Inhibitor incidence in an unselected cohort of previously untreated patients with severe hemophilia B: a PedNet study

The incidence of factor IX (FIX) inhibitors in severe hemophilia B (SHB) is not well defined. Frequencies of 3-5% have been reported but most studies to date have been small, including patients with different severities, and without prospective follow up for inhibitor incidence. The study objective was to investigate the inhibitor incidence in patients with SHB followed up for to 500 exposure days (ED), the frequency of allergic reactions, and the relationship with genotypes. Consecutive previously untreated patients (PUP) with SHB enrolled into the PedNet cohort were included. Detailed data was collected for the first 50 ED, followed by the annual collection of the inhibitor status and allergic re-actions. The presence of inhibitors was defined by at least two consecutive positive samples. Additionally, data on FIX gene mutation was collected. One hundred and fifty-four PUP with SHB were included; 75% were followed up until 75 ED, and 43% until 500 ED. Inhibitors developed in 14 patients (seven high-titer). The median number of ED at inhibitor manifestation was 11 (interquartile range [IQR]: 6.5-36.5). The cumulative inhibitor incidence was 9.3% (95% Confidence Interval [CI]: 4.4-14.1) at 75 ED, and 10.2% (95% CI: 5.1-15.3) at 500 ED. Allergic reactions occurred in four (28.6%) inhibitor patients. Missense mutations were most frequent (46.8%) overall but not associated with inhibitors. Nonsense mutations and deletions with large structural changes comprised all mutations among inhibitor patients and were associated with an inhibitor risk of 26.9% and 33.3%, respectively. In an unselected, well-defined cohort of PUP with SHB, the cumulative inhibitor incidence was 10.2% at 500 ED. Nonsense mutations and large deletions were strongly associated with the risk of inhibitor development. The ‘PedNet Registry’ is registered at clinicaltrials.gov; identifier: {"type":"clinical-trial","attrs":{"text":"NCT02979119","term_id":"NCT02979119"}}NCT02979119.     

Impact of high‐risk thrombophilia status on recurrence among children with a first non‐central‐venous‐catheter‐associated VTE: an observational multicentre cohort study

Deficiency of antithrombin (AT), protein C (PC) or protein S (PS) constitutes a major risk factor for venous thromboembolism (VTE). Individuals at high risk for recurrence who benefit from screening need to be identified. The primary study objective was to determine the individual recurrence risk among children with a first non‐central‐venous‐catheter‐associated VTE with respect to their thrombophilia status and to evaluate if the clinical presentation at first VTE onset differs between children with AT, PC or PS deficiency versus no thrombophilia. We calculated the absolute risk of VTE recurrence and event‐free‐survival adjusted for thrombophilia, age, sex and positive family VTE history in 161 consecutively enrolled paediatric VTE patients. The presence of a deficiency relative to no thrombophilia was evaluated as a potential predictor of recurrence. Predictors for recurrence were AT deficiency (hazard ratio/95% CI: 6·5/2·46–17·2) and female gender (2·6/1·1–6·35). The annual recurrence rates (95% CIs) were 5·4% (2·6–10) in AT‐deficient children, 1·3% (0·3–3·8) in patients with PC deficiency, 0·7% (0·08–2·4) in the PS‐deficient cohort and 0·9% (0·4–1·8) in patients with no thrombophilia. Positive family VTE history or combined thrombophilias did not predict recurrence. Given the overall annual incidence rate of recurrence of 1·5% we suggest screening for AT deficiency in children with VTE.     

Cone and platelet analyser (CPA): a new test for the prediction of bleeding among thrombocytopenic patients

The risk of bleeding among thrombocytopenic patients was evaluated using our new cone and platelet analyser (CPA) test. Using this test, adherence of platelets was quantitated on extracellular matrix and expressed as percent of surface coverage (SC) and the average size (AS) of aggregates. 42 thrombocytopenic patients with ITP (n=23), post chemotherapy (n=12) and others (n=7) were tested over a total of 82 visits. On each visit, complete blood count and CPA tests were performed and patients were evaluated for evidence of bleeding (found in 40 visits). Bleeding patients had significantly lower platelet counts (27.4 ± 22.0 v 47.1 ± 21.0 × 10⁹/l), lower haematocrit values (30.2 ± 8.1 v 35.2 ± 6.6%), lower MPV (6.83 ± 1.89 v 8.98 ± 1.13 fl), and lower SC (4.87 ± 3.95 v 10.33 ± 5.48%) and AS (33.99 ± 14.94 v 52.9 ± 24.34 μm²). Univariate analysis yielded platelet count 20.0 × 10⁹/l, MPV 8fl, haematocrit <35%, SC < 5%, AS 40 μm² as significantly associated with bleeding, whereas only MPV and SC were associated with bleeding (OR 6.95, CI 2.25–21.46 and OR 4.27, CI 1.29–14.16, respectively) by multivariate analysis. When taken together, 21/22 of patients (95%) with both low SC (<5%) and low MPV (<8.0 fl) had bleeding symptoms, whereas only 9/43 (21%) patients with both these parameters above these values experienced bleeding symptoms. We conclude that the CPA test and the parameter SC (<5%) together with MPV (8 fl) might be used as independent predictors of bleeding in the management of thrombocytopenic patients.     

Evaluation of a new immunochromatographic test for Helicobacter pylori IgG antibodies in elderly symptomatic patients

Aim: To determine the diagnostic value of a new serum and whole blood serological IgG antibody test, FlexPack HP, for the diagnosis of Helicobacter pylori in elderly symptomatic patients. Methods: 94 consecutive symptomatic patients who underwent upper endoscopy were studied (mean age, 62.6 years). On endoscopy, the presence of H. pylori infection was examined by biopsies from gastric antrum and body for rapid urease test and histologic examination. Blood was drawn prior to endoscopy and both blood and serum were immediately analyzed for human IgG antibodies to H. pylori by a new commercially available qualitative immunochromatographic method, FlexPack HP. This test incorporates high-molecular weight cell-associated proteins (HM-CAP), which are highly specific for H. pylori IgG antibodies. Results: Overall agreement for FlexPack HP whole blood vs FlexPack HP serum was 100%, and agreement with biopsy results was 71%. The gold standard (detection of H. pylori by histology or urease test) identified H. pylori in 61 patients (65%). Complete agreement was observed between the gold standard test and the serology kit in 72% (68/94) of sera (51 positive and 17 negative). Disagreement was found in sera of 26 patients; 16 sera were negative by the gold standard and positive by FlexPack HP and 10 patients were found negative by serology. The sensitivity of FlexPack HP was 84% and the specificity 52% when compared with the gold standard. Conclusions: FlexPack HP serum and whole blood test is a simple and reliable method for the detection of H. pylori antibodies, with 100% agreement between the serum and blood results. In the elderly symptomatic patients the sensitivity of FlexPack HP was similar to that of other serologic tests, but the specificity was relatively low, limiting its use in this population. (Received Jan. 7, 1998; accepted Aug. 28, 1998)     

Treatment of traumatic bleeding with recombinant factor VIIa

Surgical intervention failed to stop life-threatening bleeding caused by injury complicated by severe coagulopathy. Administration of recombinant factor VIIa immediately corrected the coagulopathy and bleeding stopped.     

A highly sensitive thrombin generation assay for assessment of recombinant activated factor VII therapy in haemophilia patients with an inhibitor

Bypass agents are the common treatment for haemophilia patients who develop inhibitory antibodies. Laboratory assessment of the efficacy of bypassing agent therapy is a challenge. In the present work we modified the conditions triggering thrombin generation (TG) assay in order to find the most sensitive assay for detection of rFVIIa and its analogue NN1731 in haemophilic plasma. TG was measured in samples of normal plasma, plasma of haemophilia patient with inhibitors, as well as haemophilia induced plasma. Recalcification-induced TG was compared to tissue factor (TF) -induced TG in the presence and absence of rFVIIa and NN1731. Recalcification-induced TG (without TF) in haemophilic plasma yielded baseline flat curves, with increased TG as a consequence of spiking the plasma rFVIIa. Using our system, we observed both dose-dependence and time-dependence of rFVIIa effect on TG. Elevated concentrations of TF mask the difference between rFVIIa-treated and non-treated haemophilic plasma. NN1731 yielded normalisation of recalcification-induced TG curves (without TF) which may reflect high potency. In conclusion, we suggest that triggering TG by recalcification-only may be the most sensitive assay for determining the impact of bypassing agents in haemophilic plasma, and may serve as a caution surrogate safety marker in future studies.