Preventing bleeds by treatment: new era for haemophilia changing the paradigm.

INTRODUCTION: Coagulation products have allowed patients with severe haemophilia to lead a normal life. This is, however, only true for patients who received an early diagnosis and could start with primary prophylaxis. The absence of a positive family history for haemophilia, in the majority of children with severe haemophilia, postpones the age that treatment can be started. This makes general awareness of the clinical presentation important and a proper diagnosis a prerequisite for progress. The long delay between joint bleeding and overt arthropathy has been an important factor in the delay of implementation of primary prophylaxis. After the development of guidelines on 'how to treat', implementation of the advised practice is needed. Data collection of current treatment regimens in haemophilia centres will support the further optimization of the care for persons with haemophilia and further optimize treatment guidelines. Episodic ('on demand') therapy as a treatment strategy for severe haemophilia needs reconsideration. CONCLUSION: In an era where clotting factor concentrates are abundant and gene therapy a reality, all patients with severe haemophilia should be offered a strategy of bleeding prevention.

Validity of assessing inhibitor development in haemophilia PUPs using registry data: the EUHASS project.

Inhibitory antibodies to exogenous FVIII/FIX are a major complication of haemophilia treatment. Up to 30% of previously untreated patients (PUPs) with severe haemophilia A develop inhibitors, most likely during the initial 50 exposure days to concentrate. In addition to classical cohort studies, a European monitoring system (EUHASS) has been set up to evaluate inhibitor development in PUPs. The present study addresses the reliability of estimating the cumulative incidence of inhibitor development in this registry. Data from the retrospective CANAL cohort study, including 288 PUPs with severe haemophilia A and complete treatment records until the 50th exposure to FVIII, were used to simulate the consequences of several cross-sectional sampling techniques on the estimated incidence of inhibitors. Both mathematical calculus and computer modelling were applied to study the effects of sample size and the introduction of a new product. For existing concentrates, both longitudinal cohort study methods and the EUHASS method yielded similar estimates of the cumulative incidence of inhibitor cases over a 5-year time period: 27.9% (95% CI: 21-36) vs. 29.4% (22-38). For a newly introduced concentrate, a reliable estimate of inhibitor incidence with the EUHASS method could only be made after 3-4 years, even in large datasets. The results from EUHASS in inhibitor incidence in PUPs are expected to be valid. After introduction of a new concentrate, the inhibitor incidence on this concentrate can only be reliably determined after an observation period of several years.

Treatment-related risk factors of inhibitor development in previously untreated patients with hemophilia A: the CANAL cohort study.

The CANAL Study (Concerted Action on Neutralizing Antibodies in severe hemophilia A) was designed to describe the relationship between treatment characteristics and inhibitor development in previously untreated patients with severe hemophilia A. This multicenter retrospective cohort study investigated 366 consecutive patients born between 1990 and 2000. The outcome was clinically relevant inhibitor development, defined as the occurrence of at least 2 positive inhibitor titers combined with a decreased recovery. Eighty-seven (24%) patients developed inhibitors (69 high titer [19%]). The incidence of inhibitors appeared to be associated with age at first treatment, decreasing from 41% for those treated within the first month of age to 18% in those treated after 18 months; after adjustment for treatment intensity, this association largely disappeared. Surgical procedures and peak treatment moments at start of treatment increased inhibitor risk (relative risk [RR], 3.7; 95% confidence interval [CI], 2.0-7.1; and RR, 3.3; CI, 2.1-5.3, respectively). Regular prophylaxis was associated with a 60% lower risk than on-demand treatment (RR, 0.4; CI, 0.2-0.8). Our findings suggest that the previously reported associated between an early age at first exposure and the risk of inhibitor development is largely explained by early, intensive treatment. The latter appears to be an independent risk factor for inhibitor development. In addition, early, regular prophylaxis may protect patients with hemophilia against the development of inhibitors.