The Power of Your Choice
Your choice of the IHTC Pharmacy Program directly supports your IHTC team and patient services, and activities provided to the hemophilia community. The IHTC Pharmacy Program provides savings to you and your health insurance plan.
Every patient has the right to choose their clotting factor pharmacy provider. The IHTC supports your right of choice and will assist you in making an informed decision.
- What is Von Willebrand Disease (VWD)?
- Types of VWD
- Prevalence of VWD in the US Population
- Causes of VWD
- Signs & Symptoms of VWD
- Emergency Care
- Diagnosis of VWD
- Treatment of VWD
- Treatment Adherence in VWD Care
- Hemophilia Treatment Centers and Comprehensive Care
- IHTC’s Disease Management Program: Optimizing Patient Care While Minimizing Costs
- Special Considerations
- What Can the IHTC Do for You?
What is Von Willebrand Disease (VWD)?
Von Willebrand disease (VWD) is the most common bleeding disorder in the general population, affecting males and females equally. Population screening suggests that 0.6% to 1.3% of people may be affected with some form of VWD.1 VWD is caused by shortages or alterations in a person’s Von Willebrand Factor (VWF), a large protein made up of protein subunits. VWF binds to clotting factor VIII (FVIII) and protects it from being broken down by enzymes in the blood. In the process of blood clotting, VWF also helps platelets bind to each other and to the inside lining of injured blood vessels. This forms a blood-clotting plug and eventually a stable clot that stops blood from leaking out of the injured blood vessel. When VWF is defective or in short supply, a person may have trouble forming a clot after an injury.
Types of VWD
There are several types of VWD with a variable range of severity.2Genetic alterations in the VWF gene have been identified for some of these types.
- VWD Type 1: The most common and often mildest subtype of VWD, in which VWF (and sometimes FVIII) levels are lower than normal;
- VWD Type 2: The second most common subtype, featuring structurally abnormal VWF, and resulting in moderately severe disease. Type 2 is further subdivided into types 2A, B, M, and N.
- Type 2A causes a reduction in platelet binding because of a deficiency of specific VWF subunits;
- Type 2B demonstrates an actual increase in binding of VWF to platelets. This causes the platelets and VWF subunits to be quickly removed from the plasma, which results in abnormal function;
- Type 2M, a rare type of VWD, causes a marked reduction in the binding of VWF to the platelets despite normal distribution of all VWF subunits;
- Type 2N demonstrates a marked decrease in binding of VWF to FVIII.
- VWD Type 3: The least common and most severe form of VWD, in which an individual inherits an altered gene from both parents. VWF may be almost completely absent in these patients, and they often have low FVIII and VWF activity levels.
- Pseudo (or platelet-type) VWD: Clinically similar to VWD Type 2B, pseudo VWD is caused by defects in the platelets rather than by defects in or deficiencies of VWF.
Prevalence of VWD in the US Population
The Centers for Disease Control and Prevention (CDC) collect data on patients with bleeding disorders as part of the Universal Data Collection (UDC) Project. This database provides the prevalence of different subtypes of VWD among patients treated at hemophilia treatment centers (HTCs) in the United States. This database (accessed April 04, 2010) currently includes 5505 patients with VWD, of whom 83.5% (4597) have Type 1, 10.8% (595) have Type 2, and 5.6% (313) have Type 3.
Causes of VWD
VWD is an inherited bleeding disorder caused by reduced levels (Types 1 and 3) or abnormalities in the functioning (Type 2) of VWF.3 VWD is transmitted on an autosomal (non-sex linked) chromosome, meaning that children of both genders are equally likely to inherit the gene (unlike in hemophilia). There are subtle differences in inheritance patterns depending on the type of VWD:
- VWD Type 1: If either parent has an altered gene that results in VWD Type 1, there is a 50% chance that each child of that parent will inherit the VWD gene. However, for reasons not yet understood, in some cases the VWD gene is present but “non-penetrant”, meaning that it does not result in clinically evident VWD in the individual. These individuals still have a 50% chance of passing the gene on to offspring who may (or may not) express VWD Type 1.
- VWD Type 2: As with Type 1, if either parent has an altered gene resulting in VWD Type 2, there is a 50% chance that the children of that parent will inherit the VWD gene. However, unlike Type 1, when the gene for Type 2 is present, it is always expressed. Therefore, all persons with the gene will have clinical evidence of VWD Type 2.
- VWD Type 3: The most severe form of VWD, Type 3 occurs when both parents have an altered gene resulting in some form of VWD and their child receives an altered gene from each parent. When both parents have an altered gene for VWD Type 1, there is:
- 25% chance that each child will have VWD Type 3;
- 50% chance that each child will inherit a gene for VWD Type 1;
- 25% chance that each child will not inherit an altered VWD gene.
To see pictures of inheritance patterns in individuals with VWD, visit the Genetics Home Reference, a service of the US National Library of Medicine at http://ghr.nlm.nih.gov/handbook/inheritance/riskassessment.
Signs & Symptoms of VWD
Bleeding symptoms in VWD tend to occur in the mucosal lining or skin. The most common symptoms in persons diagnosed with VWD include the following4:
- Nose-bleeding (epistaxis) (see IHTC’s informational brochure)
- Abnormal or easy bruising (ecchymoses or hematomas)
- Bleeding of the gums (gingivitis)
- Bleeding after surgery (postoperative)
- Gastrointestinal bleeding
- Urogenital tract bleeding
Patients may also see a hematologist due to abnormal bleeding after surgeries including, but not limited to:
- Tonsillectomy and adenoidectomy
- Dental extractions, such as wisdom teeth
- Urogenital surgical procedures
Women may have bleeding complications related to their menstrual periods and labor and delivery. Common symptoms in women may include:
- Menorrhagia – abnormal, excessive and/or prolonged menstrual bleeding; a critical clinical issue in females, affecting up to 95% of women with VWD.1,5
- Metrorrhagia – bleeding between periods
- Postpartum bleeding: Heavy bleeding and/or hemorrhage during after labor/delivery
VWD Type 3 may share the clinical symptoms and complications associated with moderate to severe FVIII deficiency. For instance, patients with Type 3 VWD may experience bleeding into the joints or joint spaces (hemarthrosis)3, because of an associated deficiency of FVIII. For more information on FVIII deficiency (hemophilia A), click here.
If you or a family member with a bleeding disorder needs to visit the emergency department (ED), be sure to contact the IHTC first so that the center can help you get the best possible emergency and follow-up care. Visit our webpage on Emergency Care to learn about what patients and their families should do, what they need to take to the ED, and what information they need to provide to the ED staff. Read the IHTC’s useful Emergency Care Tips and keep it handy
Diagnosis of VWD
Accurately diagnosing VWD Type 1 can be a challenge. Many bleeding symptoms associated with VWD, including menorrhagia, are common in unaffected populations, so it can be difficult to identify bleeding symptoms that are abnormal or excessive. Moreover, because VWD runs in families, symptoms such as easy bruising, bleeding gums, and menorrhagia often seem “normal” to family members and are overlooked as potential signs of a bleeding disorder. If you are being evaluated for VWD, you should inform your healthcare provider about your personal or family history of bleeding. In general, healthcare professionals need to consider the following information1,4:
- Your personal history of bleeding
- Your family history of bleeding
- Results of physical examination
- Results of laboratory testing
Confirming a diagnosis of VWD Type 1 may require testing more than once. VWF levels can change depending on various factors, such as physical or emotional stress, exercise, systemic inflammation, pregnancy, and use of birth control pills. These variables can increase VWF levels and cause a false-negative result. Diagnosing VWD Types 2 and 3 is more straightforward.1
The Medical and Scientific Advisory Council (MASAC) of the National Hemophilia Foundation (NHF) advises that VWD and other inherited bleeding disorders should be considered when evaluating all females who are seen by healthcare professionals for abnormal or excessive bleeding.6 Project Red Flag, the NHF’s public awareness campaign , estimates that more than 2.5 million women in the United States have an undiagnosed bleeding disorder.4 Moreover, particularly in women, there is a significant delay between the start of bleeding symptoms and diagnosis, with symptoms starting at around age 12 years and diagnosis occurring at about age 16 years.5
Treatment of VWD
Treatment and management of VWD depends on the subtype and severity, as well as the patient’s age and symptoms. Prevention of bleeding is a primary treatment aim. Specific treatment options can increase VWF levels. In addition, supportive therapies can prevent or control bleeding symptoms. The main treatment options include the following7,8:
- Desmopressin acetate (DDAVP; Stimate) nasal spray or injection
- Synthetic hormone that increases the body’s release of VWF;
- To be used in patients with Type 1 VWD and in hemophilia patients with mild factor FVIII deficiency (>5%);
- Nasal spray recommended only for patients >3 years old and weighing more than 20 kg.
- To use desmopressin, patients should undergo a DDAVP challenge test to see if they have a satisfactory response, because desmopressin is not effective in all patients;
- Click here to download the IHTC’s fluid restriction guidelines and other information on DDAVP/Stimate use.
- VWF-containing concentrates (eg, Humate-P)
- These concentrates are derived from donated human blood that has undergone viral inactivation.
- The concentrates are usually given intravenously (through the vein) to increase the level of VWF.
- To be used in:
- People with VWD type 2A, type 2B and type 3, in type 1 with severe bleeding;
- Patients who are unresponsive to or cannot use desmopressin (DDAVP);
- Patients undergoing major surgical procedures involving areas of fibrinolysis (clot breakdown and removal), such as the oral airway region or urogenital area.
- Aminocaproic acid
- Antifibrinolytic agent that may be used in patients with bleeding disorders;
- Prevents breakdown of the blood clot and helps maintain hemostasis (normal blood clotting);
- Used to treat mucous membrane bleeding;
- Commonly used as an additional treatment along with DDAVP/Stimate or VWF-containing concentrates.
- Oral contraceptives
- May be used in women whose primary symptom is menorrhagia or metrorrhagia.
- Additional Therapies and Precautions
- Use local topical blood-clotting agents such as fibrin glue or microfibrillar collagen, or tranexamic acid.
- Avoid medications that may increase bleeding, such as aspirin or other antiplatelet drugs
- Use precaution when receiving recommended immunizations – injections should be given in the thigh or other large muscle group(s) using the smallest size needle;
- No more than one immunization in one muscle group per visit;
- Apply ice and pressure after immunization for 3 to 5 minutes each.
- Get vaccinated against hepatitis A and B if you are not immune or have not been previously exposed;
- Be aware that individuals with bleeding disorders have an increased risk of exposure to blood and blood products;
- Start treatment as soon as possible after diagnosis;
- Maintain an ideal weight and an active lifestyle to increase muscle tone and preserve joint function.
Recombinant VWF (VWF product that is not made from human plasma) is available in clinical trials but is not available for routine clinical use. This means that patients with VWD who need to use a concentrate containing VWF must use plasma-derived concentrates. Intensive screening, testing and advanced purification processes have greatly reduced the risk of hepatitis A, B or C, and HIV with plasma-derived products.
Treatment Adherence in VWD Care
The effectiveness of treatment of VWD depends on two important variables: the physician recommending an appropriate treatment plan for the patient’s condition, and the patient following the recommendations provided. Treatment adherence is the extent to which a patient’s behavior coincides with medical or health advice. Individuals with type 3 VWD may share the clinical symptoms and complications associated with moderate to severe hemophilia. Because individuals with type 3 VWD often require infusion therapy at home, they must be actively involved in working with physicians to plan and manage their treatment regimen.
Poor adherence to a treatment plan may reduce treatment effectiveness and contribute to long-term disability and decreased quality of life in patients with type 3 VWD. Nonadherence to on-demand/episodic therapy may result in bleeding episodes of longer duration, recurrent bleeds in the same location, joint damage and subsequent disability. Nonadherence to prophylactic therapy may cause suboptimal prevention of bleeding events and lead to the poor outcomes. Because clotting factor and other medications for the treatment of type 3 VWD are expensive it is especially important for patients to adhere to treatment recommendations to prevent complications and reduce waste of valuable medical resources.
While most healthcare providers agree that treatment adherence is an important issue in health outcomes, historically there has not been an effective way to measure treatment adherence in individuals with bleeding disorders. Different studies of individuals with hemophilia have used infusion logs, clotting factor dispensations, joint health, and patient interviews to evaluate adherence. However, none of these studies resulted in a standardized method to measure adherence to hemophilia treatment. In response to the need for a standardized adherence measure, the IHTC developed and validated two scales to measure treatment adherence – the Validated Hemophilia Regimen Treatment Adherence Scales (VERITAS) for episodic treatment (VERITAS-PRN) and for prophylactic treatment (VERITAS-Pro).
VERITAS: IHTC’s Validated Treatment Adherence Scales
Each VERITAS scale includes 24 questions divided into six 4-question subscales. The subscales are designed to measure different aspects of treatment adherence, including the dosage and timing of infusions, the patient’s tendency to forget or skip infusions, and the frequency of communication between the patient and the HTC. Using the individual subscale scores as well as the total score allows care providers to evaluate multiple dimensions of adherence and to identify areas that should be addressed to improve adherence and optimize long-term health outcomes for the patient.
The validation process involved developing these questionnaires and testing them in patient groups to demonstrate that the scales measure what they purport to measure, i.e., that they measure actual treatment adherence and not another aspect of treatment. We demonstrated that the scales reliably measure treatment adherence and represent a valuable tool for use in patient care. The scales take less than ten minutes to complete and are a simple and highly informative addition to a patient’s clinic visit and care.
Both scales were published in Haemophilia, a leading peer-reviewed journal, in early 20109,10 and have been well received in the hemophilia community. To date, the IHTC team has presented the scales at the American Society of Hematology, World Federation of Hemophilia, the International Network for Pediatric Hemophilia, and the first Conference on Blood Disorders in Public Health. The VERITAS-Pro is currently undergoing translation into Spanish, Italian, and French, and has been introduced to multiple clinic settings and added to several pharmaceutical study protocols. It is our hope that the VERITAS scales will improve our understanding of the link between treatment adherence and health outcomes, and thus significantly influence our ability to help patients achieve the best long-term outcomes possible.
Please use the following links to read the VERITAS study abstracts in the journal Haemophilia.
For additional information about the tools, please contact the IHTC disease management team at 1 317 871 0011 (ext. 273).
Hemophilia Treatment Centers and Comprehensive Care
The federal Office of Maternal and Child Health and the Centers for Disease Control and Prevention (CDC) support a network of specialized healthcare centers dedicated to treating blood disorders.11 Currently, the network includes about 140 HTCs. The IHTC is Indiana’s only federally recognized HTC.
The purpose of HTCs is to prevent and reduce problems related to blood disorders by providing optimal and comprehensive care to persons with bleeding disorders, thrombosis, and thrombophilia (clotting disorders). The centers have multidisciplinary clinic teams, research initiatives, and outreach and education programs. The multidisciplinary team typically includes:
- adult and pediatric hematologists
- triage and clinic nurses
- social workers and other mental health professionals
- dental hygienists
- physical therapists
- research coordinators
The teams work closely with local healthcare providers to meet the specific needs of the affected persons to improve their quality of life. The care provided at HTCs has been shown to significantly improve prevention of complications for persons with hemophilia. Mortality rates are 40% lower in persons who use HTCs than in those who do not, despite the fact that the more severely affected patients are the ones who typically visit these centers.12 HTCs place a premium on preventive care to prevent complications that can reduce the patients’ quality of life.
The IHTC exceeds national staffing standards and offers an extensive spectrum of care and services through dedicated trained professionals. In addition to the core services provided at all HTCs (e.g., hematologists, clinical nurses, social workers, physiotherapists), the IHTC staff also includes a career counselor, risk reduction specialists, a registered dietitian, genetic counselor, dental hygienists, and clinical research professionals.
IHTC’s Disease Management Program: Optimizing Patient Care While Minimizing Costs
Since October 2004, the IHTC has administered a disease management program (DMP) for persons with bleeding disorders who are insured by Indiana’s high-risk insurance pool, the Indiana Comprehensive Health Insurance Association (ICHIA). Indiana code I.C. 27-8-10-3.5(e) mandates that ICHIA-insured individuals with chronic diseases participate in an ICHIA-approved DMP. Because of IHTC’s specialized focus on bleeding disorders and commitment to excellence in patient care, it was selected as the disease management entity for ICHIA-insured individuals with bleeding disorders.
The purpose of the DMP is to optimize patient care and health outcomes while containing or reducing costs of care. The program brings together expertise, experience, and advanced technology in a patient-focused, research-oriented approach. Included elements of the DMP are targeted toward the most accurate, effective, and efficient methods to diagnose and treat bleeding disorder complications. Through targeted interventions and enhanced quality assurance, this program is expected to result in improved patient care and cost stabilization/savings.
Patients enrolled in the program are required to do the following:
- Attend an annual comprehensive clinic at the IHTC or at an outreach location;
- Have prescriptions for clotting factor concentrate and other bleeding disorder medications signed by an IHTC physician;
- Obtain outpatient clotting factor and related products through one of the ICHIA DMP Public Health Service vendors, such as the IHTC Pharmacy Program;
- Engage in periodic telephone contact with IHTC/DMP nurses and staff regarding ongoing health issues, psychosocial concerns, and educational or occupational needs;
- Complete DMP questionnaires and assessments upon request;
- Use the ATHNadvoy web-based infusion reporting system or other approved infusion reporting system to log infusions.
Program enrollees also have the option to participate in the research component of the DMP, whereby program results may be presented to other HTCs and/or published in academic journals. Patient privacy is always an IHTC priority. Any data that are published or presented are de-identified and aggregated so that no individual patient can be linked to the information.
Evaluation of Progress
The following tools are used to evaluate program progress:
- Monthly meetings of the multidisciplinary team to review DMP patients’ health status, progress, and needs;
- Pharmacoeconomic analysis of claims data – i.e., annual insurance claims are reviewed from year to year, with a special focus on costs of care, costs of clotting factor, source of care (e.g., HTC, emergency department), and changes in costs and utilization from one year to the next;
- Annual reporting of specific cost and utilization outcomes:
- Average costs of clotting factor, medical, and hospital care;
- Average number of clotting factor units dispensed, emergency department visits, and inpatient hospital days;
- Regular patient assessments:
- Diagnosis-specific knowledge assessments – to assess a patient’s knowledge of his or her own condition, and to assess changes in knowledge over time;
- Quality of life survey – to assess a patient’s health-related quality of life, and to assess changes in quality of life over time;
- Treatment adherence scale – VERITAS-Pro or VERITAS-PRN for patients who use a home infusion regimen.
The DMP is currently in its sixth year of administration. Five years after implementation, all costs, as well as emergency department visits, have remained below pre-implementation levels. Inpatient hospital days also have remained below pre-implementation, although a few spikes in costs for medically necessary surgeries have occurred. Program patients have benefited from the focus on proactive, preventive care and personalized interventions. A major strength of the IHTC DMP is that it is administered by healthcare providers rather than a third-party disease management entity. This ensures that program staff has direct access to the multidisciplinary medical team, physicians, and pharmacy. This model strongly supports the implementation of provider-administered DMPs in managing costly chronic disease and addressing the rising healthcare costs in the United States.
The IHTC team published the initial results of its DMP in Haemophilia, a leading peer-reviewed, academic journal. To access the abstract of the published article, click here.
If you are a woman with VWD, it is important that you talk about your personal and family bleeding history, particularly a history of menorrhagia, with your primary care provider, gynecologist, surgeon, or dentist before any surgery or procedure.
An international group of experts in the care of women with bleeding disorders recently published recommendations on how to specifically identify and manage bleeding disorders in women. To download a free copy of the recommendations to give to your healthcare providers, click here.
Women with VWD who become pregnant or plan to have a child should receive follow-up care from a hematologist and obstetrician who are skilled in the management of VWD. The obstetrician should work with the hematologist to develop a plan to prevent bleeding and to manage bleeding if it does occur. Pregnancies in women with VWD are often considered to be high risk; and delivery should occur at a facility with the capability to manage potential bleeding complications.
Good dental hygiene is important for all individuals, including those with bleeding disorders. However, individuals with bleeding disorders need to take some special precautions in preparing for dental procedures as well as in providing essential information to the dental care provider to ensure the best outcome after the procedure and in long-term dental health. Visit IHTC’s webpage on dental care to learn more about the special considerations for dental care in individuals with bleeding disorders.
For more information about VWD, visit the National Hemophilia Foundation’s website.
What Can the IHTC Do for You?
- As Indiana’s only federally recognized HTC, the IHTC is committed to working with other healthcare providers throughout the state to serve Indiana’s bleeding disorders population. We are available to answer any questions you or your healthcare provider might have about VWD in general and to consult about cases of suspected VWD or other bleeding disorders.
- IHTC will provide surgery plans for patients who need a surgical procedure. We gladly take referrals to our center and, based on the benefits of receiving care at an HTC,12 we encourage providers to involve the IHTC in the overall care of persons with VWD and their families.
- The IHTC exceeds national staffing standards and offers an extensive spectrum of care and services through dedicated trained professionals. In addition to the core services provided at all HTCs (e.g., hematologists, clinical nurses, social workers, physiotherapists), the IHTC staff also includes a career counselor, a risk reduction specialist, a registered dietitian, geneticist, dental hygienists, and clinical research professionals.
- Our Public Health Service 340B IHTC Pharmacy Program benefits payors and patients by reducing the cost of treatment, coordinating care, communicating with patients and their families to manage medication issues, and helping patients enroll in patient assistance programs so that patients have access to therapies during a lapse in insurance coverage.
- Genetic counseling is available through the IHTC for individuals and families with VWD.
- Our social workers help individuals with bleeding disorders and their families handle insurance issues.
- Dental care: IHTC’s dental hygienists will work with you and your dentist to make sure all the necessary precautions are taken in preparing for dental procedures and for long-term dental care. Visit IHTC’s webpage on dental care to learn more about the special considerations for dental care in persons with bleeding disorders.
- Outreach comprehensive clinic: As Indiana’s only federally recognized HTC, the IHTC is dedicated to serving persons with bleeding disorders throughout the state. In addition to seeing patients at our clinic, centrally located in Indianapolis, IHTC’s multidisciplinary medical team travels to several Indiana communities each year to conduct comprehensive clinics and follow-up care for patients living in these areas. To see the locations and dates of IHTC’s outreach comprehensive clinics in 2010, click here.
- IHTC partners with Hemophilia of Indiana Inc. (HII) to host Camp Brave Eagle, Indiana’s summer camp for children with bleeding disorders. The week-long camp is open to all Indiana children with bleeding disorders, as well as their siblings, ages 7–15 years. For more information on this camp, please click here (Camp Brave Eagle website). For photos of Camp Brave Eagle 2008, see IHTC’s Fall 2008 newsletter in our Reading Room.
- The Doug Thompson Teen Leadership Program provides teen members of the bleeding disorder community an opportunity to develop and refine life and leadership skills while participating in an adventure camp experience. Teen camp teaches teenagers how to mentally and physically prepare for nearly anything, while affirming the choice to not participate in activities that may put them at risk. For photos of the Thompson Outpost Teen Camp, see IHTC’s Fall 2008 newsletter in our Reading Room.
- Watch our IHTC News section on this website for further information on registration dates for Camp Brave Eagle and the Thompson Outpost Teen Camp!
- Do you have additional questions about VWD? Please see IHTC’s VWD FAQs.
Project Red Flag, National Hemophilia Foundation’s public awareness campaign for women with bleeding disorders.
- National Heart Lung and Blood Institute. The Diagnosis, Evaluation and Management of von Willebrand Disease. 2006. (Available at http://www.nhlbi.nih.gov/guidelines/vwd/3_diagnosisandevaluation.htm.). Accessed April 15, 2010.
- Lillicrap D. Von Willebrand disease–Phenotype versus genotype: Deficiency versus disease. Thrombosis Research 2007;120:S11-S6.
- Sadler J. von Willebrand Factor. The Journal of Biological Chemistry 1991;266:22777-80.
- National Hemophilia Foundation. Project Red Flag: Real Talk About Women’s Bleeding Disorders. 2009. (Available at http://www.hemophilia.org/projectredflag/index.htm.). Accessed April 15, 2010.
- Ragni M, Bontempo F, Hassett A. von Willebrand disease and bleeding in women. Haemophilia 1999;5:313-317.
- National Hemophilia Foundation. Medical and Scientific Advisory Council (MASAC). MASAC Recommendation #185: Regarding Women with Inherited Bleeding Disorders. Available at: http://www.hemophilia.org/NHFWeb/MainPgs/MainNHF.aspx?menuid=57&contentid=1192.). Accessed April 15, 2010.
- National Hemophilia Foundation. MASAC Recommendation #186: Regarding the Treatment of Von Willebrand Disease. 2008. (Available at http://www.hemophilia.org/NHFWeb/MainPgs/MainNHF.aspx?menuid=57&contentid=689.). Accessed April 15, 2010.
- Berntorp E, Abshire T. The von Willebrand Disease Prophylaxis Network (vWD PN): Exploring a treatment concept. Thrombosis Research 2006;118:S19-S22.
- Duncan NA, Kronenberger WG, Roberson CP, Shapiro AD. VERITAS-PRN: a new measure of adherence to episodic treatment regimens in haemophilia. Haemophilia. 2010;16:47-53.
- Duncan NA, Kronenberger WG, Roberson CP, Shapiro AD. VERITAS-Pro: a new measure of adherence to prophylactic regimens in haemophilia. Haemophilia. 2010;16:247-255.
- Centers for Disease Control and Prevention. Blood Disorders: Specialized Health Care. 2009. (Available at http://www.cdc.gov/ncbddd/blooddisorders/treatment.html.). Accessed April 15, 2010.
- Soucie J, Nuss R, Evatt B, Abdelhak A, Cowan L, Hill H, et al. Mortality among males with hemophilia: relations with source of medical care. Blood 2000;96:437-42.