PB1258 - Discrepancies Between Laboratory Assays In Hemophilia A Pediatric Patients Receiving Prophylaxis

Tuesday, June 27, 2023

18:30 – 19:30 ET

Room: Exhibition

Co-Author(s)

AA

Alkistis Adramerina, MD Msc

Consultant
1st Pediatric Department Aristotle University of Thessaloniki, Greece
Thessaloniki, Thessaloniki, Greece

Presenting Author(s)

Aikaterini Teli, MD, PhD

Consultant
1st Pediatric Department Aristotle University of Thessaloniki, Greece
Thessaloniki, Thessaloniki, Greece

Co-Author(s)

Maria Vousvouki, Master of Science (she/her/hers)

Consultant
1st Pediatric Department Aristotle University of Thessaloniki, Greece
Thessaloniki, Thessaloniki, Greece
AE

Athina Efstathiou

Medical Student
1st Pediatric Department, School of Medicine, Faculty of Health Sciences, Aristotle University of Thessaloniki, Greece
Thessaloniki, Thessaloniki, Greece
SS

Symeon Symeonidis

Scientific Associate
1st Pediatric Department, School of Medicine, Faculty of Health Sciences, Aristotle University of Thessaloniki, Greece
Thessaloniki, Thessaloniki, Greece
AT

Antigoni Theodoridou

Hemophilia Nurse
1st Pediatric Department, School of Medicine, Faculty of Health Sciences, Aristotle University of Thessaloniki, Greece
Thessaloniki, Thessaloniki, Greece
SG

Spyros Gerou

Biopathologist
"Analysis" Lab
Thessaloniki, Thessaloniki, Greece
ME

Marina Economou

Professor of Pediatrics-Pediatric Haematology
1st Pediatric Department Aristotle University of Thessaloniki, Greece
Thessaloniki, Thessaloniki, Greece

Background: Monitoring of prophylaxis in hemophilia requires measurements of accepted accuracy and precision. The one-stage clotting assay (OSA) is inexpensive and, using certain reagents, recommended for most recombinant products, whereas chromogenic substrate assay (CSA) is considered more sensitive at low factor levels.

Aims: To assess discrepancies in FVIII:C measurements in hemophilia A patients on prophylaxis in the routine clinical setting.

Methods: Demographic data, FVIII product and random post infusion FVIII:C measurements were recorded in 24 pediatric patients. FVIII:C levels were measured using both OSA Pathromtin SL (DADE Behring) and CSA (Siemens).

Results: In total, 121 samples were tested. Mean patient age was 10.6 (3-18) years. Out of 24 patients, 13 (54%) were on EHLs and 11 (46%) on SHLs. Mean sample collection time was 35.8 hours post infusion (31.9 and 40 hours for SHLs and EHLs, respectively).
With regards to SHLs, in the 67 collected samples mean CSA/OSA ratio was 1.3. Discrepancy of >30% was found in 14 (21%) samples, all in moderate/severe FVIII:C deficiency. Statistical correlation was found between collection time and CSA/OSA ratio, as well as percentage of discrepancy (r=0.45 P 0.002 and r=0.44 P0.0004).
In 54 EHL samples mean CSA/OSA ratio was 1.47. Discrepancy of >30% was found in 33 (66.7%) samples: 16 (48.5%) of moderate/severe FVIII:C deficiency and 17 (51.5%) of mild deficiency. No correlation was found between collection time and CSA/OSA ratio or percentage of discrepancy (r=0.08 P 0.24, r=0.218 P 0.11).
FVIII:C levels discrepancies >30% following different SHLs and EHLs are listed in Table 1.

Conclusion(s): Measurement of FVIII:C with OSA and CSA resulted in significant discrepancies, mainly with EHLs, however, without reaching statistical significance. Systematic report of discrepancies should prompt development of general guidelines.