Mis-identification of factor inhibitors by diagnostic haemostasis laboratories: recognition of pitfalls and elucidation of strategies. A follow up to a large multicentre evaluation.
OBJECTIVE
We previously reported the ability of diagnostic haemostasis facilities to identify coagulation factor abnormalities and inhibitors, through a large multi-centre study conducted on behalf of the Royal College of Pathologists of Australasia (RCPA) Quality Assurance Program (QAP). In the current report, additional data evaluation aims to (1) help identify the reasons behind the failures in inhibitor identification, (2) highlight the pitfalls in inhibitor testing, and (3) help elucidate some strategies for overcoming these problems and to assist in better identification and characterisation of inhibitors.


METHODS
Forty-two laboratories blind tested a set of eight samples for the presence or absence of inhibitors. These included true factor inhibitors (FVIII and FV), and other samples that reflected potential pre-analytical variables (e.g., heparin contamination, serum, EDTA plasma, aged plasma) that might arise and complicate inhibitor detection or lead to false inhibitor identification.


RESULTS
There was a wide scatter of inhibitor results, with false positive and false negative inhibitor identification, and mis-identification of inhibitors (e.g., FVIII inhibitor identified where FV inhibitor present). Further analysis of the pattern of reported laboratory results, including routine coagulation testing and factor profiles, allowed some additional interpretative power to provide strategies that will assist laboratories to improve the accuracy of inhibitor identification in the future.


CONCLUSIONS
There are currently occasional lapses in factor inhibitor identification, which this report will hopefully help address.
Favaloro
Emmanuel J
EJ
Department of Haematology and Royal College of Pathologists of Australasia Quality Assurance Program, Institute of Clinical Pathology and Medical Research, Westmead Hospital, New South Wales 2145, Australia. emmanuel@icpmr.wsahs.nsw.gov.au
Bonar
Roslyn
R
Duncan
Elizabeth
E
Earl
Gail
G
Low
Joyce
J
Aboud
Margaret
M
Just
Sarah
S
Sioufi
John
J
Street
Alison
A
Marsden
Katherine
K
D001778:Blood Coagulation Disorders / Q000175:diagnosis*; D001779:Blood Coagulation Factors / Q000037:antagonists & inhibitors*; D001780:Blood Coagulation Tests / Q000592:standards*; D019411:Clinical Laboratory Techniques / Q000592:standards*; D003951:Diagnostic Errors; D005188:False Negative Reactions; D005189:False Positive Reactions; D006801:Humans; D011785:Quality Assurance, Health Care / Q000592:standards; D011786:Quality Control; D015203:Reproducibility of Results
D001779:Blood Coagulation Factors