Immune tolerance treatment in haemophilia patients with inhibitors: the Spanish Registry

We present a retrospective study of immune tolerance treatment (ITT) carried out in 42 Spanish haemophiliac patients. Most of the patients were high responders (39/42), with a median maximum titre of 67 Bethesda units (BU) (range 6-2984). The median inhibitor titre at the start the ITT was 11 BU (range 1-256 BU) and the median age of the patients was 7 years (range 0-57). The mean factor dosage was 140 IU kg bodyweight(-1) day(-1) (range 25-500). In most of the ITTs, plasma-derived factor concentrate of intermediate and high purity was used. The inhibitor was eradicated in 26/38 (68%) of the patients who completed the treatment and two patients changed their status from high to low responders. Multivariate logistic regression analysis showed that three significant variables were associated with the highest probability of success: (i) the use of low factor doses for ITT (< or = 100 IU kg(-1) day(-1); P = 0.0106; 95% CI 0.000289-0.342); (ii) a titre of < 10 BU at start of ITT (P = 0.0286; 95% CI 0.00253-0.7189) and (iii) a lower maximum titre (P = 0.0214; 95% CI 0.98-0.9994).