A Multicentric Verification of Hereditary and Acquired Thrombophilia Coagulation Assays

Aims: With an ever-growing number of patients being admitted to our University Hospital Sveti Duh (Zagreb, Croatia), there was a need to positively respond to clinicians' demands about hereditary and acquired thrombophilia testing.

Study Design: An extensive and multicentric verification of coagulation assays included in thrombophilia testing was performed on the BCS XP coagulation analyzer (Siemens Healthineers, Marburg, Germany): antithrombin activity (AT) (Innovance Antithrombin), protein C activity (PC) (Berichrom Protein C), protein S activity (PS) (Protein S Ac), free protein S antigen (free PS:Ag) (Innovance Free PS Ag), activated protein C resistance (APCR) (ProC Ac R and ProC Global + Coagulation Factor V Deficient Plasma), lupus anticoagulant (LA) screening (LA1 and activated partial thromboplastin time by using Dade Actin FSL as reagent) and confirmation test (LA2), factor VIII activity (FVIII) (Dade Actin FS and coagulation FVIII Deficient Plasma).

Place and Duration of Study: Department of Medical Laboratory Diagnostics, University Hospital Sveti Duh, Zagreb, Croatia, between January 2020 and December 2021.

Methodology: Verification protocol included: the precision study (CLSI EP15-A3 protocol), trueness estimation by comparison of seventy remnant plasma samples with two large Croatian hospital laboratories with established thrombophilia testing, and verification of reference intervals and cut-off values (CLSI EP28-A3C and CLSI HA-60 guidelines).

Results: All of the obtained imprecision CVs were within the manufacturer's claims (<5/10/15%). While the observed bias for PC (+1.9%) was within the EFLM performance specifications (6.7%), the average bias for AT was higher than acceptance criteria (+10.8% vs 3.2% allowed). P&B regression revealed a significant positive proportional difference (slope=1.14). Comparison of PS activity yielded a high negative bias (-33.4%) that exceeded the acceptance criteria of 8.1%. Regarding LA testing, the diagnostic accuracy was 99% when compared to Sestre milosrdnice UHC (N=70) and 95% when compared to University Hospital Centre Zagreb (N=19). All manufacturer's reference intervals and cut-offs were verified.

Conclusion: The verification study confirmed all manufacturer's claims, except for PS which has been replaced with free PS:Ag determinations.