The PFA‐100®: a potential rapid screening tool for the assessment of platelet dysfunction

The PFA‐100^® is a device that simulates high shear dependent platelet function in vitro and thus is particularly useful for screening for von Willebrand's disease (VWD). The aim of this study was to assess the overall potential of the PFA‐100^® as a primary clinical screening tool using the wide spectrum of clinical samples assessed for platelet function within our institution. The PFA‐100^® test was performed using both collagen/ADP (CADP) and collagen/epinephrine (CEPI) cartridges on samples from 337 patients with a wide variety of haemostatic defects. One hundred and eighty‐two patients were defined as having normal platelet function based on classical laboratory tests and von Willebrand factor levels. The overall clinical sensitivity of the PFA‐100^® for platelet abnormalities (including VWD) was 81% for CADP and 86% for CEPI. The overall specificity was found to be 82% for CADP and 80% for CEPI. When utilizing both cartridges in combination (with both results either higher or lower than the upper cutoff of the normal ranges), the overall false positive and false negative rates were 12% and 6%, respectively. The PFA‐100^® proved to be sensitive in detecting classical defects by giving prolonged closure times in samples from patients with major platelet function defects (e.g. von Willebrand's disease, Glanzmann's thrombasthenia and Bernard Soulier syndrome). However, there were a small number of false negative results (6%) obtained with various milder platelet defects (e.g. Hermansky Pudlak syndrome, storage pool and release defects, type I VWD and macrothrombocytopenia). The PFA‐100^® test provides a useful rapid screening tool and should increase the efficiency and reduce the cost of the routine diagnosis of platelet dysfunction.     

Enhanced ex vivo inhibition of platelet function following addition of dipyridamole to aspirin after transient ischaemic attack or ischaemic stroke: first results from the TRinity AntiPlatelet responsiveness (TrAP) study

Ex vivo dipyridamole ‘non‐responsiveness’ has not been extensively studied in ischaemic cerebrovascular disease. Platelet surface marker expression, leucocyte‐platelet complex formation and inhibition of platelet function at high shear stress as detected by the PFA‐100^® Collagen‐Adenosine‐diphosphate (C‐ADP) and Collagen‐Epinephrine cartridges was assessed in 52 patients within 4 weeks of transient ischaemic attack (TIA) or ischaemic stroke on aspirin, and then 14 d (14 d) and >90 d (90 d) after adding dipyridamole. A novel definition of ‘Dipyridamole non‐responsiveness’ was used. The median C‐ADP closure time increased following addition of dipyridamole, remained elevated at 90 d (P ≤ 0·03), and was unaffected by aspirin dose. 59% at 14 d and 56% at 90 d were ‘dipyridamole non‐responders’ on the PFA‐100. The proportion of non‐responders at 14 and 90 d was similar (P = 0·9). Compared with baseline (4·6%), median monocyte‐platelet complexes increased at 14 d (5·0%, P = 0·03) and 90 d (4·9%, P = 0·04). Low C‐ADP closure times were associated with increased monocyte‐platelet complexes at 14 d (r = ?0·32, P = 0·02) and 90 d (r = ?0·33, P = 0·02). Monocyte‐platelet complexes increased in the subgroup of dipyridamole non‐responders on the PFA‐100 (P ≤ 0·045), but not in responders (P ≥ 0·5), at 14 and 90 d versus baseline. Additional inhibition of platelet function has been detected with the PFA‐100 when dipyridamole is added to aspirin. Elevated monocyte‐platelet complexes may contribute to ex vivo dipyridamole non‐responsiveness.     

Prospective observational cohort study of the association between thromboelastometry,coagulation and platelet parameters and bleeding in patients with haematological malignancies‐ The ATHENA study

Previous studies have shown that total platelet count (TPC) inadequately predicts bleeding in thrombocytopenic patients with haematological malignancies. This prospective cohort study evaluated whether rotational thromboelastometry (ROTEM), coagulation or other platelet parameters were more strongly associated with bleeding than TPC. Adults treated at two UK haematology centres for haematological malignancy were enrolled if they had thrombocytopenia (TPC ≤ 50 × 10⁹/l) at beginning of, or during treatment (International Standard Randomized Controlled Trial Number 81226121). TPC and bleeding symptoms were recorded daily for up to 30 d or until platelet count recovery, hospital discharge or death. Blood samples were tested thrice weekly using ROTEM, Platelet Function Analyser (PFA)‐100^®, coagulation and platelet cytometry assays. Bleeding symptoms and TPC from 49/50 enrolled participants who completed the study were recorded on 754/760 study days. Mean platelet volume and PFA‐100^® closure times were frequently inestimatable because of thrombocytopenia. TPC, absolute immature platelet number (AIPN) and ROTEM maximum clot firmness were significantly associated with bleeding on the day after blood sampling. Only AIPN was associated with bleeding after adjustment of test results for TPC (Odds Ratio 0·52, 95% confidence interval 0·28–0·97; P = 0·038). In a predictive model, AIPN was superior to TPC for predicting bleeding. This study indicates that AIPN may be more clinically useful than TPC at predicting bleeding.     

The PFA‐100™ system for the assessment of platelet function in normotensive and hypertensive pregnancies

Platelet function was studied in 30 pregnant women: 14 normotensive (C), and 16 affected by pregnancy‐induced hypertension (PIH). Platelet aggregometry (PA) on platelet‐rich plasma according to Born was compared with the new PFA‐100^? System (Dade International Inc, Miami, USA). This device evaluates platelet function (expressed in seconds as closure time, CT) in anticoagulated whole blood ex vivo at high shear rates. PA (expressed as percentage of light transmission) and CT were measured at baseline and after incubation with L‐Arginine (L‐Arg). MANOVA for repeated measures showed that L‐Arg incubation significantly decreased PA (F=7.2, P < 0.05) and increased CT (F=6.05, P < 0.05) in the whole population of pregnant women. Moreover, we analysed separately both parameters in C and in PIH subjects. No differences in PA were found in both groups, neither at baseline nor after L‐Arginine incubation. In contrast, CT was significantly longer in PIH in comparison to C before (95.9 s vs. 84 s, P < 0.05) as well after (115 s vs. 92 s, P < 0.05) L‐Arginine incubation. Data from PFA‐100^? confirm our previous reports that during pregnancy the L‐Arginine: Nitric Oxide pathway regulates platelet function. In hypertensive patients a significant decrease in platelet function was found by using the PFA‐100^? system.     

Clinical phenotype in heterozygote and biallelic Bernard‐Soulier syndrome—A case control study

Bernard‐Soulier syndrome (BSS) is a rare severe autosomal recessive bleeding disorder. To date heterozygous carriers of BSS mutations have not been shown to have bleeding symptoms. We assessed bleeding using a semi‐quantitative questionnaire, platelet parameters, PFA‐100 closure times, ristocetin response, GP Ib/IX expression and VWF antigen in 14 BSS patients, 30 heterozygote carriers for related mutations and 29 controls. Eight mutations in GP1BA, GP1BB or GP9 were identified including four previously unknown pathogenic mutations. Subjects with BSS reported markedly more mucocutaneous bleeding than controls. Increased bleeding was also observed in heterozygotes. Compared to controls, patients with BSS had lower optical platelet counts (P < 0.001), CD61‐platelet counts (P < 0.001) and higher mean platelet volume (17.7 vs. 7.8 fL, P < 0.001) and ristocetin response and closure times were unmeasurable. Heterozygotes had higher MPV (9.7 fL, P < 0.001) and lower platelet counts (P < 0.001) than controls but response to ristocetin and closure times were normal. The VWF was elevated in both BSS and in heterozygotes (P = 0.005). We conclude that heterozygotes for BSS mutations have lower platelet counts than controls and show a bleeding phenotype albeit much milder than in BSS. Both patients with BSS and heterozygote carriers of pathogenic mutations have raised VWF. Am. J. Hematol. 90:149–155, 2015. © 2014 Wiley Periodicals, Inc.     

Platelet function analyser (PFA‐100) results and von Willebrand factor deficiency: a 16‐year ‘real‐world’ experience

The platelet function analyser (PFA‐100) is a biological tool designed to explore primary haemostasis. This system has thus been widely demonstrated as reliable in detecting von Willebrand factor (VWF) deficiency. However, most studies were based on patients benefitting from regular medical care and accurate diagnosis, and it would seem probable that the results were somewhat optimistic, and do not reflect its performances in ‘real‐world’ situations. We have chosen to study the reliability of PFA‐100 for screening VWF ristocetin cofactor (VWF:RCo) deficiency. We retrospectively analysed the results (n = 6431) of 4027 patients referred to our centre between October 1997 and June 2013 and in whom PFA‐Epi, PFA‐ADP, and VWF:RCo activity had been evaluated. We studied the influence of blood group on the results and the performances of each method in a subgroup of 213 patients with genetically confirmed von Willebrand disease. We have shown that the PFA‐100 system, in our experience, constitutes an excellent screening test for detecting VWF:RCo deficiency, whatever the clinical situation, in ‘real‐world’ conditions. The negative predictive value (NPV), the positive predictive value, the sensitivity and the specificity were respectively: 0.98, 0.51, 0.98 and 0.40. When values adjusted for blood group are used, NPV and sensitivity are inferior to those using normal values which have not been adjusted for blood group. We have shown the PFA‐100 method to be more efficient in screening for VWF deficiency than the VWF:RCo technique.     

Evaluation of a universal point‐of‐issue assay for bacterial detection in buffy coat platelet components

Bacterial contamination of platelet concentrates poses a major post‐transfusion infectious risk. This study was aimed at evaluating the efficacy of the BacTx ^® assay (Immunetics Inc.) for bacterial detection in leucocyte‐reduced buffy coat platelet pools and for its sensitivity in detecting clinical isolates, including bacteria that form surface‐attached aggregates (biofilm positives). Platelet pools were inoculated at bacterial concentrations of 0·8–13 CFU/ml. The BacTx ^® assay detected all species at concentrations ≥10³ CFU/ml within 20–69 h of platelet incubation. Detection of slow‐growing and biofilm‐forming strains was delayed in comparison with the other strains. This assay could be used as a point‐of‐issue method to increase the safety of the platelet supply.     

Artefactually‐normal automated platelet counts due to malaria‐infected RBC

Protein aggregates, red cell or white cell fragments are known to interfere with platelet counts in automated blood analysers, both by aperture impedance and optical technologies. When a falsely high value is suspected, interference by pseudo‐platelet particles can be confirmed by systematic examination of stained blood films. The method that best avoids these sources of interference is the reference, immunological platelet count. We describe a case of treated malaria with a false normal platelet count. The blood smear revealed small red cells, infected by trophozoites of Plasmodium falciparum, that interfered with the platelet count. The Cell Dyn^® 4000 shows different patterns of interference by infected red cells in its impedance and optical counts, and thrombocytopenia was suspected immediately. This was confirmed by a phase‐contrast microscopic platelet count.     

Therapeutic efficacy of platelet components treated with amotosalen and ultraviolet A pathogen inactivation method: results of a meta‐analysis of randomized controlled trials

Background and Objectives There are conflicting data regarding the therapeutic efficacy of platelets inactivated using amotosalen and ultraviolet A light. We have performed a meta‐analysis to summarize the results of different randomized controlled trials (RCT). Materials and Methods Five RCTs reported through March 2011 met the criteria for meta‐analysis. Weighted mean difference (WMD) in corrected count increment (CCI) at 1 h, CCI‐24 h, and transfusion interval (days) and summary odds ratio (OR) of bleeding in inactivated platelet (I‐P) group vs. noninactivated platelet (C‐P) group were calculated across studies. Results Randomized controlled trials were statistically homogeneous when we analysed CCI‐24 h, and the transfusion of C‐P was associated with a higher CCI‐24 h when compared with the transfusion of I‐P (WMD, 3 × 10³; 95% CI, 2·32 × 10³–3·69 × 10³; P < 0·00001). RCTs were statistically heterogeneous when we analysed CCI‐1 h, transfusion interval and OR of bleeding. Regarding the OR of bleeding in the I‐P and C‐P groups, it varied by as much as a multiple of four among the trials, from 0·66 to 2·66. When we combined double‐blinded and high methodologic quality score RCTs, the use of I‐P was not statistically associated with an increase in the OR of bleeding when compared with the use of C‐P (OR, 0·97; 95% CI, 0·75–1·27; P = 0·84). Conclusion Although the transfusion of I‐P was associated with lower CCI‐24 h when compared with the transfusion of C‐P, this was not associated with differences in the OR of bleeding between I‐P and C‐P.     

Pharmacology of the Thromboxane Receptor Antagonist and Thromboxane Synthase Inhibitor BM‐531

BM‐531 (N‐tert‐butyl‐N'‐[(2‐cyclohexylamino‐5‐nitrobenzene)sulfonyl]urea), a torasemide derivative, is a novel noncarboxylic thromboxane receptor antagonist and thromboxane synthase inhibitor. Indeed, its affinity for human washed platelet TXA₂ receptors labeled with [3H]SQ‐29548 (IC₅₀= 0.0078 μM) is higher than sulotroban (IC₅₀= 0.93 μM) and SQ‐29548 (IC₅₀= 0.021 μM). Moreover, BM‐531 is characterized by a potent antiaggregatory property. Indeed, on one hand, in human citrated platelet‐rich plasma BM‐531 prevents platelet aggregation induced by arachidonic acid (600 μM) (ED₁₀₀= 0.125 μM), U‐46619, a stable TXA₂ agonist (1 μM) (ED₅₀= 0.482 μM) or collagen (1 μg/mL) (percentage of inhibition: 42.9% at 10 μM) and inhibits the second wave of ADP (2 μM)‐induced aggregation. On the other hand, when BM‐531 is incubated in whole blood from healthy donors, the closure time measured by the recently developed platelet function analyser (PFA‐100®) is significantly prolonged. In addition, at the concentrations of 10 and 1 μM, BM‐531 totally prevents the production of TXB₂ by human platelets activated by arachidonic acid. Finally, at 10 μM, BM‐531 significantly prevents rat fundus contractions induced by U‐46619 but not by prostacyclin. These results suggest that BM‐531, which is devoid of the diuretic property of torasemide, can be regarded as a promising antiplatelet agent.     

Apheresis platelet concentrates contain platelet‐derived and endothelial cell‐derived microparticles

Background and Objectives Microparticles (MP) are membrane vesicles with thrombogenic and immunomodulatory properties. We determined MP subgroups from resting platelets, activated platelets and endothelial cells in donors and apheresis platelet concentrates (PC). Material and Methods MP were double stained with annexin V and CD61 (platelet‐derived MP; PMP), P‐selectin or CD63 (MP from activated platelets) and CD144 plus E‐selectin (endothelial cell‐derived MP; EMP) and detected by flow cytometry in platelet donors (n = 36) and apheresis PC (n = 11; Trima?). Results PC contained MP, mainly from resting platelets [93% (90–95)], and minor fractions of PMP from activated platelets [P‐selectin⁺ or CD63⁺; 4·8% (3·2–7·7) and 2·6% (2·0–4·0)]. Compared to donors, levels of annexin V+ MP, PMP, P‐selectin⁺ and CD63⁺ MP were 1·7‐, 2·3‐, 8·6‐ and 3·1‐fold higher in PC (all P < 0·05). During storage (1–5 days), levels of annexin V+ MP and PMP did not increase, although small increases in the fraction of P‐selectin⁺ or CD63⁺ MP occurred (both P < 0·05). PC also contained EMP, which were 2·6‐ to 3·7‐fold enriched in PC compared to donors (P < 0·05). Conclusions Transfusion of apheresis PC also results in transfusion of HLA‐carrying PMP and EMP. This might counteract the aim of reducing transfused HLA load by leucodepletion. The increases in PMP exposing P‐selectin or CD63 reflect mild platelet activation during storage. We conclude that in leucodepleted platelet apheresis using fluidized particle bed technology, MP are harvested mainly from the donor by apheresis. Improvement in apheresis technology might reduce MP load.     

Usefulness of multiple electrode aggregometry as a screening tool for bleeding disorders in a pediatric hospital

Platelet function testing is a cornerstone in the diagnostic investigation of patients with a bleeding history. Multiple electrode aggregometry (MEA) has been shown to detect von Willebrand disease (VWD), platelet function disorders, and drug-induced bleeding disorders. However, there are few studies supporting its successful use in children. We have implemented and used MEA over 3 years in our hemostasis laboratory in order to study its usefulness to supplement and expedite diagnosis. This is a retrospective, single-center, cohort study of 109 hospitalized children who underwent a laboratory investigation of hemostasis and either had a reported bleeding history or an abnormal bleeding episode. Plasmatic coagulation testing, blood counts, plasmatic von Willebrand testing, platelet function analyzer (PFA-100), and impedance aggregometry (MEA) were performed in all children. Light transmission aggregometry testing was performed as needed. In 41 cases (37.6%), a working diagnosis was made; a primary hemostatic disorder was detected in 35 children (VWD (n = 16), platelet disorder (n = 15), and valproic acid therapy-induced bleeding disorder (n = 3), acetylsalicylic acid-related bleeding (n = 1). In patients diagnosed with VWD, MEA ristocetin-induced platelet aggregation test (RISTO) high test revealed abnormally low aggregation in six patients (43.8%); whereas in patients diagnosed with a platelet function disorder, abnormally low values were found by MEA in only three children (20%). Three of the four children with laboratory evidence of drug-induced platelet dysfunction had abnormalities on MEA. There were no cases in which an abnormal MEA result was used to make a previously undetermined diagnosis. Retrospectively, MEA has demonstrated limited additional diagnostic value beyond standard laboratory testing for detecting defects of primary hemostasis in children.     

Pharmacological Profile and Therapeutic Potential of BM‐573, a Combined Thromboxane Receptor Antagonist and Synthase Inhibitor

BM‐573 (N‐terbutyl‐N′‐[2‐(4′‐methylphenylamino)‐5‐nitro‐benzenesulfonyl]urea), a torsemide derivative, is a novel non‐carboxylic dual TXA₂ synthase inhibitor and receptor antagonist. The pharmacological profile of the drug is characterized by a higher affinity for the thromboxane receptor than that of SQ‐29548, one of the most powerful antagonists described to date, by a complete prevention of human platelet aggregation induced by arachidonic acid at a lower dose than either torsemide or sulotroban, and by a significantly prolonged closure time measured by the platelet function analyser (PFA‐100®). Moreover, at the concentrations of 1 and 10 μM, BM‐573 completely prevented production of TXB₂ by human platelets activated by 0.6 mM of arachidonic acid. BM‐573 prevents rat fundus contraction induced by U‐46619 but not by prostacyclin or other prostaglandins. Despite possessing a chemical structure very similar to that of a diuretic torsemide, BM‐573 has no diuretic activity. BM‐573 does not prolong bleeding time and, unlike some of the other sulfonylureas, has no effect on blood glucose levels. In vivo, BM‐573 appears to have antiplatelet and antithrombotic activities since it reduced thrombus weight and prolonged the time to abdominal aorta occlusion induced by ferric chloride. BM‐573 also relaxed rat aorta and guinea pig trachea precontracted with U‐46619. In pigs, BM‐573 completely antagonized pulmonary hypertensive effects of U‐46619 and reduced the early phase of pulmonary hypertension in models of endotoxic shock and pulmonary embolism. Finally, BM‐573 protected pigs from myocardial infarction induced by coronary thrombosis. These results suggest that BM‐573 should be viewed as a promising therapeutic agent in the treatment of pulmonary hypertension and syndromes associated with platelet activation.     

The spectrum of haemostatic characteristics of women with unexplained menorrhagia

Summary. While an estimated 13% of women with unexplained menorrhagia have von Willebrand disease (VWD), the frequency of other potential bleeding disorders has been uncertain. This study describes the relatively wide range of laboratory characteristics of women with unexplained menorrhagia and presents issues affecting diagnosis in this population. Women with pictorial blood assessment chart (PBAC) score >100 were identified at six U.S. sites and asked to remain drug free for 10 days prior to testing. Blood was collected on one of the first four menstrual cycle days and tested at a central laboratory for procoagulant factors, VWD and fibrinolytic factors. Platelet function testing by PFA‐100^® (PFA) and platelet aggregation with ATP release (PAGG/ATPR) were performed locally using standardized methods. Among 232 subjects, a laboratory abnormality was found in 170 (73.3%), including 124 of 182 White (68.1%) and 34 of 37 Black (91.9%) subjects; 6.0% had VWD, 56.0% had abnormal PAGG/ATPR, 4.7% had a non‐VWD coagulation defect (NVCD) and 6.5% had an abnormal PFA only. AGG/ATPR was reduced in 58.9% of subjects, with multiple agonists in 28.6%, a single agonist in 6.1% and ristocetin alone in 24.2%. Frequencies of PAGG/ATPR defects varied by study site and race; frequencies of VWD and NVCD were similar. Laboratory abnormalities of haemostasis, especially platelet function defects, were common among women with unexplained menorrhagia across multiple U.S. sites. To what degree these abnormalities are clinically significant requires further study.     

Multicentre,randomised phase III study of the efficacy and safety of eltrombopag in Chinese patients with chronic immune thrombocytopenia

Eltrombopag, a thrombopoietin receptor agonist, raises platelet counts and reduces bleeding in patients with immune thrombocytopenia (ITP ). In Chinese patients, eltrombopag was evaluated at an initial dose of 25 mg, vs. 50 mg for non‐Asians, because the plasma exposure of eltrombopag is higher in East Asians. A multicentre, double‐blind, randomised, placebo‐controlled, 8‐week, phase III study enrolled 155 patients with chronic, previously treated ITP . Dosage could be adjusted (25–75 mg/day) to maintain platelet counts 50–250 × 10⁹/l. The primary efficacy endpoint was the proportion of patients with a platelet count ≥50 × 10⁹/l after Day 42. Pharmacokinetics and pharmacodynamics of eltrombopag were analysed in an open‐label extension. After Day 42, 57·7% of eltrombopag‐treated and 6·0% of placebo‐treated patients achieved platelet counts ≥50 × 10⁹/l. Odds of achieving a platelet count ≥50 × 10⁹/l were 26·08 times greater with eltrombopag than placebo (P  <  0·001). Compared with placebo, time to response and duration of response were better with eltrombopag (P  <  0·001) and the odds of any bleeding were reduced by 72% (P  =  0·001). Tolerability, pharmacokinetics, and pharmacokinetics/pharmacodynamics were similar to previous findings in East Asian patients. In conclusion, in Chinese patients with chronic ITP , eltrombopag 25 mg once daily, elevated platelet counts to a safe range and reduced bleeding.     

Can the Platelet Function Analyzer (PFA®)-100 test substitute for the template bleeding time in routine clinical practice?

The bleeding time (BT) is widely used in clinical medicine as a screening test of platelet function, although its deficiencies in such a role are well recognized. The Platelet Function Analyzer (PFA)®-100 measures the ability of platelets activated in a high-shear environment to occlude an aperture in a membrane treated with collagen and epinephrine (CEPI) or collagen and ADP (CADP). The time taken for flow across the membrane to stop (closure time) is recorded. This study compared the PFA®-100 with the BT as a screening test of platelet dysfunction in 113 hospital inpatients. The PFA®-100 test was performed initially using the CEPI cartridge; CADP tests were performed on those with abnormal (> 163_s) CEPI closure times. Whole blood platelet aggregation studies and chart review were performed on patients in whom the BT and PFA®-100 results did not agree. Abnormal bleeding times and PFA®-100 results were obtained in 20.4% and 35.4% of patients, respectively. The results of BT and PFA®-100 agreed in 74.3% of patients. Of the 29 patients in whom the BT and PFA®-100 results were discordant, whole blood platelet aggregation studies supported the PFA®-100 result in 25 (86.2%). The PFA®-100 was more sensitive to aspirin-induced platelet dysfunction and was more rapidly and cheaply performed than the BT. Since the PFA®-100 test reflects platelet function better than the BT, we conclude that this test could replace the BT as a first-line screening test for platelet dysfunction in clinical practice.     

Correlation of transient elastography with APRI and FIB‐4 in a cohort of patients with congenital bleeding disorders and HCV or HIV/HCV coinfection

Summary. Patients with inherited bleeding disorders frequently suffer from chronic hepatitis C virus (HCV) mono‐ or human immunodeficiency virus (HIV)/HCV coinfection. Non‐invasive markers for liver fibrosis are warranted for these patients. We tested a large cohort of haemophilic patients with HCV mono‐ or HIV/HCV coinfection for correlation of transient elastography (TE) with two simple surrogate markers of liver fibrosis and for differences in fibrosis stages according to these markers. We prospectively enrolled HCV‐positive patients with congenital bleeding disorders with or without HIV coinfection. Liver function tests and platelet counts were determined and TE was performed. Aspartate aminotransferase‐to‐platelet ratio index (APRI) and a simple index called FIB‐4 were calculated and results were correlated with TE. A total number of 174 patients were included (23% HCV, 36% HIV/HCV coinfected, 33% with cleared HCV and 8% with ongoing HIV but cleared HCV). TE correlated significantly with APRI and FIB‐4 (r = 0.60; P < 0.001 and r = 0.54; P < 0.001 respectively). This correlation was pronounced in patients with ongoing HCV infection (r = 0.67; P < 0.001 and r = 0.60; P < 0.001). Prediction of advanced fibrosis resulted in concordance rates >80% with combinations of TE plus APRI and APRI plus FIB‐4. HIV/HCV coinfected patients did not present with advanced fibrosis stages when compared with HCV‐monoinfected patients. Combinations of two non‐invasive markers may significantly reduce the number of liver biopsies in patients with bleeding disorders and advanced liver fibrosis. Furthermore, our data support previous studies that observed a favourable outcome in patients with HIV/HCV and a preserved immune function in times of highly active antiretroviral therapy.     

An ultrapure plasma‐derived monoclonal antibody‐purified factor IX concentrate (Nonafact®), results of phase III and IV clinical studies

Summary. Nonafact^®, an ultrapure, monoclonal antibody‐purified factor IX concentrate (FIX) was developed to minimize risk of thrombotic complications and viral transmission. To investigate the pharmacokinetics, efficacy and safety, phase III/IV studies were performed in the Netherlands and Poland from 1996 to 2007. The mean half‐life, in vivo response and recovery of Nonafact^® were 18.7 (SD 2.0) h, 1.1 (SD 0.2) IU dL^?1 per IU kg^?1 b.w. of FIX infused and 49% (SD 10%), respectively. Eleven surgical procedures were performed in eight patients. During two surgeries, both high‐risk, blood loss was observed. No postoperative bleeding occurred. The in vivo recovery of FIX was higher than expected. In the phase III follow‐up study, 26 previously treated patients (PTP) were included with a median follow‐up of 1130 days. From the 1617 minor bleedings, 80.5% was stopped after a single infusion. In the phase IV study thirteen patients were treated for a median study period of 737 days. In the two follow‐up studies the investigators rated the effect of Nonafact^® as excellent/good in 95% of major bleedings. Surgeries for which Nonafact^® was given prophylactically were without bleeding problems. In total more than 10 million units of Nonafact^® were used during almost 120 person‐years. Only one minor adverse event was reported. No inhibitors, viral transmissions and thrombogenic events occurred. In conclusion, Nonafact^® is safe and provides excellent haemostasis in haemophilia B patients treated for spontaneous bleeding or undergoing surgical procedures. Due to the excellent in vivo recovery characteristic, treatment with Nonafact^® is cost saving compared to other FIX products.     

Clinical utility of closure times using the platelet function analyzer‐100/200

The “platelet function analyzer” (PFA)?100 was first introduced to us in 1995. Since then, the instrument has appeared in over 50 reviews and almost 1000 publications. Recently, the PFA‐100 has been “upgraded” to the PFA‐200, which has transformed the user interface and electronic management, but retained the fundamental mechanics, and essentially provides the same results. The PFA‐100/200 has conceivable clinical utility to screen for von Willebrand Disease (VWD) and platelet disorders, and in monitoring desmopressin (DDAVP) therapy in both, and possibly anti‐platelet therapy. Its great strengths are its usage simplicity and sensitivity to conditions affecting primary hemostasis. However, as a “global” test, its limitation is that closure time (CT) test results are neither predictive of, nor specific for, any individual disorder. However, utilized properly, the PFA‐100/200 reflects a valuable addition to hemostasis laboratories involved in identification or therapeutic‐monitoring of disorders of primary hemostasis.