OBJECTIVES: Determine the economic impact and resource utilization of adult HIV and HCV co-infected hemophilia patients in a managed care population in the United States. METHODS: Retrospective claims database analysis from 1/97 to 4/04. Patients continuously enrolled for at least 6 months and > 18 years of age were included. Hemophilia patients were identified using ICD-9CM, HCPCS, and NDC codes. Four cohorts for analysis were established: Hemophilia only Hemophilia+HIV, Hemophilia+HCV, Hemophilia+HIV+HCV. The main outcomes of study were costs associated with all pharmacy and medical claims, inpatient hospitalizations (frequency and length of stay) and office visit distribution by physician specialty. RESULTS: Annual cost of care was $85,616 for the hemophilia only cohort, $99,180 for the HIV cohort, $105,676 for the HCV cohort and $129,889 for HIV/HCV co-infected cohort in 2004 dollars. Clotting factor accounted for approximately 70-81% of total costs. The Hemophilia only, HCV, HIV, HIV/HCV infected hemophilia cohorts had prescription drug costs of $2,341, $8,867, $6,256 and $12,060, respectively. Approximately 17% of hemophilia only, 19% of HCV, and 27% of the HIV/HCV cohorts were hospitalized during the study period (p=0.45). Hospitalizations that were hemophilia related accounted for 43% of total hospitalizations for the hemophilia only cohort and 16% for the HIV/HCV cohort (p=0.30). No significant difference in inpatient length of stay was found. There was a difference in the mean number of office visits among the cohorts (p=0.022) with the HIV/HCV cohort having more visits than the hemophilia only group, 18.3 vs. 7.3, respectively (p=0.05). CONCLUSION: Although we were not able to control for severity, the presence of HIV and HCV co-infection in hemophiliacs is associated with an increase in annual costs by up to 52%. Increased clotting factor use and prescription drug costs in the virally infected groups account for most of the increase in costs.