Factor VIII Dose Should Consider Both Body Weight and Fat Mass

For those with hemophilia A, dose calculation should be individually adapted to under-/overweight patients

MONDAY, July 18 (HealthDay News) -- For patients with hemophilia A, an infusion dose of factor VIII (FVIII) should be modified according to the patient's body weight (BW) and fat mass index (FMI), and should be adapted for over or underweight patients, according to a study published online July 5 in the Journal of Thrombosis and Haemostasis.

Séverine Henrard, from the Université Catholique de Louvain in Brussels, Belgium, and colleagues investigated the inter-individual variability of FVIII recovery and its dependence on morphometrical variables including BW, FMI, body mass index, and the difference between actual and ideal BW. FVIII was evaluated in 46 non-actively bleeding patients with hemophilia A who were already being treated with a recombinant FVIII concentrate. Morphometrical predictors of recovery were identified by regression trees.

The investigators found that the median recovery was 2.08, 2.63, and 1.87 for all patients, for those with a BW of 81 kg or more, and for others, respectively. A significantly higher recovery was seen in patients with an FMI of 20 percent or more, compared to those with an FMI of less than 15 percent (median recovery, 2.35 versus 1.74). Based on regression trees the median recovery for three groups was identified: BW and FMI of less than 80.5 kg and 22.3 percent, respectively, 1.80; a BW of less than 80.5 kg and FMI of 22.3 percent or more, 2.16; and a BW of 80.5 kg or more, 2.63.

"FVIII dosing should take into account patient BW and FMI, and it must be individually adapted to underweight or overweight patients. However, a FVIII recovery value of 2 can be used for normal BW patients with an FMI in the range of 15 to 20 percent," the authors write.

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