Background: Relationship between PK parameters and imaging examination scores were not reported before.

Aims: To investigate the relationship between individual PK profiles and bleeds or imaging scores in Chinese boys with severe hemophilia A.

Methods: Thirty-five boys with severe hemophilia A were enrolled in Beijing Children’s Hospital in 2018. After a wash-out period of 72 hours and a single FVIII infusion of 50IU/kg, blood samples were collected and tested at five time points for PK assessment. Trough level and time below 1IU/dL weekly were generated by WAPPS-Hemo. X-ray, ultrasound and MRI were used to check the both sides of knees, elbows and ankles in the form of Pettersson, HEAD-US and IPSG MRI scores. Baseline and bleeding details were collected.

Results: Twenty-one boys kept trough FVIII level above 1IU/dL in daily prophylaxis. Compared with those with lower trough level (< 1IU/dL), patients in higher trough FVIII level group (>1IU/dL) had fewer bleedings (ABR:3 vs 5, P< 0.05; AJBR: 1 vs 2, P< 0.05 ), lower Pettersson score
(0 vs 2, P< 0.05), HEAD-US score (1.5 vs. 3, P< 0.05) and HJHS scores (1.5 vs. 4, P< 0.05). Time below 1IU/dL weekly was correlated with ABR (r=0.69, P< 0.01), AJBR (r=0.64, P< 0.01),MRI scores (r=0.54, P< 0.05) US scores (r=0.50, P< 0.05), X-ray scores (r-0.49, P< 0.05) and HJHS scores (r=0.47, P< 0.05). In addition, US score had a good relationship with X-ray scores
(r=0.78, P< 0.001), MRI scores (r=0.92, P< 0.001) and HJHS score (r=0.57, P< 0.001).

Conclusions: Patients with longer time spent below a trough FVIII level of 1IU/dL bleed more and had higher imaging and HJHS scores. The US has good relationship with X-ray, MRI and HJHS scores and has potential to be used in hemophilia patients’ daily examinations.

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ISTH Congress Abstracts - https://abstracts.isth.org/abstract/bleeds-and-imaging-scores-in-relation-to-pharmacokinetics-of-coagulation-factor-viii-in-chinese-pediatric-patients-with-severe-hemophilia-a/