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Inhibitor development in previously untreated patients with severe haemophilia A: a nationwide multicentre study in
K Vepsäläinen1, R Lassila2, M Arola3
1Department of Paediatrics, Kuopio University Hospital, Kuopio, Finland. kaisa.vepsalainen@kuh.fi.
Insights
Inhibitor development (ID) in severe haemophilia A is a serious complication. Early intensive primary prophylaxis, particularly via ports, helps prevent bleeds and reduce ID incidence in previously untreated patients.
Area of Science:
- Hematology
- Immunology
- Pediatrics
Background:
- Inhibitor development (ID) is a significant treatment complication for individuals with haemophilia.
- Neutralizing antibodies, known as inhibitors, pose a serious challenge in haemophilia management.
Purpose of the Study:
- To evaluate the incidence and risk factors of inhibitor development (ID) in previously untreated patients (PUPs) with severe haemophilia A.
- This nationwide study aimed to identify factors influencing ID in a vulnerable patient group.
Main Methods:
- A nationwide multicentre study in Finland enrolled 62 previously untreated patients (PUPs) with severe haemophilia A.
- Patients were monitored for inhibitor development (ID) with at least 75 exposure days (EDs).
- Data on prophylaxis type, FVIII product, genotype, and bleeding history were collected.
Main Results:
- The cumulative incidence of inhibitor development (ID) was 21% (13/62), with 16% (10/62) developing high-titre inhibitors.
- Early intensive primary prophylaxis was administered to 82% of patients, often via central venous access devices.
- A history of major bleeding was associated with an increased risk of ID (aHR, 4.0).
Conclusions:
- Despite a high prevalence of high-risk genotypes, the overall incidence of inhibitor development (ID) was low.
- Early intensive primary prophylaxis, combined with strategies to prevent bleeds, appears effective in reducing ID risk.
- Patient-related factors, such as a history of major bleeds, remain important considerations in ID risk assessment.
Introduction:
Currently the most serious treatment complication of haemophilia is the inhibitor development (ID), i.e. neutralizing antibody development.
Aim:
This nationwide multicentre study in Finland evaluated the incidence and risk factors of ID in previously untreated patients (PUPs) with severe haemophilia A (FVIII:C < 0.01 IU mL(-1) ).
Methods:
We enrolled all PUPs (N = 62) born between June 1994 and May 2013 with at least 75 exposure days (EDs) to screen ID during follow-up extending to September 2013.
Results:
Thirteen ID (21% of 62) occurred; 10 (16% of 62) with high titre. Fifty-one patients (82%) were on primary prophylaxis (regular prophylaxis before the age of 2 and before the first joint bleed) from the median age of 11.4 months, 90% via a central venous access device. The initial product was rFVIII in 63% and pd-FVIII in 37%, moreover in 24% pd-FVIII was switched to rFVIII concentrate during the 75 EDs. Non-transient inhibitors developed in 9/51 (17.6%; 13.7% high titre) children with primary and in 4/11 (36.4%; 27.3% high titre) patients with secondary prophylaxis (P = 0.24). Overall, 74% had a high-risk genotype similarly distributed among the prophylaxis groups. The history of a major bleed enhanced ID (aHR, 4.0; 95% CI, 1.2-13.7), whereas FVIII treatment intensity or source and early implantation of ports did not increase ID risk.
Conclusion:
The cumulative incidence of ID was low notwithstanding prevalent high-risk mutations. Despite patient-related risk factors, our management involving early intensive primary prophylaxis via ports helps to prevent bleeds and lower the incidence of inhibitors.
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