The Clinical Associations and Outcomes of Patients Admitted with Acquired Hemophilia; A Review of the 2012 National Inpatient Sample

Background: Sporadic cases of acquired hemophilia are exceedingly rare, with limited data on the disease incidence, clinical associations, and mortality, particularly in hospitalized patients. The aim of this study is to evaluate the epidemiology and mortality of patients hospitalized with acquired hemophilia from a large national database. Methods: Using the 2012 National Inpatient Sample (NIS), admissions with an International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9-CM) codes for Acquired hemophilia (286.52) were extracted. Any patient with a concomitant diagnosis of congenital hemophilia was excluded for quality control. Admission data was extracted and correlated with associated clinical diagnosis, age, gender, length of stay and mortality. Results: Of the 7,296,968 unweighted admissions in the 2012 NIS, 80 admissions met the inclusion criteria (incidence of 0.00001%). Patients admitted with acquired hemophilia tended to be older (mean age 63.6 years, SD 18.7) & male (55%). Admissions were most commonly unplanned (88.7%), lengthy, (mean 8.45 days, SD 7.4 days), and costly (mean charge $280,730.00 USD, SD $617,293 USD). Inpatient mortality was rare (N=3, 3.75%). Packed red cell transfusion, as well as coagulation factor transfusions was common (42.5% and 20% respectively). Admissions involving critical illness were relatively common as well (22.5% with acute renal failure, 10% receiving mechanical ventilation). 30% of patients admitted with acquired hemophilia had an active or previous malignancy diagnosis (the most common being leukemia N=4, breast cancer N=3, and prostate cancer N=3). 50% of admissions were associated with an acute or chronic infectious disease (the most common being viral hepatitis N=10, bacterial infections N=9, and pneumonia N=9). When compared to patients admitted with hemophilia A (N=1645), those with acquired hemophilia were significantly older (mean age 63.6 vs 41.2 years p<0.001 ), had longer lengths of stay (8.45 vs. 5.56 days p<0.001 ), incurred higher mean charges (280,730.34 vs 139,458.90 USD p<0.001 ), and were more likely to have unplanned admission (88.7 vs 77.9% p=0.01, OR 2.2, 95%CI 1.1-4.4). Admissions involving acquired hemophilia were more likely to have an associated bleeding event then those for patients with hemophilia A (43.75% vs. 32.34% p= 0.03, OR 1.6, 95%CI 1.0-2.5 ), and involve transfusion of packed red blood cells (42.5% vs. 8.62% p<0.001, OR 8.2, 95%CI 5.0-13.2 ). Malignancy was also significantly more common in acquired hemophilia admissions as compared to hemophilia A (30% vs. 11.67 p= *<0.001, OR 3.24, 95%CI 1.9-5.3), as were rheumatologic disorders (12.5% vs 3.3%, p=0.006, OR 4.129, 95%CI 2.0-8.4). Rates of total active infections were not significantly different, even after controlling for HIV and Hepatitis C. Due to the limitations of the database, pregnancy associations could not accurately be assessed. Inpatient mortality was not significantly different between the two groups. Conclusions: Acquired hemophilia is a rare disorder, particularly as an inpatient diagnosis. Admitted patients with acquired hemophilia tend to be older, and have lengthy hospitalizations incurring a high cost. Transfusion of blood products and coagulation factors were relatively common, as was critical illness. Associated infections were quite common, associated with 50% of admissions, as was a diagnosis of cancer occurring in 30% of admissions. Regardless of this, mortality remained low at 3.75%. Compared with patients admitted with hemophilia A, those with acquired hemophilia were more likely to have significant bleeding requiring transfusion, and have an associated malignancy. Mortality was low in both groups and not significantly different. Disclosures Recht: Novo Nordisk: Research Funding; Baxalta: Research Funding; Biogen: Research Funding; Kedrion: Membership on an entity's Board of Directors or advisory committees. Taylor: Baxalta: Consultancy, Research Funding; Novo Nordisk: Research Funding; Kedrion: Consultancy, Research Funding; Biogen: Consultancy, Research Funding.