Product type and the risk of inhibitor development in nonsevere haemophilia A patients: a case‒control study

Inhibitor development is a major complication of treatment with factor VIII concentrates in nonsevere haemophilia A. It has been suggested that plasma-derived factor VIII (FVIII) concentrates elicit fewer inhibitors than recombinant FVIII concentrates, but studies in severe haemophilia A patients have shown conflicting results. We designed a case‒control study to investigate the clinical and genetic risk factors for inhibitor development in nonsevere haemophilia A patients. We investigated whether the type of FVIII concentrate was associated with inhibitor development in nonsevere haemophilia A patients. This nested case‒control study includes 75 inhibitor patients and 223 controls, from a source population of the INSIGHT study, including all nonsevere haemophilia A patients (FVIII:C 2–40%) that were treated with FVIII concentrates in 33 European and one Australian centre. Cases and controls were matched for date of birth and cumulative number of exposure days (CED) to FVIII concentrate. A conditional logistic regression model was used to calculate unadjusted and adjusted odds ratios. No increased risk for inhibitor development was found for any type of FVIII concentrate; either when comparing recombinant FVIII concentrates to plasma-derived FVIII concentrates (adjusted odds ratio 0·96, 95% confidence interval (CI) 0·36–2·52) or for specific types of FVIII concentrates

Desmopressin in moderate hemophilia a patients: A treatment worth considering

Desmopressin increases endogenous factor VIII levels in hemophilia A. Large inter-individual variation in the response to desmopressin is observed. Patients with a lower baseline factor VIII activity tend to show a reduced response, therefore, desmopressin is less frequently used in moderate hemophilia A patients (baseline factor VIII activity 1-5 international units/deciliter), even though factor VIII levels may rise substantially in some of them. We aim to describe the response to desmopressin in moderate hemophilia A patients and to identify predictors. We selected data on 169 patients with moderate hemophilia from the multicenter Response to DDAVP In non-severe hemophilia A patients: in Search for dEterminants (RISE) cohort study. Adequate response to desmopressin was defined as a peak factor VIII level ≥ 30, and excellent response as ≥ 50 international units/deciliter after desmopressin administration. We used univariate and multiple linear regression techniques to analyze predictors of the peak factor VIII level. Response was considered adequate in 68 patients (40%), of whom 25 showed excellent response (15%). Intravenous administration, age, pre-desmopressin factor VIII activity and von Willebrand factor antigen, peak von Willebrand factor activity and desmopressin-induced rise in von Willebrand factor antigen were significant predictors of peak factor VIII level and explained 65% of the inter-individual variation. In 40% of moderate hemophilia A patients, desmopressin response was adequate, thus it is important not to withhold this group of patients from desmopressin responsiveness. Among the six predictors that we identified for desmopressin-induced factor VIII rise, factor VIII activity and desmopressin-induced rise in von Willebrand factor antigen had the strongest effect

Treatment-related risk factors for inhibitor development in non-severe hemophilia A after 50 cumulative exposure days: a case-control study

Background Non-severe hemophilia A patients have a life-long inhibitor risk. Yet, no studies have analyzed risk factors for inhibitor development after 50 factor VIII (FVIII) exposure days (EDs). Objectives This case-control study investigated treatment-related risk factors for inhibitor development in non-severe hemophilia A and assessed whether these risk factors were different for early versus late inhibitor development. Patients/Methods Non-severe hemophilia A patients (FVIII:C 2%-40%) were selected from the INSIGHT study. Inhibitor-positive patients were defined as early (50EDs) cases and matched to 1-4 inhibitor-negative controls by year of birth, cumulative number of EDs, and center/country. We investigated treatment intensity during the last 10 EDs prior to inhibitor development. Intensive treatment was defined as: surgery, peak treatment (10 consecutive EDs), and high mean FVIII dose (>45 IU/kg/ED). Odds ratios (OR) were calculated by logistic regression. Results Of 2709 patients, we analyzed 63 early and 26 late cases and 195 and 71 respectively matched controls. Peak treatment was associated with early and late inhibitor risk (crude OR 1.8, 95% confidence interval [CI] 1.0-3.4; 4.0, 95%CI 1.1-14.3). This association was slightly less pronounced after adjustment for mean FVIII dose. High mean FVIII dose was also associated with early and late inhibitor risk (crude OR 2.8, 95%CI 1.5-5.1; 4.5, 95%CI 1.2-16.6). Surgery increased inhibitor risk for early cases. This was less pronounced for late cases. Conclusions Our findings suggest that intensive FVIII treatment remains a risk factor for inhibitor development in non-severe hemophilia A after more than 50 EDs. Therefore, persistent caution is required throughout the life-time treatment course.Clinical epidemiolog

INSIGHT in risk factors and treatment of inhibitors in nonsevere hemophilia A

Hemophilia A is an inherited X-linked bleeding disorder that occurs in male offspring of carrier females. In these individuals a mutation in the F8 gene, located on the X-chromosome, causes a deficiency of the factor VIII protein, clotting factor VIII. The worldwide prevalence of hemophilia is 1 in 5000 live male births, with one-third of the patients affected by severe hemophilia A and two-thirds of the patients have nonsevere disease. In patients with hemophilia A there is an impaired hemostasis due to a reduction of their factor VIII plasma level. This is associated with clinical symptoms of spontaneous bleeds in joints and muscles. An extremely severe and challenging complication of treatment with factor VIII concentrates in hemophilia A patients is the development of anti-factor VIII antibodies that inhibit (neutralize) the factor VIII activity, also referred to as inhibitors. This complication occurs in 25-30% of the severe hemophilia patients. Inhibitors seem to occur less frequently in nonsevere hemophilia A patients, although studies on inhibitor incidence in this group of patients are scarce. When a nonsevere hemophilia A patient develops an inhibitor, the phenotype of the disease may change dramatically. Nonsevere haemophilia A patients would normally only experience incidental bleeding episodes, but after inhibitor development the bleeding phenotype may aggravate dramatically, especially if the inhibitor reduces the endogenous factor VIII plasma levels. This is associated with an increased morbidity and mortality. This thesis focuses on the risk factors and treatment of inhibitors in nonsevere hemophilia A

Dissecting intensive treatment as risk factor for inhibitor development in haemophilia

Clinical epidemiolog

Treatment-related risk factors for inhibitor development in non-severe hemophilia A after 50 cumulative exposure days: A case-control study

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RISE- response to DDAVP in moderate/mild haemophilia A patients: in search for determinants

Clinical epidemiolog

Clinical risk factors in the development of inhibitors in non-severe hemophilia A patients: the first results of the INSIGHT case-control study

Clinical epidemiolog