OBJECTIVES Aimed to identify the factors associated with bleeding in hemophilia A patients in Korea.

METHODS Data for this analysis is from a cross-sectional and observational study that has been conducting at 9hospitals from April2018 and continuing to Sep2019. 318(51.3%)of total target patients of the study were included in this interim analysis. Patients diagnosed with hemophilia A, aged≥16years, injected clotting factor concentrates by themselves or patients’ legal guardians, and continued treatment for ≥1month during the study period were subjected. Patients’ characteristics and treatment patterns were considered as potential factors. The definition of bleeding was defined as follows; mild bleeding-did not require supplementation of deficient coagulation factor; moderate bleeding-was not an emergency, required supplementation of the clotting factors; severe-life threatening bleeding which requires immediate, intensive clotting factor supplementation.

RESULTS The mean age of 318patients was 32.6years and 99.4% were male. Mean duration of disease was 272.7months. 88.4% of patients were severe hemophilia A, 73.6% had arthropathy, and 1% had antibody. Total duration of treatment was mean102.6months. Treatments were prescribed as maintenance for 65.7% of the patients and on-demand for 26.1%. Types of reconstitution device of both-sides adapter were used in 81.1% and prefilled syringes were used in 6.3% patients. Mean treatment dosage was 1924.5IU/kg. Clotting factors were prescribed for ≥2/week injections in 66.7% and for ≤2/month injections for 12.6%of patients. 160(50.3%)patients had experienced bleedings, of which 158patients experienced mild and 2patients experienced moderate bleedings. Among the factors, maintenance treatment group reduced bleeding episodes compared to mixed group of maintenance and on-demand treatment(OR=0.03,P<0.0001). And bleeding episodes were more frequent in the ≥2/week usage group compared to ≤2/month usage group.

CONCLUSIONS The maintenance treatment reduced bleeding in hemophilia A patients. And more frequent injections of clotting factor concentrates for hemostasis reflected disease severity. Those factors should be taken into account in treatment strategies under real world setting.