Frequency of specific coagulation inhibitors and antiphospholipid antibodies in Tunisian haemophiliacs

Production of factor VIII or factor IX inhibitors is a major complication limiting the efficiency of substitutive therapy in haemophiliacs. Moreover, viral infections, the second serious complication of replacement therapy, may be associated to the occurrence of antiphospholipid antibodies which paradoxically lead to thrombosis. We investigated the prevalence of coagulation inhibitors (factor VIII and factor IX inhibitors, antiphospholipid antibodies) in Tunisian haemophiliacs, and we assessed concomitant coagulation factor deficiencies. Thirty-two previously treated haemophiliacs (20 haemophiliacs A; 12 haemophiliacs B) were screened for factor VIII and factor IX inhibitors by APTT mixing study, Bethesda test and modified Nijmegen method, and investigated for the presence of anticardiolipin, anti-β2 glycoprotein I, lupus anticoagulant and associated coagulation factors deficiencies. The frequency of factor VIII and factor IX inhibitors was low (5%) in contrast to the high prevalence of antiphospholipid antibodies (28.1%). Four and nine patients were positive for anticardiolipin and anti-β2 glycoprotein I, respectively. No lupus anticoagulant was detected. The prevalence of antiphospholipid antibodies was higher in patients with positive hepatitis C virus infection serology as compared to patients with negative serology (41.6% vs. 20%). Concomitant factor VII and/or factor V deficiency was found in 10 patients. In conclusion, the occurrence of factor VIII and factor IX inhibitors is rare among Tunisian haemophiliacs. The clinical relevance of antiphospholipid antibodies requires further investigations. We emphasize the importance of screening for concomitant deficiencies in haemophiliacs when the clinical presentation is suggestive.