Abstract Number: PB0611
Meeting: ISTH 2021 Congress
Background: The clinical phenotype of Haemophilia A (HA) does not always correlate with the severity of HA. Similarly, the presence of inhibitors does not necessarily portend a higher bleeding-risk. This paradox between clinical and laboratory findings may be partially attributed to nongenetic modifiers like blood-group and vWF which are known to influence FVIII levels in healthy individuals.
Aims: To assess the bleeding-risk in HA patients with and without inhibitors; and the effect of blood-group and vWF on residual FVIII levels across the severity spectrum of HA.
Methods: Records of 600 consecutive HA patients attending a north-Indian tertiary centre from 2010-2020 were retrospectively reviewed. Quantitative data was compared using t-test. Categorical data was compared using chi-square test or Cochran-Armitage test for trend (as applicable). Correlations was assessed using Spearman’s correlation.
Results: Mild, moderate, and severe HA were present in 96 (16%), 246 (41%) and 258 (43%) patients, respectively. Overall, the commonest site of bleeding was intra-articular (89%). No difference in the site of bleed was noted between the three severity subgroups. Risk of spontaneous bleeding was significantly lower in mild HA (33.3%) compared to moderate (45.12%) and severe HA (47.6%, p=0.03).
Inhibitors were present in 35 (5.8%) patients. Blood-group A patients had higher odds of developing inhibitors [OR 3.02, 95% CI 1.1-8.8, p=0.04]. Patients with inhibitors had a significantly higher risk of intracranial haemorrhage compared to those without inhibitors (20% vs 4.1%, p=0.03).
No correlation was observed between vWF and residual FVIII level across the severity spectrum of HA. In mild HA, a statistically non-significant trend to higher residual levels of FVIII were seen in blood-groups A and B. No such correlation was observed in moderate or severe HA.
Conclusions: Unlike healthy individuals, vWF and blood-group does not influence residual FVIII levels across the severity spectrum of HA.
To cite this abstract in AMA style:Ray D, Kumar N, Ahluwalia J, Das R, Hans C, Jain A, Malhotra P, Bansal D. Clinicopathological Parameters and Influence of Blood Group and von Willebrand Factor (vWF) Levels on Residual Factor VIII (FVIII) Levels in Haemophilia A Patients [abstract]. Res Pract Thromb Haemost. 2021; 5 (Suppl 2). https://abstracts.isth.org/abstract/clinicopathological-parameters-and-influence-of-blood-group-and-von-willebrand-factor-vwf-levels-on-residual-factor-viii-fviii-levels-in-haemophilia-a-patients/. Accessed January 26, 2022.
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