[Study on risk factors and follow-up of 26 hemophilia A children with inhibitors].

OBJECTIVE: To study the risk factors, characteristics and treatment of factor Ⅷ (F Ⅷ) inhibitor in Chinese children with hemophilia A (HA) through a retrospective case-control survey; To investigate the bleeding phenotype before and after inhibitor formation.

METHODS: The clinical data of outpatients and inpatients with HA children from January 2010 to December 2014 were collected. A case control study was performed to investigate the risk factors for inhibitor formation.

RESULTS: A total of 445 HA children were enrolled with 82(18.4%) severe, 269(60.5%) moderate, and 94(21.1%) mild cases; 26(5.8% ) patients, among whom 13 were severe HA and 13 moderate HA, had inhibitor (9 low titer inhibitors, and 17 high titer inhibitors). No inhibitor was found in mild HA patients. Intensive treatment (P= 0.030, HR=4.435, 95% CI 1.150-17.094) was a risk factor for inhibitor generation. After inhibitor formation, 2 patients received small dose rituximab for inhibitor eradication, and one of them also received ITI therapy. When bleeding, 65.2% (15/23) inhibitors received PCC treatment to stop the bleeding, 8.7% (2/23) inhibitors didn't receive any medication, and 26.1% (6/23) inhibitors chose intermittent small dose FⅧ treatment; Among those patients who didn't received inhibitor eradication, 87.5%(7/8) patients with low titer inhibitor showed gradual disappearance, and the median time was 3 months; 84.6% (11/13) patients with high-titer inhibitors remained positive in 12-48 months showing a gradual decrease with time; 7.7% (1/13) high titer inhibitors showed gradual disappearance in 2 years. The annual traumatic and provoked bleeding frequency for joints, skin and soft tissue showed no difference after inhibitor formation.

CONCLUSION: Intensive F Ⅷ treatment was a risk factor for inhibitor formation. The inhibitor didn' t increase bleeding frequency in HA children.