What evidence is there to support the FVIII and FIX targets in the guidelines around the time of surgery?¶
Answer: The evidence is weak. Perioperative FVIII and FIX targets rest on product labeling, consensus guidelines, pharmacokinetics, and a small body of observational/PK studies rather than controlled trials.
- Nordic Hemophilia Guidelines — for major surgery, recommend peak targets of 70–100 IU/dL, with trough targets of 70 IU/dL (days 1–3), 50 IU/dL (days 4–6), and 30 IU/dL (days 7–9); minor surgery target is 50 IU/dL. These targets were validated in a Nordic real-world evidence study of surgeries under extended half-life rFVIIIFc/rFIXFc (the source below).
- Weight-based dosing overshoots — in mild hemophilia A, current weight-based perioperative dosing frequently produces FVIII levels above target (Schütte et al., 2019), further supporting PK-guided dosing in the postoperative setting to reduce overexposure and adverse effects.