Methods
We collected prospective and retrospective data from patients with
haemophilia B (FIX activity level ≤5 IU/dL) treated with rFIX-Fc and
included in the OPTI-CLOT TARGET study (NTR7523) or United Kingdom
(UK)-EHL Outcome Registry (NCT02938156). Predictive performance was
assessed by comparing predicted with observed FIX activity levels. A
novel population PK model was constructed using nonlinear mixed-effects
modelling.