at San Francisco, California and other locations
study started
estimated completion



This is a real-world study of the safety of the treatments used for people with hemophilia. The study will follow people with hemophilia A or B from across the country for about 4 years as they receive treatment. The hemophilia treatment center (HTC) physician and participant will decide on the FDA-approved treatment to be used which may include non-factor products, bypassing agents, or clotting factor replacement products. The goal of this research is to study the use of hemophilia treatment products and their outcomes.

Official Title

A Natural History Cohort Study of the Safety, Effectiveness, and Practice of Treatment for People With Hemophilia


This non-interventional, minimal risk cohort study will enroll and follow patients with hemophilia A or B as they receive hemophilia treatment for 4 years. This is a pragmatic study of real-world practices across a wide range of patients which will be ongoing as new treatment products receive FDA approval and will be advantageous to the entire hemophilia community. The total study duration is planned for 6 years. The patients are seen at baseline, annually, and at study exit. Patients will also receive routine quarterly follow-up phone calls from HTC staff to review medical history, bleed events, and product treatment history. Other visits for unplanned events or for the change of treatment product will be scheduled as necessary. All required study visits will be planned to coincide with routine clinical care whenever possible. Co-enrollment in the ATHNdataset by patients is required to participate in the study. Please note - the treatment regimen will be at the discretion of the patients' hemophilia caregivers. No treatment products are being provided by the study nor will the participants be paid. However, inhibitor titer testing will be provided at no cost to patients by the Center for Disease Control and Prevention (CDC). The primary objective is to determine the safety of non-factor products, bypassing agents or clotting factor replacement products when used for people with hemophilia with or without inhibitors. Safety will be measured by those events listed in the European Haemophilia Safety Surveillance (EUHASS). Data collected will include eligibility, demographics, medical history, hemophilia history (genotype and family history), inhibitor history and immune tolerance induction (ITI) treatment regimen (if applicable), co-morbidities at baseline (i.e., HIV, Hepatitis C), detailed treatment product(s) usage, bleeding events, surgical procedures, and EUHASS adverse events and other adverse events of special interest. Data collection will also include patient-reported outcome questionnaires regarding health-related quality of life, treatment use and patient perceptions of treatment products. Sub-studies A number of sub-studies are planned with pharmaceutical sponsors to collect information from patients about their specific product use. Participation in these sub-studies (Product Specific Modules) is optional and sub-study visits will be planned to coincide with HTC visits. The modules will collect information from patients about their perception and use of treatment products, physical activity levels and other general health questions. This data will be collected via questionnaire. Data Collection System All data collected will be entered into electronic case report forms (eCRFs) within the secure ATHN System by HTC site personnel. All participating study sites will have in place a current, executed Data Use and Business Associate Agreement (DUBAA) with ATHN.


Hemophilia A With Inhibitor Haemophilia A Without Inhibitor Hemophilia B With Inhibitor Haemophilia B Without Inhibitor Hemophilia Non-Factor Products Bypassing Agents Clotting Factor Replacement Products Hemophilia A Hemophilia B


You can join if…

  1. Congenital hemophilia A or B of any severity with or without inhibitors receiving a current therapy, a non-factor product, or for whom use of a non-factor product is a possibility;
  2. Able to give informed consent (by patient or parent/authorized guardian); and
  3. Co-enrollment in the ATHNdataset.

You CAN'T join if...

  1. Presence of any known bleeding disorder other than congenital hemophilia A or B;
  2. Presence of concurrent hemophilia and a second hemostatic defect (low Von Willebrand Factor (VWF) without Von Willebrand disease (VWD) diagnosis is not excluded); and
  3. Unable or unwilling to comply with the study protocol.


  • UCSF Pediatric Hemophilia Treatment Center at Mission Bay
    San Francisco California 94158 United States
  • UCD Hemostasis and Thrombosis Center
    Sacramento California 95817 United States


in progress, not accepting new patients
Start Date
Completion Date
American Thrombosis and Hemostasis Network
Centers for Disease Control accessed
Study Type
Observational [Patient Registry]
At least 395 people participating
Last Updated