Atrial fibrillation in patients with haemophilia: a cross‐sectional evaluation in Europe

Atrial fibrillation (AF) is a common health problem in the general population, but data on prevalence or management in patients with haemophilia (PWH) are lacking. The aims of this study were to analyse the prevalence of AF and risk factors for stroke using a cross‐sectional pan‐European design and to document current anticoagulation practice. The ADVANCE Working Group consists of members from 14 European haemophilia centres. Each centre retrieved data on their PWH with AF. From the total of 3952 adult PWH, 33 had AF with a mean age of 69 years (IQR 62–76). Haemophilia was severe in seven (21%), moderate in six (18%) and mild in 20 (61%) patients. The overall AF prevalence was 0.84% and increased with age; 0.42% in patients 40–60 years and 3.4% in patients >60 years. The mean CHA₂DS₂‐Vasc score was 1.3 (range 0–4), predominantly determined by age and hypertension. Hypertension was reported in 48% of PWH with AF. In 11 patients (33%), anticoagulation was started of whom nine aspirin and two vitamin K antagonists. Of these 11 patients, nine had mild haemophilia. Anticoagulation was given in 42% of patients with a CHA₂DS₂‐Vasc score ≥2. During follow‐up (mean 57 months), there were no thrombotic events reported, nor increases in bleeding severity. The prevalence of AF in haemophilia increases with age and is predominantly present in mild haemophilia. PWH have a low stroke risk based on their CHA₂DS₂‐Vasc scores, that might be even lower considering the hypocoagulable state. Only 33% of PWH with AF receives any form of anticoagulation therapy.     

Circumcision and complications in patients with haemophilia in southern part of Turkey: Çukurova experience

Summary. Circumcision is the oldest and most frequent surgical procedure in the world and especially in Turkey as is seen in the other Islamic countries because of religious and traditional pressures. In this study, we aim to report the experience of circumcision at Çukurova University in a total of 76 patients with haemophilia between 1990 and 2011. We retrospectively reviewed medical records of 69 haemophilia patients without inhibitors and seven haemophilia patients with inhibitors who had been circumcised. Before the year 2000, factor concentrates were given before and after circumcision for 6–7 days. After 2000, we used fibrin glue together with factor concentrates for only 3 days. By‐passing agents were used for circumcision in haemophilia patients with inhibitors. Twelve of 69 patients without inhibitors were referred to our centre with bleeding after the circumcision before diagnosis of haemophilia. Nine of these twelve patients had severe life threatening bleeding and three of them had moderate bleeding. Sixty‐four patients with haemophilia were circumcised in our centre under general anaesthesia except for three patients who were given local anaesthesia. Thirteen of 57 haemophilia patients (22.8%) without inhibitors had seven mild and six moderate bleeding complications. A few patients had significant bleeding, despite adequate factor replacement. Five of seven haemophilia patients with inhibitors had two moderate and three mild bleeding complications. Our experience showed that circumcision for patients with haemophilia should be carefully performed by surgeons together with paediatric haematologist, under appropriate conditions in haemophilia centres which has comprehensive coagulation lab.     

Knowledge of disease and adherence in adult patients with haemophilia

Summary. Patients with moderate and severe haemophilia are evaluated on a regular basis at their haemophilia centres but patients with mild haemophilia are seen less often because of fewer problems related to their disease. The needs of patients with milder forms of haemophilia, however, are often underestimated, both by the patient and staff at healthcare facilities. This study evaluated the knowledge of disease and adherence to treatment among patients with severe, moderate and mild haemophilia. This was a prospective multicentre study performed in Haemophilia Centres in Scandinavia. A total of 413 (67%) of 612 patients aged >25 years with mild, moderate and severe haemophilia completed a self‐administered questionnaire. The mean age of the respondents was 49.7 years (range 25–87 years). Of the 413 respondents, 150 had a mild, 86 had a moderate and 177 had a severe form of haemophilia. A total of 22 (5%) patients did not know the severity of their disease, and 230 (56%) patients knew the effect of factor concentrate in the blood. Of the 413 respondents, 53 (13%) of the cohort never treated a haemorrhage. Patients with mild haemophilia, P ≤ 0.001, were the least likely to treat a haemorrhage. The relative number of patients who were afraid of virus transmission by factor concentrate was about similar in the three groups, 27% of those with severe haemophilia, 26% with moderate and 24% with mild haemophilia. This study shows that the amount of knowledge among haemophilia patients about their disease and treatment is somewhat limited, and demonstrates the importance of continually providing information about haemophilia and treatment, especially to patients with a mild form of the disease.     

Clinical outcome of moderate haemophilia compared with severe and mild haemophilia

Summary.  Information on outcome and treatment of patients with moderate haemophilia is scarce. In this study, we compared self-reported burden of disease in moderate haemophilia to severe and mild haemophilia. A nationwide questionnaire on bleeding pattern, treatment, impairment and quality of life was sent to 1567 Dutch patients with haemophilia. Out of 1066 respondents (response rate: 68%), 16% had moderate, 44% severe and 39% mild haemophilia. Median age was 36 years. Although overall outcome in moderate haemophilia was in between severe and mild haemophilia, moderate haemophilia patients did report a substantial burden of disease. The majority of patients with moderate haemophilia (73%) reported bleeds in the previous year; and a considerable proportion of moderate patients reported joint impairment (43%), chronic pain (15%), needed orthopaedic aids (24%) or were unemployed because of disability (27%). Within the group of moderate haemophilia patients, a large variation in bleeding pattern and outcome was observed. A quarter of patients with moderate haemophilia reported a more severe phenotype and intermittent use of prophylaxis. These patients reported frequent bleeding, with a median of eight bleeds per year, including two joint bleeds, and 68% reported joint impairment. In conclusion: Although outcome in moderate haemophilia is generally in between severe and mild haemophilia, moderate haemophilia patients reported a substantial burden of disease, and for more than 25% of patients with moderate haemophilia long term prophylaxis was implemented because of frequent bleeds.     

Pseudotumour in von Willebrand disease

Pseudotumour is a rare complication of haemophilia; it has previously been reported in patients with moderate or severe haemophilia and rarely in mild disease. We report a case of a proximal pseudotumour occurring in a 36-year-old patient with mild von Willebrand disease (vWD) who made a good recovery with conservative management. Surgery has been advocated as the optimal treatment for proximal pseudotumours due to the risk of continued bleeding and progression. However, in mild haemophilia or vWD, where the risk of spontaneous bleeds is low, conservative management may be an appropriate alternative.     

Assessment of menstrual blood loss and gynaecological problems in patients with inherited bleeding disorders

Menstrual blood loss and gynaecological problems in patients with inherited bleeding disorders were assessed in this study. One hundred and sixteen women, including 66 with von Willebrand's disease (vWD), 30 carriers of haemophilia and 20 with factor XI (FXI) deficiency were interviewed and their gynaecological history obtained. Their case records were also reviewed and menstrual loss was objectively assessed using a pictorial blood assessment chart (PBAC). Comparison with an age-matched control group (69 women) was performed. Menorrhagia (PBAC score> 100) was confirmed in 74%, 57% and 59% of women with vWD, carriers of haemophilia and FXI deficiency, respectively, in comparison with 29% in the control group (P = 0.001). PBAC scores were higher in vWD patients with a von Willebrand factor activity (vWF:Ac) of 相似文献   

Potential role of the dynamic properties of whole blood coagulation in assessment of dosage requirements in haemophilia

In the clinical setting, patients suffering from haemophilia are classified according to the residual level of the deficient coagulation factor. Patients suffering from the severe form of haemophilia (critical factor level <0.01 IU mL-1) display some heterogeneity in their tendency to bleeding despite the uniform factor level. Utilizing a new thrombelastographic method in which coagulation is activated by very small amounts of tissue factor and where resulting data are processed with new software, we studied the whole blood coagulation profile in 11 patients with severe haemophilia A and 11 patients with moderate haemophilia. In both groups of patients, we found a considerable degree of heterogeneity in the coagulation signal. In moderate haemophilia with factor VIII (FVIII):C levels between 0.01 and 0.05 IU mL-1, variance was expected, whereas a quite substantial diversity had not been forecasted in patterns of the whole blood coagulation profiles in patients with the severe form of haemophilia A. Ex vivo substitution to patient's blood to reach various theoretical levels of recombinant factor VIII (rFVIII) revealed that the coagulation response to FVIII supplementation varied substantially. In some severely affected patients levels of FVIII:C close to 0.05 IU mL-1 was sufficient to normalize the coagulation profile, while others required a dose giving >0.50 IU mL-1 of FVIII to achieve a normal whole blood clotting profile. In conclusion, our study revealed that severe haemophilia A seems not to be a single entity, but rather several different clinical and biochemical phenotypes, and that the response to added FVIII varies amongst patients.     

Haemophilia Experiences,Results and Opportunities (HERO) Study: survey methodology and population demographics

Psychosocial factors have a significant impact on the quality of life of persons with haemophilia (PWH). The Haemophilia Experiences, Results and Opportunities (HERO) initiative was developed to provide a greater understanding of the psychological components which influence the lives of PWH. This article describes the HERO methodology and the characteristics of respondents. Two online surveys (one for adult PWH ≥18 years and one for parents of children <18 years with haemophilia) were developed by an international advisory board and conducted in 10 countries. The surveys included demographic and treatment characteristics, relationships, sexual intimacy, quality of life, barriers to treatment and sources of information. A total of 675 PWH [age, median (range) 36 (18–86 years)] and 561 parents [39 (23–68 years)] completed the survey. PWH/parents reported haemophilia A (74%/76%), B (13%/16%) or with inhibitors (13%/8%). Spontaneous joint bleeding was reported in 76%/52% of PWH/children with haemophilia A, 67%/47% with haemophilia B and 93%/76% with inhibitors. Median number of bleeds (interquartile range) was 7 (2–20) for PWH and 4 (2–10) for children in the past year. Most PWH and children were treated with factor concentrate. PWH reported arthritis (49%) and HIV/HCV infections (18%/43%) related to haemophilia. Most PWH and parent respondents had received formal education (85%/89%) and were employed full‐ or part‐time (60%/72%). HERO is one of the largest multinational studies focused on psychosocial issues in haemophilia, including historical and treatment information that will allow for multivariate analyses of determinants of health in haemophilia.     

Bone health in persons with haemophilia: a review

Bone density is a measure of equilibrium between bone formation and bone resorption; any imbalance in these two processes might lead to osteopenia and osteoporosis. Osteoporosis in general has been considered to be an important cause of morbidity in both men and women and more so in haemophilia and other bleeding disorders. Specific triggering factors in persons with haemophilia (PWH) are abnormal liver function because of viral infection, bleeding and inflammation, lack of physical and athletic activities, low body weight and others. Although the pathogenesis of osteoporosis is not clear, it has been considered as a severe comorbidity in PWH in both developing and developed countries. This is more evident in developing countries where there is no free access to factor concentrates, and primary prophylaxis is beyond the reach of vast majority of the patients. Only few references are available in the literature on the prevalence and management of osteoporosis in haemophilia population. This review summarises the prevalence, plausible mechanisms and management options of this important morbidity in PWH.     

Prevalence of factor IX inhibitors among patients with haemophilia B: results of a large-scale North American survey

Summary. This survey provides new information on the severity of factor IX deficiencies among patients being treated for haemophilia B and on the prevalence of factor IX inhibitors in this population. A questionnaire was sent to 150 haemophilia treatment centres in the United States and Canada. 82 centres responded and provided data on 1967 patients with haemophilia B. 37% of these patients had severe haemophilia B (<1% of the normal level of factor IX), 33% had moderate haemophilia B (1–5% of the normal level of factor IX), and 30% had mild haemophilia B (>5% of the normal level of factor IX). Only 29 (1.5%) of the patients had factor IX inhibitors; 28 of these patients (96.6%) had severe haemophilia B, and one of these patients (3.4%) had moderate haemophilia B. Factor IX inhibitor titres were 0.6–1 Bethesda unit (BU) in seven patients, > 1–5 BU in four patients, > 5–10 BU in one patient, and > 10 BU in 17 patients. Factor IX inhibitors are much less common in patients with haemophilia B than in patients with haemophilia A.     

The use of a co‐design model in improving timely bleed reporting by adults with haemophilia living in the Auckland region of New Zealand

Many adult patients diagnosed with phenotypically moderate and severe haemophilia living in the Auckland region of New Zealand do not report bleeding episodes within a timeframe that allows for optimal assessment and management. This can result in poor clinical outcomes for patients and poor oversight of the use of expensive clotting factor concentrates. Our goal was to improve both the number and speed at which bleeding episodes were reported to our centre, improving access to care and clinical oversight of the use of expensive factor concentrates and aiding the development of a care partnership with patients. We worked with 70 adult PWH living in the Auckland region of New Zealand with moderate and severe haemophilia A and B. Over a 5‐month period between March and July 2013 we used a co‐design model to develop and implement a range of strategies to improve the timing and frequency of bleed reporting. Mean bleed reporting time was reduced threefold, with a threefold increase in the number of bleeds reported per month. We reduced the number of bleeding episodes reported outside of a prespecified 48‐h time limit by 68%. We significantly improved bleed reporting and time to report, indicating improved access to our services, improved clinical oversight and improved accountability to our national funder. We have achieved a care partnership and a reduction in factor consumption for the study population without compromising the quality of care they receive.     

Cancer detection and management in patients with haemophilia: a retrospective European multicentre study

Lymphomas or hepatocarcinomas related to blood‐borne transmitted diseases are well‐known malignancies in persons with haemophilia (PWH). However, rising life expectancy has increased the number of PWH suffering from other malignancies. This study aimed to collect cancer occurrence data in PWH followed in five European haemophilia treatment centres (Brussels, Geneva, Marseille, Montpellier and Paris‐Bicêtre) over the last 10 years and to analyse some particular features of cancer occurring in PWH. In total, 45 malignancies were diagnosed in 1067 PWH. The most common malignancies were hepatocellular carcinoma (12/45) and urogenital tract tumours (9/45). Bleeding at presentation or changes in bleeding pattern was indicative of cancer in four patients. Three patients with mild haemophilia developed anti‐factor VIII inhibitors after intensive substitution therapy prior to surgery or invasive procedures. There was no bleeding associated with chemotherapy or radiotherapy. A few bleeding complications occurred following invasive (3/39) or surgical procedures (2/27) as a result of insufficient hemostatic coverage or in spite of adequate substitution. No bleeding was noted after liver or prostate biopsies. Following cancer diagnosis, five patients were switched from on‐demand to prolonged prophylaxis substitution. In the majority of cases, the standard cancer treatment protocol was not modified on account of concomitant haemophilia. Thus, oncological treatments are not contraindicated and should not be withheld in PWH assuming that adequate haemostasis correction is undertaken. As shown by our study results, a change in bleeding pattern in adult PWH should raise suspicion of a malignancy. Intensive substitution must be considered a risk factor for inhibitor development.     

High-titre factor VIII inhibitor in two children with mild haemophilia A

A frequently encountered complication of therapy given to patients with severe haemophilia A is the development of antibodies to infused factor VIII. While much less common, inhibitors also occur in patients with mild or moderate severity haemophilia A. Often thought to be of low titre and transient, several cases of high-titre inhibitors have been described in patients with mild or moderate haemophilia A. Generally these occur in adults or adolescents following significant infused factor VIII exposure. A review of reported cases revealed only two cases of high-titre inhibitor formation in mild haemophilia A patients younger than 10 years of age. We wish to report our experience with an additional two children with mild haemophilia A and high titre inhibitors, and offer suggestions for the management of these children.     

Quality of life during menstruation in patients with inherited bleeding disorders

Menorrhagia is a common and major problem for patients with inherited bleeding disorders, especially vWD. Quality of life during menstruation was assessed in 99 patients with inherited bleeding disorders including vWD (n = 57), carriers of haemophilia A (n = 17), carriers of haemophilia B (n = 7) and FXI deficiency (n = 18), and comparison was performed with an age-matched control group (n = 69). A questionnaire was used that included four main sections: (i) general health, (ii) health and daily activities, (iii) dysmenorrhea and (iv) quality of life during the menstrual period. Although patients with inherited bleeding disorders felt that their health (in general) was very good, they had significantly poorer quality of life on all the scales used than controls. Thirty-nine per cent reported having cut down on the amount of time spent on work and other activities as a result of their menstruation; 47% felt that they accomplished less than they would like during this period, 38% felt that they were limited in the kind of work and other activities that they could do, and 40% found that it took extra effort to perform their work. Fifty-one per cent experienced moderate, severe or very severe dysmenorrhoea. Quality of life was statistically poorer in patients with vWD, menstrual scores > 100 according to the pictorial blood assessment chart (PBAC), those who had periods > or = 8 days and those who experienced flooding or passage of clots. In conclusion, menstruation has a negative effect on the quality of life in patients with inherited bleeding disorders especially in those with objectively confirmed menorrhagia.     

Risk assessment for coronary heart disease in patients with haemophilia: a single centre study in the United States

In haemophilia, coronary heart disease (CHD) occurs at a similar frequency as in the general population, but the contributing risk factors in haemophilia are incompletely understood. To investigate risk factors and 10‐year CHD risk in a single centre cohort of patients with haemophilia (PWH) ≥20 years old (n = 89). We retrospectively applied the modified Framingham National Cholesterol Education Program/Adult Treatment Panel (NCEP/ATP) III risk prediction equation. Three risk levels were defined: <10% (low), 10–20% (intermediate) and >20% (high). Results were compared to the National Health and Nutrition Examination Survey (NHANES). Mean age in both cohorts was similar. Compared to NHANES, systolic blood pressures were significantly higher in PWH, but current smoking and cholesterol were lower. CHD risk differed significantly between PWH and NHANES (P = 0.005) with a higher proportion of PWH classified at low risk (77.5% vs. 61.0%). The proportion of low risk patients was also significantly higher for severe haemophilia patients compared to non‐severe haemophilia patients (88.6% vs. 66.7%, P = 0.02). Among PWH, and compared to PWH who were hepatitis C (HepC) negative, HepC positive patients had significantly lower cholesterol, LDL and triglycerides. The CHD risk of HepC positive patients differed significantly from NHANES (P = 0.03) with a lower proportion of HepC positives being classified as high risk (5.7% vs. 17.3%). Favourable CHD risk classification in PWH may be influenced by low cholesterol associated with HepC infection. Estimates of CHD risk in PWH by composite scoring may not be accurate and will require studies correlating risk factors with incident CHD.     

Prevalence of inhibitor formation in a cohort of haemophilic children exposed to several products of various purities

Summary . To evaluate the frequency and potency of inhibitor formation based on the product used, we retrospectively reviewed the records of 99 children with various types and severity of haemophilia (haemophilia A 82, severe 46; haemophilia B 10, severe 6; vWD 7) treated for the last 20 years. After a mean observation period of 8 years an overall of 23 patients (23.2'/0) developed an inhibitor (haernophilia A 26.8%; severe 4O%, moderate 20%, mild 3.8%). None of the haemophilia B patients presented with an inhibitor, and only one child with bevere vWD (1/7, 14.3%) showed a transient inhibitor under cryoprecipitate therapy. Inhibitor titre was low (< 5 BU) in most cases (91.3%) and in only two patients (8.75%) was 6 and 8 BU respectively. Antibodies to FVIII were transient (detected only once) in four (17.4%) and intermittent in 19 patients (82.6%). By the age of 12 years, 17/23 patients (73.9%) had demonstrated an inhibitor. The inhibitor detection seemed to be higher in the groups of patients exposed to monoclonal (3115, 20%), SID-treated (10159, 16.9%) or H/T FVIII concentrates (6/41, 14.6%), compared to groups of patients who received cryo/plasma (9.5%) or unmodified concentrates (5.1%); nevertheless the differences were not statistically significant.
Surprisingly, none of the 52 patients who received a S/D + chromatography-treated factor VIIl concentrate developed an inhibitor after a mean observation period of 1.7 years (range 0.2–2 years). The overall prevalence of inhibitor formation in previously untreated haemophiliacs was 14.3% (4/28), irrespective of the product used.
Our data indicate that a high proportion of our haemophilic children exposed to several products of various purities have developed a low-titre inhibitor which in most cases was transient or intermittent. However, despite the presence of the antibody, none of the patients needed a change in the mode of treatment.     

A case–control study assessing bone mineral density in severe haemophilia A in the UK

It has been shown that bone mineral density (BMD) may be lower in patients with haemophilia (PWH). A comparison to control subjects is required to thoroughly assess current BMD in PWH in the UK. The objective of this study was to test the hypothesis that BMD is lower in PWH than in controls, and in patients with more severely affected joints or lower activity levels. In this case–control study, 37 patients with severe haemophilia A were recruited from two haemophilia centres in the UK. A group of 37 age, gender and ethnicity‐matched control participants were recruited. All participants had a bone density scan, a musculoskeletal assessment, a blood test for vitamin D and completed a functional activity questionnaire. Of the case group, 5% had osteoporosis and 24% had BMD lower than expected for age. No control participants had osteoporosis, 3% had osteopenia and 14% had BMD lower than expected for age. Ninety one per cent of case participants and 92% of control participants had reduced 25(OH)D levels. Case participants had significantly lower BMD than control participants, and case participants with more severely affected joints, lower activity levels, HIV, history of hepatitis C or lower BMI had significantly lower BMD. Patients with severe haemophilia have a higher risk of low BMD than men without haemophilia. Patients with more severely affected joints and lower activity levels have lower BMD. It remains unclear whether patients with low BMD reached adequate peak bone mass. Low vitamin D may be present in the majority of PWH.     

Assay discrepancy in mild haemophilia A: entire population study in a National Haemophilia Centre

Summary.  Assay discrepancy in mild haemophilia, here defined by a significantly higher factor VIII (FVIII):C response by the one-stage procoagulant assay as compared with a two-stage enzymatic method, has repeatedly been reported in literature. The purpose of this study was to determine the overall prevalence of this phenomenon amongst mild haemophilia families from a population of 2.95 million inhabitants in the Western Danish region. Information was collected retrospectively through a thorough search of archives of the National Haemophilia Centre in Aarhus. We identified 109 patients with mild haemophilia A amongst whom 92 were eligible to enter the study. These represent a total of 53 unrelated families. Our data illustrate that this assay discrepancy pattern is found quite frequently amongst our mild haemophilia A families. While the ratio of FVIII:C chromogenic/FVIII:C clot values was quite consistent amongst patients belonging to same family pattern, ratios in the entire cohort of families ranged from 0.18 to 1.00. Selecting a cut-off level for the FVIII:C chromogenic/FVIII:C clot ratios at 0.7, 0.6 and 0.5, respectively, we found that 38 (72%), 27 (51%) and 19 (36%) of families, respectively, displayed this assay discrepancy. In 10 patients, the FVIII:C chromogenic level was inside the category of moderate haemophilia at >0.01–<0.05 IU mL⁻¹, pointing to a class-shift in the biochemical phenotype. In conclusion, our data illustrate a substantial prevalence of the assay discrepancy phenomenon amongst mild haemophilia A patients in our geographical area.     

Prevalence and risk factors of cardiovascular disease (CVD) events among patients with haemophilia: experience of a single haemophilia treatment centre in the United States (US)

Summary. The primary objective of the study was to examine the prevalence of cardiovascular disease (CVD) events and their known risk factors among persons with haemophilia (PWH). This cross‐sectional study, covering a 5‐year period, included PWH aged ≥35 years who were cared for at a single haemophilia treatment centre in the United States. Medical records were extensively reviewed to collect the information about CVD events and their risk factors such as obesity, hypertension, diabetes, hypercholesterolemia and smoking. Prevalence rates were compared with national population estimates and associations between risk factors and CVD events were examined using logistic regression. The study cohort comprised 185 PWH (102 haemophilia A and 83 haemophilia B). Lifetime prevalence of a CVD event was 19.5% (36/185, 95% confidence interval [CI] 13.8–25.2%). CVD mortality was 5.4% (10/185, 95% CI 2.7–8.1). Compared with US non‐Hispanic White males (NHWH), PWH had about twice the prevalence of coronary artery disease, stroke and myocardial infarction. The prevalence of CVD risk factors for PWH was similar to that for US NHWM with 39.5% of PWH exposed to two or more of these risk factors. Both hypertension and smoking were associated significantly with CVD events, with odds ratios of 4.9 and 6.3, respectively. In conclusion, this study revealed that both CVD events and its risk factors were at least equally prevalent among PWH and might have been even higher than among the US NHWM in the United States. Therefore, it is imperative to implement strategies for CVD prevention among PWH.     

Laboratory diagnosis of von Willebrand disorder (vWD) and monitoring of DDAVP therapy: efficacy of the PFA-100® and vWF:CBA as combined diagnostic strategies

We have coevaluated a combination of test processes for diagnosing von Willebrand disease (vWD) and monitoring deamino-delta-D-arginine vasopressin (DDAVP) therapy. Using normal controls (n = 23), closure time (CT) ranges measured by PFA-100(R) were (mean +/- 2SD): (i) collagen/ADP cartridge (C/ADP): 67-127 s (ii) collagen/epinephrine (C/Epi): 94-162 s. From a panel of 125 patients undergoing evaluation for clinical haemostatic defects, 29/30 samples from patients with vWD [17/18 type 1, 1/1 type 3, 3/3 type 2A, 7/7 type 2B and 1/1 pseudo-vWD] gave prolonged CTs using C/Epi. The C/ADP was less sensitive, being normal in 7/18 of the type 1 vWD individuals, with higher sensitivity to more severe vWD. Individuals with haemophilia (six factor VIII-deficient, one factor XI-deficient) gave normal CTs, while those with clinical thrombocytopenia (n=13) gave normal or prolonged CTs, somewhat dependent on platelet count. The PFA-100 was also evaluated as a part of the laboratory monitoring procedure in patients with either vWD or haemophilia undergoing a DDAVP trial as a therapeutic management process. For vWD, correction of an initially prolonged CT by DDAVP, accompanied by normalization of von Willebrand factor (vWF) measurable by von Willebrand factor antigen, vWF collagen binding activity and vWF ristocetin cofactor assays (vWF:Ag, vWF:CBA and vWF:RCof), was achieved in type 1 vWD (n=5). In an individual with type 2A vWD, DDAVP normalized vWF:Ag and vWF:RCof, but had no apparent effect on the baseline maximally prolonged CT. In an individual with type 2B vWD, factor VIII/vWF concentrate also normalized vWF:Ag and vWF:RCof, but similarly had no apparent effect on the baseline maximally prolonged CT. vWF:CBA did not normalize for either of these individuals, potentially suggesting that normalization of vWF:CBA might be required for normalization of CT. This concept is supported by correlation analysis undertaken between CT and various vWF parameters. Among these, vWF:CBA held the strongest relationship in our data set, which showed an inverse progressive rise in CT for falling vWF:CBA. Based on these results, we would conclude that the PFA-100 is highly sensitive to the presence of vWD, and may thus provide a valuable screening test for vWD. Furthermore, the combined utility of the PFA-100 and vWF:CBA as markers of DDAVP responsiveness may prove to be simple, quick but powerful, predictors for its clinical efficacy.