Victor Jimenez‐Yuste

Introduction Tailored prophylaxis is the current treatment regimen for patients with severe haemophilia A. Recently, published guidelines describe two possible approaches, based on clinical characteristics or estimation of pharmacokinetic parameters. However, both have strengths and weaknesses, and their characteristics need to be integrated to optimize treatment appropriately. In this paper, we present a model that considers together the characteristics of prophylaxis and the relevance of each. Methods The age at initiation of prophylaxis, number of bleeding events, treatment regimen, therapeutic adherence, FVIII trough levels, and joint status were analyzed in 59 patients followed at La Paz University Hospital between January 2000 and December 2019. Results The mean duration of primary prophylaxis of 113.37 ± 57.79 months. Eighty‐three percent ( n = 49) had no joint status involvement at the end of follow‐up (HJHS and HEAD‐US = 0). The median ABR was 0.7 (IQR 0.2 –1.0) and 54.2% presented trough levels of FVIII during follow‐up >1 IU/dL. 72,9% engaged in some type of physical activity and overall adherence was over 85% in all patients evaluated. The regression analysis performed, considering all these factors, showed that the initiation of prophylaxis before 21 months of age was the most relevant protective factor against the appearance of joint involvement (OR 88.33 p .031 CI 95% 1.49‐5224.40) Conclusion Early initiation of prophylaxis was the most relevant factor in the protection of joint status. More comprehensive analysis models adapted to the characteristics of each population, are needed to adequately individualize treatment.