Frequent but low titre factor VIII inhibitors in haemophilia A patients treated with high purity concentrates

The development of inhibitor antibodies is one of the more important compli cations in the management of haemophilia patients. In a previous study, the prevalence of inhibitor varies between 5 and 52%, seems to be different fo r different types of concentrates, and is less frequent in multitransfused patients. In our prospective study we followed for 3 years 62 multitransfus ed haemophilia patients without inhibitor or past history of inhibitor. Thi rty-seven haemophilia patients were treated with intermediate purity factor VIII concentrates, whereas 25 were given high purity concentrates (from th e eighth month of the study five of these patients were treated with recomb inant products). Factor VIII inhibitor antibody developed in seven of 25 ha emophilia patients treated with high purity concentrates or recombinant pro ducts, whereas none of the haemophilia patients treated with intermediate p urity concentrates had inhibitors. The difference was statistically signifi cant (P < 0.001; OR = 0.06, 95% CI 0.001-0.3). In all patients, the titre o f the inhibitor was low and no problem occurred in their management. Since inhibitors appeared in multitransfused patients when transfused with high p urity concentrates and/or when the patients were switched to recombinant FV III product, the development of inhibitor seems to be due to the administra tion of a new concentrate. Therefore this potential complication must be co nsidered every time a new concentrate is administered, Blood Coag Fibrinol 10:117-120 (C) 1999 Lippincott Williams & Wilkins.