ABSTRACT
INTRODUCTION: Inhibitor formation is a major complication of hemophilia treatment because it interferes with the clinical response to factor replacement and causes significant morbidity. This cross-sectional study was conducted to assess the presence and frequency of inhibitors among registered person with hemophilia and to identify risk factors associated with inhibitor development. PATIENTS AND METHODS: A total of 143 hemophilics, 118 with hemophilia A (HA) and 25 with hemophilia B (HB), were enrolled for the study. Participant's clinical data were obtained through patient's medical records. Factor VIII and IX levels and the presence of inhibitors were assessed using a fully automated coagulometer. From the results of a Bethesda assay, patients were divided into those with high titers (≥5 BU) and those with low titers (<5 BU). RESULTS: The patient's age ranged from 1 to 67 years with median of 13.8 years. Inhibitors were detected in 18.6% and none of HA and HB patients, respectively. Of the 22 patients with HA and inhibitors, 18 (82%) had high titer inhibitors. The frequency of inhibitors was significantly higher among patients with severe hemophilia, a history of early exposure (≤3 months) to factor VIII concentrate, and family histories of autoimmune disease and immune system challenges (P < 0.05). The independent risk factors associated with inhibitor development were severe hemophilia (95% CIs = 1.02-55.6, OR = 7.5) and immune system challenges (95% CIs = 1.14-5.99, OR = 2.6). CONCLUSION: Inhibitors were common among HA patients, and both severe HA and immune system challenges (surgery and trauma) are independent risk factors for inhibitor development.