Bleeds and resource use in hemophilia B: retrospective observational study.

To describe people with hemophilia B (PWHB) in the US who experience bleeds despite factor replacement therapy and to quantify the associated burden from the third-party payer perspective. Observational study of adult male PWHB treated with factor IX replacement therapy identified from the PharMetrics Plus claims data from 2010 to 2019. Patients with medically recorded bleeds (MRBs) were identified using diagnostic codes. Rates and rate ratios of inpatient admissions, emergency department (ED) visits, and outpatient visits among PWHB with and without MRBs were estimated. The presence of comorbidities was identified using diagnostic codes, and the analysis was stratified by age group. There were 345 PWHB with MRBs and 252 without MRBs. More than half of PWHB with MRBs (56.8%) had 1 or more comorbidity vs 39.3% of PWHB without MRBs. The prevalence of anxiety and depression was high in PWHB, regardless of bleed status and age group, whereas the prevalence of other comorbidities increased with age group. The rate of all-cause inpatient admissions for PWHB with MRBs was 14.8 per 100 person-years (95% CI, 12.8-17.1), 2.5 times higher than for PWHB without MRBs. The rate of all-cause ED visits for PWHB with MRBs was 67.6 per 100 person-years (95% CI, 63.2-72.3), 2.7 times higher than for those without MRBs. This study reports significant resource use and clinical burden among PWHB who seek medical care. PWHB with MRBs had considerable all-cause resource use compared with PWHB without MRBs. The prevalence of mental illness was consistently high across all age groups.