Weight-based Dosing in Hemophilia A

Hemophilia A is an inherited (genetic) disease where a protein, factor VIII (FVIII), which promotes blood clotting is missing or does not work properly. Individuals with hemophilia A are at risk for bleeding. Bleeding is prevented and/or treated with recombinant factor VIII (rFVIII), which is an FDA-approved treatment for Hemophilia A. Obesity is common among patients with hemophilia. Some studies have shown that obese hemophilia patients may be able to prevent bleeding with a lower dose of clotting factor than the dose they are currently receiving. The lower dose is calculated based on what a patient should weigh rather than what he does weigh. This is a clinical research study to test whether calculating rFVIII dosing based on lean body mass and ideal body weight (what a person should weigh based on his height) in overweight and obese patients with hemophilia is more accurate than calculating rFVIII dosing based on what a person actually weighs.