternative to the use of local patient samples to evaluate instrument comparability.

Commercial human frozen plasmas for local, cross-site and long-term comparability of coagulation analysers

“…Our study confirms the use of routine ECR sets for correlations between instruments, as previously demonstrated in the study of De Sloovere and Devreese [2], who find coefficient correlation at least 0.988 for PT and INR and at least 0.981 for aPTT and fibrinogen and all correlation slope between 0.9 and 1. The strength of our study was that the inter-instrument correlation was checked on two different laboratories at the same time to evaluate inter-laboratory agreement.…”

“…This set of plasmas has been evaluated by a Belgian coagulation laboratory for instrument-to-instrument comparison of four routine coagulation parameters (PT, INR, aPTT and fibrinogen) and they have demonstrated that this plasma set is a good alternative to the use of patient samples. The goal of our study was to corroborate those results and expand it to other coagulation parameters [2]. Accreditation requirement applies not only for correlations between instruments but also for inter-site agreement.…”