Comparison of Short-Term Tertiary Prophylaxis at Low-Dose and Intermediate-Dose for Adults with Severe Hemophilia a in China

Background: Some studies had indicated that the joint damage progression could not be prevented by low-dose prophylaxis regimen though it had been practiced and achieved good outcomes as well as largely reduced bleedings. we initiated a retrospective study to compare the different outcomes between low-dose and intermediate-dose regimen of tertiary prophylaxis for adults with severe hemophilia A.

Methods: Data collected from the hemophilia treatment centre at Nanfang hospital from July 2010 to February 2015 ( median 2 years of follow-up), a total of 40 adult patients with severe hemophilia A (FVIII < 1%) who are receiving prophylaxis treatment≥1 year and treatment data available were eligible for enrollment in the study, including 25 patients in low-dose regimen(F‡[8-15 IU/kg 1-2times weekly or weekly<30 IU/kg), and 15 patients in intermediate-dose regimen( F‡[ 15-20 IU/kg 2-3 times weekly or weekly≥40IU/kg and <75 IU/kg). Collect the data with patients' characteristics, previous condition and treatment, treatment efficacy indexFannual bleeding rate(ABR), annual joint bleeding rate(AJBR), number of target joint, annual target joint bleeding rate, annual severe bleeding event, etc.), FVIII consumption. Use FISH scoring system to evaluate patients' joint status, use the difference between the beginning of this study and one year ago of FISH score to represent the improvement of joint function. To analyze the joint function in various subgroups(joint bleeding rate ≤5 times or >5 times) under prophylaxis treatment. Screening out patients whose dosage and frequency adherence both >75% in two groups, including 15 patients in low-dose regimen and 14 patients in intermediate-dose regimen, observed the situation that breakthrough bleeding events occurred in different time period after clotting factors' injection and calculate the proportion.

Results: 1. There were no statistical differences between two groups in age, weight, age at first bleeding, age at first treatment, family history of hemophilia and history of hepatitis. (the range of p-value was 0.221-1.000). 2. Intermediate-dose prophylaxis regimen reduced ABR than the low-dose regimen (median 13 vs. 5.5, P=0.000), as well as AJBR (median 10 vs. 4, p=0.001) and the annual target joint bleeding rate (median 8 vs. 3.5, p=0.002) .Reduced median annual absent days was found in intermediate-dose regimen group (median 7.5 vs. 0, p=0.005). In terms of total annual usages of FVIII, the intermediate-dose regimen group increased 35% than low-dose regimen group(2630 IU/kg/year vs.1950 IU/kg/year,P=0.000), but decreased 63% ABR, 60% AJBR and 56% annual target joint bleeding than low-dose regimen group. There was no statistical differences between low-dose and intermediate-dose groups in terms of target joint numbers (median 1 vs.1,P=0.579) and annual severe bleeding events(median 0 vs.0, P=0.911). 3. There was statistical differences between two groups on the improvement of FISH(P=0.008). The proportion that patients' annual joint bleeding rate ≤5 in low dose and intermediate-dose group were 12% and 73.3%. When AJBR ≤5, the mean improvement of Fish score of low-dose and intermediate-dose group was 0.33 and 1.18, When AJBR>5, the mean score was -0.09 and 1.00 respectively, while the joint function still improved in intermediate-dose group.3. The low-dose group had higher proportion of breakthrough bleeding in 24-48h after FVIII injection (median 45.5% vs.27.95%, P=0.000), while intermediate-dose group got higher proportion in more than 48h after FVIII injection (median 60% vs.43.75%,P=0.001).

Conclusion: 1. Compared to low-dose prophylaxis regimen, the ABR, AJBR, annual target joint bleeding rate, annual absent days and joint functionwere significantly decreased in patients treated with intermediate-dose regimen.2. It is indicated the intermediate-dose prophylaxis treatment would be better in long-term effect than low-dose regimenin improving joint function. 3. The low-dose group had higher proportion of breakthrough bleeding in 24-48h after FVIII injection, while intermediate-dose group got higher proportion in more than 48h after FVIII injection. Once every other day regimen is beneficial to further reduce bleedings in intermediate-dose prophylaxis treatment.