Intensive FVIII replacement in haemophilia patients with hypertrophic synovium: a randomized study

Background: Hypertrophic synovium (HS) is a marker of disease activity in persons with hemophilia (PwH). Although some recommendations suggest intensifying prophylaxis in PwH with HS, no validated schedules are available. Objectives: We explored the efficacy of intensive factor VIII (FVIII) replacement treatment in PwH with HS. Methods: In a randomized, open-label study, PwH with HS were randomized to receive pharmacokinetics-driven prophylaxis targeting a FVIII trough level of 8% to 12% (intensive treatment arm [ITA]) or 3% to 5% (standard treatment arm [STA]). The primary outcome was HS reduction/resolution in the 2 treatment arms. Results: A total of 39 PwH were randomized to ITA and 36 to STA. During the study, we found a lower annual bleeding rate and a higher rate of annual bleeding rate zero in the ITA than in the STA. HS reduction/resolution was reported in 35.9% of cases in the ITA and 8.4% in the STA. In detail, in the ITA, 10.3% achieved HS reduction and 25.6% complete HS resolution, as compared to 5.6% and 2.8% in the STA. Cox regression showed that ITA was associated with HS reduction/resolution (hazard ratio: 4.75; 95% CI: 1.36-16.57; P = .014) and HS complete resolution (hazard ratio: 10.79; 95% CI: 1.38-84.45; P = .023). The analysis of the 127 joints with HS (54 elbows, 41 knees, and 32 ankles) consistently confirmed similar results. Conclusion: In this randomized study, we found a ∼5-fold higher rate of HS reduction/resolution and a ∼10-fold higher rate of HS resolution in the ITA than in the STA.