Margaret E. Rick

von Willebrand disease (VWD): evidence-based diagnosis and management guidelines, the National Heart, Lung, and Blood Institute (NHLBI) Expert Panel report (USA)†

Summary.  von Willebrand disease (VWD) is a commonly encountered inherited bleeding disorder affecting both males and females, causing mucous membrane and skin bleeding symptoms, and bleeding with surgical or other haemostatic challenges. VWD may be disproportionately symptomatic in women of child‐bearing age. It may also occur less frequently as an acquired disorder (acquired von Willebrand syndrome). VWD is caused by deficiency or dysfunction of von Willebrand factor (VWF), a plasma protein that mediates platelet haemostatic function and stabilizes blood coagulation factor VIII. The pathophysiology, classification, diagnosis and management of VWD are relatively complex, but understanding them is important for proper diagnosis and management of patients with VWD. These evidence‐based guidelines for diagnosis and management of VWD from the National Heart, Lung, and Blood Institute (NHLBI) Expert Panel (USA) review relevant publications, summarize current understanding of VWD pathophysiology and classification, and present consensus diagnostic and management recommendations based on analysis of the literature and expert opinion. They also suggest an approach for clinical and laboratory evaluation of individuals with bleeding symptoms, history of bleeding or conditions associated with increased bleeding risk. This document summarizes needs for further research in VWF, VWD and bleeding disorders, including clinical research to obtain more objective information about bleeding symptoms, advancements in diagnostic and therapeutic tools, and enhancement in the education and training of clinicians and scientists in bleeding and thrombotic disorders. The NHLBI Web site (http://www.nhlbi.nih.gov/guidelines/vwd) has a more detailed document, a synopsis of these recommendations, and patient education information.

High Prevalence of Osteonecrosis of the Femoral Head in HIV-Infected Adults

Context Osteonecrosis (avascular necrosis) of the hip is an uncommon but painful and disabling condition that sometimes requires total hip replacement. Contribution This large survey showed that an unusually high percentage of HIV-infected adults (4.4% [95% CI, 2.5% to 7.2%]) had osteonecrosis of the hip, as detected by magnetic resonance imaging. Implications Although screening asymptomatic HIV-infected patients is not warranted, osteonecrosis should be considered in HIV-infected patients with persistent groin or hip pain. The Editors The natural history of HIV infection has changed substantially with the wide use of highly active antiretroviral regimens that include potent protease inhibitors or non-nucleoside reverse transcriptase inhibitors (1). The incidence of HIV-related deaths and HIV-associated opportunistic infections has decreased dramatically. As survival and quality of life have improved, the focus of health care providers has shifted to management of the increasingly complex drug regimens and their associated drug interactions and toxicities. Previously unrecognized or underrecognized complications related to HIV infection or therapies for HIV infection, such as lactic acidosis, hyperlipidemia, and fat redistribution, are increasingly being recognized (2). Osteonecrosis of the hip (also known as avascular necrosis) is a disabling condition that frequently requires total hip replacement (3-5). Osteonecrosis in HIV-infected patients was first reported in 1990 (6). Subsequent anecdotal reports have suggested that osteonecrosis is being diagnosed with increasing frequency in the setting of HIV infection (7-31). Between May 1999 and November 2000, six HIV-infected patients followed at the Warren Grant Magnuson Clinical Center of the U.S. National Institutes of Health (NIH) presented with groin or hip pain and received a diagnosis of osteonecrosis. The first two of these patients received their diagnosis within a 4-day period and were the first HIV-infected patients ever to receive such a diagnosis at the NIH Clinical Center. We also learned that an increasing number of cases of osteonecrosis were being reported to the U.S. Food and Drug Administrations Adverse Event Reporting System. We were concerned that osteonecrosis might be becoming a major HIV-related complication. We hypothesized that, if this were true, additional patients may have developed clinically silent osteonecrosis. Because magnetic resonance imaging (MRI) has been used to study asymptomatic osteonecrosis of the hip in other high-risk populations (32-37), we undertook a prospective MRI-based study to determine the prevalence of and evaluate possible risk factors for asymptomatic osteonecrosis of the hip in a sample of HIV-infected patients. Methods Participant Recruitment and Questionnaire Between 1 June and 15 December 1999, adults who were enrolled in studies of the treatment or natural history of HIV infection at the NIH Clinical Center or who were receiving health care services at the National Naval Medical Center in Bethesda, Maryland, were invited to participate in an MRI-based screening study of osteonecrosis of the hip. All patients seen in the outpatient clinics of the National Institute of Allergy and Infectious DiseasesNIH Clinical Center HIV program during the study period were informed of the protocol and encouraged to participate. Because this study focused on asymptomatic patients, we excluded persons with current groin or hip pain. Because the incidence of osteonecrosis was unknown, we considered several possible sample sizes (100 to 300 patients) and estimations of the 95% CI for low prevalence rates of asymptomatic osteonecrosis (0.1% to 3.5%). We determined that a sample size of at least 300 HIV-infected participants would be reasonable and attainable. Before undergoing MRI, participants completed a standard questionnaire on joint symptoms; medical history; medication use; and personal habits, including ethanol use, cigarette smoking, and routine exercise regimens. Questions related to medication use made a clear distinction between corticosteroids and other types of steroids, such as androgenic and anabolic steroids. Patients were asked why corticosteroids were prescribed and the route, frequency, and duration of use. The Institutional Review Board of the National Institute of Allergy and Infectious Diseases approved the protocol. All participants gave written informed consent. Data Collection We retrieved laboratory and clinical data from patient databases. Laboratory values obtained within 4 months of the MRI date were used in the analyses; for certain variables, we also analyzed the highest or lowest values recorded in a laboratory database that contained data back to 1984. Physiatrist Evaluation After approximately 150 patients were scanned and asymptomatic osteonecrosis was detected in 4 patients, we prospectively determined whether subtle physical findings might identify patients with MRI evidence of osteonecrosis of the hip. Patients enrolled after 12 July 1999 were asked (but not required) to be examined by a physiatrist who was unaware of the MRI results. The examination included evaluation of range of motion in the hip, which involved testing in all planes to end range with and without resistance and joint-loading maneuvers; pain was assessed in each test (38). MRI Scanning HIV-Infected Participants Magnetic resonance imaging was performed by using an LX Horizon 1.5-T MRI system (General Electric Medical Systems, Milwaukee, Wisconsin). We modeled the protocol for screening MRI on a previously described method for bilateral screening of the hips for osteonecrosis (37). Coronal T1-weighted spin-echo sequences were done with a repetition time of 400 ms and an echo time of 8 ms (using a 256 192 matrix). These were followed by coronal fatsuppressed T2-weighted fast spin-echo inversion recovery sequences with a repetition time of 3266 ms, an echo time of 38 ms, and an inversion time of 150 ms (256 224 matrix). Other variables used for both screening sequences included three excitations, a 40.0 40.0cm field of view, and 5-mm contiguous sections. All MRI scans were initially interpreted by one of the investigators. Positive scans were later intermixed with 35 randomly selected negative scans of HIV-infected participants and were reviewed by a second radiologist, who was unaware of the previous interpretation. Patients with osteonecrosis on the screening MRI underwent dedicated high-resolution MRI of the affected hip or the more abnormal hip. HIV-Negative Participants We assumed that asymptomatic osteonecrosis of the hip detectable only by MRI must occur infrequently in healthy adult humans with no known risk factors. To document this, we recruited persons without hip or groin pain who had no known risk factors for osteonecrosis. Exclusion criteria for this comparison group were a history of alcohol abuse, hip or leg fracture, pancreatitis, diabetes mellitus, hypertriglyceridemia (requiring therapy), systemic lupus erythematosus, blood-clotting disorders, or systemic corticosteroid use during the previous year or for greater than 1 month ever (total lifetime use). We recruited these participants from an NIH healthy volunteer database and by posting flyers at the NIH Clinical Center. The participants in the comparison group were approximately matched for age and sex to participants in the screening study HIV-infected patients; the comparison group underwent the MRI screening and consented to participate using the same protocol and procedures that were used in the HIV group. Hematologic Evaluation Participants with MRI evidence of osteonecrosis were evaluated for a possible hypercoagulable state by using the following assays: two assays for the presence of a lupus anticoagulant (DRVVT, American Diagnostica, Inc., Greenwich, Connecticut, and Staclot, Diagnostica Stago, Asnieres-Sur-Seine, France); assays for immunoglobulin (Ig)G and IgM anticardiolipin antibodies (Quantilite, Innova, San Diego, California); functional assays for protein C, protein S, and antithrombin III levels (Diagnostica Stago; an assay for thrombinantithrombin complex levels [Dade Behring Marburg, Marburg, Germany]; an assay for functional plasma activator inhibitor-1 levels (Biopool, Umea, Sweden); and routine laboratory assays for serum homocysteine and serum lipoprotein(a) levels. These patients were also evaluated for genetic predisposition to hypercoagulability by using restriction enzyme-based genetic tests for factor V Leiden, a prothrombin gene abnormality (G20210A), and for the heat-labile folate reductase (5,10 methylene tetrahydrofolate reductase) gene abnormality, which may lead to hyperhomocystinemia (39-41). For a comparison group, we measured anticardiolipin antibodies, lupus anticoagulant, and protein S levels in a sample of 50 controls with HIV infection who had no evidence of osteonecrosis on MRI. These controls were randomly selected from patients who had been previously scanned as part of the study and who were seen in our clinics for routine visits over a 3-week period (19 November to 9 December 1999). Statistical Analysis We used the method of Clopper and Pearson (42) to calculate exact CIs for proportions. Associations of osteonecrosis with categorical variables were evaluated by using a two-sided Fisher exact test or, for variables with more than two categories, the FisherFreemanHalton test (43). Associations with continuous variables were evaluated by using a two-sided Wilcoxon rank-sum test with continuity correction. Confidence intervals for relative risks for osteonecrosis were estimated by using the likelihood score method (44). For CIs of odds ratios, we estimated variance according to the method of Robins and colleagues (45). For these calculations, we used the NCSS 2000 software package (Number Cruncher Statistical Systems, Kaysville, Utah) and the StatXact 4 software package (Cytel Software Corp., Cambridge, Mass

Interleukin 1 or endotoxin increases the release of von Willebrand factor from human endothelial cells

von Willebrand factor (vWF), a large adhesive glycoprotein, is synthesized by vascular endothelial cells (EC). Plasma levels of vWF manifest a broad normal range, and are elevated during sepsis and in inflammatory states. Since the inflammatory mediator, interleukin 1 (IL1) and bacterial endotoxin (LPS) both initiate procoagulant changes in vascular endothelium, we investigated the effect of these substances on endothelial cell release and residual endothelial cell content of vWF‐antigen (vWFAg). Cultured human EC exposed to either IL1 or LPS released greater amounts of vWFAg compared to control EC. The augmented release could be detected within 1–2 h after exposure to IL1 or LPS and was not inhibited by cycloheximide, suggesting that de novo protein synthesis was not required for release to occur. Residual cellular vWFAg was reciprocally lower in IL1‐ or LPS‐treated EC at 24 and 48 h, indicating that compensatory increase in synthesis of vWFAg did not occur during this time interval. Released vWF contained the higher molecular weight multimers observed in normal endothelial cells, and it possessed ristocetin cofactor activity. We propose that release of functional vWF from EC exposed to inflammatory mediators may be at a mechanism for localization of platelets and enhanced thrombogenicity at inflammatory foci.

The Incidence and Natural History of Osteonecrosis in HIV-Infected Adults

BACKGROUND Osteonecrosis is increasingly recognized as a debilitating complication of human immunodeficiency virus (HIV) infection, but the natural history has not been well described. We previously documented a high prevalence (4.4%) of magnetic resonance imaging (MRI)-documented osteonecrosis of the hip in a cohort of 339 asymptomatic HIV-infected patients. The present study was designed to determine the incidence of newly diagnosed osteonecrosis in this cohort and to describe the natural history of osteonecrosis in HIV-infected patients. METHODS Asymptomatic HIV-infected patients with a previous hip MRI negative for osteonecrosis underwent follow-up MRI. Patients with asymptomatic or symptomatic osteonecrosis were enrolled in a natural history study, which included serial MRIs and a physiotherapy follow-up. RESULTS Two hundred thirty-nine patients underwent a second MRI a median of 23 months after the initial MRI. Osteonecrosis of the femoral head was diagnosed in 3 patients (incidence, 0.65 cases per 100 person-years). During the period of January 1999 through April 2006, symptomatic hip osteonecrosis developed in 13 clinic patients (incidence, 0.26 cases per 100 person-years). Among 22 patients enrolled with symptomatic hip osteonecrosis, 18 had bilateral involvement of the femoral heads, and 7 had osteonecrosis involving other bones. Two (11%) of 18 asymptomatic patients and 13 (59%) of 22 symptomatic patients underwent total hip replacement. The percentage of involvement of the weight-bearing surface of the femoral head and the rate of progression to total hip replacement was significantly greater (P<.001) in symptomatic patients than in asymptomatic patients. CONCLUSIONS HIV-infected patients are at approximately 100-fold greater risk of developing osteonecrosis than the general population. Disease progression is slower in asymptomatic patients than in symptomatic patients. Given the high frequency of total hip replacement in symptomatic patients, studies to assess preventive and treatment strategies are essential.

Danazol Increases Factor VIII and Factor IX in Classic Hemophilia and Christmas Disease

We gave danazol (600 mg per day orally for 14 days), an attenuated androgen, to four adults with classic hemophilia and one adult with Christmas disease. The levels of factor VIII in the patients with classic hemophilia ranged from 1 to 3 per cent before treatment and rose to 3 to 8 per cent during the treatment period. The level of factor IX in the patient with Christmas disease rose from 5 to 14 per cent. The rise in clotting-factor activity was usually observed within five to six days after the initiation of therapy and peaked between 7 and 13 days. The drug had no untoward effects. During the 70 patient-days of therapy, only two patients required plasma products, each on one occasion. These data suggest that danazol therapy may decrease the hemorrhagic tendency and reduce the need for transfusions of plasma products in classic hemophilia and Christmas disease. Controlled clinical trials will be required to establish its value in these applications.

Selective serotonin reuptake inhibitors: measurement of effect on platelet function

Selective serotonin reuptake inhibitors (SSRIs) reduce platelet serotonin and are associated with increased gastrointestinal bleeding, an effect that is enhanced when taken with NSAIDs or aspirin. The best method to evaluate hemorrhagic events in patients taking SSRIs has not been determined. Platelet aggregation, which is not widely available, shows SSRI inhibition of platelet function; we tested whether a platelet function analyzer could detect SSRI inhibition of platelet function. Two groups of outpatients with mood disorders were recruited; each patient was taking a stable dose of either an SSRI or bupropion for at least 6 weeks. They were tested using the platelet function analyzer-100 (PFA-100; Dade International Inc, Miami, Fla) concomitantly with platelet aggregation. Fifty-eight patients were analyzed. We detected significant differences between the groups using aggregation methods with arachidonic acid (aggregation, P = 0.00001; release, P = 0.009) and collagen (aggregation, P = 0.016; release, P = 0.006). The PFA-100 did not detect differences between the groups or results outside the reference range. The PFA-100 does not detect the inhibitory effects of SSRIs on platelet function, but it can be used to direct evaluation of bleeding in a patient taking an SSRI. Abnormal PFA-100 results suggest additional evaluation for von Willebrand disease, other platelet inhibitory medications, or underlying intrinsic platelet dysfunction.

Circulating Heparan Sulfate Anticoagulant in a Patient with a Fatal Bleeding Disorder

We have identified a circulating, heparin-like anticoagulant in a patient with multiple myeloma (IgG4 lambda) who had serious clinically evident bleeding that contributed to his death. Purification of the patients circulating coagulation inhibitor was accomplished by ammonium sulfate concentration, anion exchange chromatography, and affinity chromatography on protamine sulfate. Analysis of the purified inhibitor showed that it was a proteoglycan that comigrated with heparan sulfate on lithium acetate-agarose-gel electrophoresis and that it contained 39 per cent L-iduronic acid. Control samples of heparan sulfate and heparin contained 29 and 68 per cent L-iduronic acid, respectively. Functional coagulation studies revealed that the purified inhibitor had cofactor activity with antithrombin III that could be abolished by prior incubation with protamine sulfate or platelet factor 4. Recognition of the existence of this or of other similar inhibitors in bleeding patients is important because of the potential for treatment with agents such as protamine sulfate and platelet factor 4, which neutralize the anticoagulant effects of proteoglycans.

Clinical and laboratory diagnosis of von Willebrand disease: A synopsis of the 2008 NHLBI/NIH guidelines

Von Willebrand factor (VWF) mediates blood platelet adhesion and accumulation at sites of blood vessel injury, and also carries coagulation factor VIII (FVIII) that is important for generating procoagulant activity. Von Willebrand disease (VWD), the most common inherited bleeding disorder, affects males and females, and reflects deficiency or defects of VWF that may also cause decreased FVIII. It may also occur less commonly as an acquired disorder (acquired von Willebrand syndrome). This article briefly summarizes selected features of the March 2008 evidence‐based clinical and laboratory diagnostic recommendations from the National Heart, Lung, and Blood Institute (NHLBI) Expert Panel for assessment for VWD or other bleeding disorders or risks. Management of VWD is also addressed in the NHLBI guidelines, but is not summarized here. The VWD guidelines are available at the NHLBI Web site (http://www.nhlbi.nih.gov/guidelines/vwd). Am. J. Hematol. 2009.

Platelet von Willebrand factor: Comparison with plasma von Willebrand factor

Platelet von Willebrand factor (vWf) was compared to its plasma counterpart. The platelet vWf was different from plasma vWf in that the multimeric organization was different, larger multimers were present, and the ratio of vWf activity to antigen was higher. Platelet and plasma vWf were similar in their antigenic reactivity in the electroimmunoassay and by liquid phase radioimmunoassay. The amount of vWf activity in large platelets was significantly higher than in normal platelets while the antigen content, although somewhat higher, was not significant. These studies show differences between normal platelet and plasma vWf, and also suggest that platelet size must be considered when platelet vWf is measured in disease states.

Diagnosis and management of von willebrand's syndrome

von Willebrands disease is the most common of the inherited bleeding disorders. It is caused by quantitative and/or qualitative abnormalities of von Willebrand factor, and it usually presents with bleeding from mucosal surfaces. The diagnosis is confirmed by measuring von Willebrand factor activity and antigen levels, factor VIII activity, and performing a multimer analysis of von Willebrand factor. Treatment may require plasma-derived concentrates, but can often be accomplished with DDAVP, a vasopressin analogue that causes transient release of von Willebrand factor from body storage sites.