Perioperative Outcomes Associated with Inhibitor Status in Patients with Hemophilia - a Retrospective Cohort Study

Background The development of antibodies (inhibitors) to clotting factors compromises the treatment of people with Hemophilia A (HA) and B (HB), and results in ineffective clotting-factor therapy, higher risk of complications, and need for bypassing agents to achieve hemostatic control. Objectives To evaluate the association between presence of inhibitors and peri-operative hemostatic control, complications, and deviations from pre-surgery plans. Methods We conducted a retrospective study using data from the Indiana Hemophilia and Thrombosis Center (IHTC) surgical database (1998 - 2019). Association between specified outcomes and inhibitor status at surgery was assessed using generalized linear models while controlling for patient and procedural characteristics. Results A total of 1,492 surgeries were conducted in 539 patients with HA or HB, 4.8%(72/1492) of which were conducted in 20 (15 HA; 5HB) patients with inhibitors. Of the 72 surgeries involving inhibitors, 30 were high-titer, 10 low-titer and 32 with unreported inhibitor titers. Adjusting for patient's age, hemophilia diagnosis, surgery setting, and surgery type, the risk of achieving perioperative hemostasis was lower in surgeries involving inhibitors compared to non-inhibitor surgeries (65.6% vs 91.4%; aRR=0.78; 95% CI= 0.61-0.99; p=0.038). Complications including hemorrhage, fever, pain, thrombosis, and infections occurred more frequently in surgeries involving inhibitors (31.7% vs 14.6%; aRR= 1.67, 95% CI= 1.07 - 2.63; p=0.025). Deviation from pre-surgical plans, usually due to the development of complications including lack of effective hemostatic control, also occurred more frequently in surgeries involving inhibitors compared to those without inhibitors (70.8 vs 39.5%; aRR= 1.63, 95% CI= 1.33 - 2.01; p