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Assay discrepancy in mild haemophilia A: entire population study in a National Haemophilia Centre
Author(s) -
POULSEN A. L.,
PEDERSEN L. H.,
HVAS A.M.,
POULSEN L. H.,
THYKJÆR H.,
INGERSLEV J.
Publication year - 2009
Publication title -
haemophilia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.213
H-Index - 92
eISSN - 1365-2516
pISSN - 1351-8216
DOI - 10.1111/j.1365-2516.2008.01899.x
Subject(s) - haemophilia , haemophilia a , medicine , chromogenic , population , haemophilia b , pediatrics , gastroenterology , art , environmental health , visual arts
Summary. Assay discrepancy in mild haemophilia, here defined by a significantly higher factor VIII (FVIII):C response by the one‐stage procoagulant assay as compared with a two‐stage enzymatic method, has repeatedly been reported in literature. The purpose of this study was to determine the overall prevalence of this phenomenon amongst mild haemophilia families from a population of 2.95 million inhabitants in the Western Danish region. Information was collected retrospectively through a thorough search of archives of the National Haemophilia Centre in Aarhus. We identified 109 patients with mild haemophilia A amongst whom 92 were eligible to enter the study. These represent a total of 53 unrelated families. Our data illustrate that this assay discrepancy pattern is found quite frequently amongst our mild haemophilia A families. While the ratio of FVIII:C chromogenic/FVIII:C clot values was quite consistent amongst patients belonging to same family pattern, ratios in the entire cohort of families ranged from 0.18 to 1.00. Selecting a cut‐off level for the FVIII:C chromogenic/FVIII:C clot ratios at 0.7, 0.6 and 0.5, respectively, we found that 38 (72%), 27 (51%) and 19 (36%) of families, respectively, displayed this assay discrepancy. In 10 patients, the FVIII:C chromogenic level was inside the category of moderate haemophilia at >0.01–<0.05 IU mL −1 , pointing to a class‐shift in the biochemical phenotype. In conclusion, our data illustrate a substantial prevalence of the assay discrepancy phenomenon amongst mild haemophilia A patients in our geographical area.