Researchers revealed several factors, including plasma factor levels, bleed history, and physical activity, as risk factors for bleeding in people with hemophilia, as published in the Journal of Thrombosis Haemostasis.

They found no clear risk assessment model (RAM) but noted that additional factors, such as obesity and antithrombotic treatment, should also be investigated.

“The identification of patients at high risk of bleeding is an important first step in lowering the risk of bleeding,” the authors wrote. “Factor levels, physical activity, and bleeding history appear to be the most important risk factors to be included in such a model. However, these data are not conclusive, and the role of other risk factors should also be explored.”

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The research team performed a systematic literature review of risk factors for bleeding and RAMs. The primary outcome was any bleeding episode among outpatients who were treated with a clotting factor. Eleven studies were identified; however, due to the heterogeneity of the risk factor types and outcomes, measurement methods, and risk estimates, quantitative synthesis was not possible and the authors provided a narrative synthesis of the results.

Ten of the 11 studies reported that higher plasma factor levels were associated with lower bleeding risk, even across varying techniques used to estimate these levels and incorporating indirect measures such as treatment frequency and adherence.

Bleeding history was also found to have a strong association with a higher risk of bleeding. Other factors, such as age, body mass index, laboratory tests, the season of the year, and antithrombotic treatment, were only assessed in 1 study each. The authors noted that more high-quality studies are required, with more clearly defined predictors and outcomes, to develop a reliable RAM for estimating the risk of bleeding in people with hemophilia.


Germini F, Noronha N, Abrahan Philip B, et al. Risk factors for bleeding in people living with hemophilia A and B treated with regular prophylaxis: a systematic review of the literatureJ of Thrombosis Haemost. Published online April 23, 2022. doi:10.1111/JTH.15723