Incidence of factor VIII inhibitors throughout life in severe hemophilia A in the United Kingdom

Hay, Charles R M, Palmer, Ben, Chalmers, Elizabeth, Liesner, Ri, Maclean, Rhona, Rangarajan, Savita, Williams, Michael and Collins, Peter W (2011) Incidence of factor VIII inhibitors throughout life in severe hemophilia A in the United Kingdom. Blood, 117 (23), 6367-6370. (doi:10.1182/blood-2010-09-308668).

Abstract

The age-adjusted incidence of new factor VIII inhibitors was analyzed in all United Kingdom patients with severe hemophilia A between 1990 and 2009. Three hundred fifteen new inhibitors were reported to the National Hemophilia Database in 2528 patients with severe hemophilia who were followed up for a median (interquartile range) of 12 (4-19) years. One hundred sixty (51%) of these arose in patients ≥ 5 years of age after a median (interquartile range) of 6 (4-11) years' follow-up. The incidence of new inhibitors was 64.29 per 1000 treatment-years in patients < 5 years of age and 5.31 per 1000 treatment-years at age 10-49 years, rising significantly (P = .01) to 10.49 per 1000 treatment-years in patients more than 60 years of age. Factor VIII inhibitors arise in patients with hemophilia A throughout life with a bimodal risk, being greatest in early childhood and in old age. HIV was associated with significantly fewer new inhibitors. The inhibitor incidence rate ratio in HIV-seropositive patients was 0.32 times that observed in HIV-seronegative patients (P < .001). Further study is required to explore the natural history of later-onset factor VIII inhibitors and to investigate other potential risk factors for inhibitor development in previously treated patients.

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Contributors

Author: Savita Rangarajan

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