Prospective Psychometric Evaluation Study of a Patient-reported Outcomes (PRO) Instrument for Congenital Thrombotic Thrombocytopenic Purpura (cTTP, Upshaw-Schulman Syndrome [USS], Hereditary Thrombotic Thrombocytopenic Purpura [hTTP]

Prospective Psychometric Evaluation Study of a Patient-reported Outcomes (PRO) Instrument for Congenital Thrombotic Thrombocytopenic Purpura (cTTP, Upshaw-Schulman Syndrome [USS], Hereditary Thrombotic Thrombocytopenic Purpura [hTTP]

The purpose of this study is to assess the psychometric properties of a recently developed congenital thrombotic thrombocytopenic purpura (cTTP)-specific patient-reported outcomes (PRO) instrument.

Inclusion criteria:

1. The participant is an adolescent aged 12 to 17 years or an adult aged ≥18 years;
2. The participant has been diagnosed with congenital thrombotic thrombocytopenic purpura (cTTP) and is currently receiving prophylactic or on-demand treatment with fresh frozen plasma (FFP), or solvent detergent (S/D) plasma, or Von Willebrand Factor/Factor VIII (VWF/FVIII) concentrates;
3. In the instance that the participant is identified and recruited remotely (Direct-to-Patient (DtP) recruitment), access to the internet and possession of an internet-connecting device is required;
4. The participant has provided informed consent, and in the instance that the participant is an adolescent, a legal guardian has provided informed consent and the adolescent has provided assent.

Exclusion criteria:

1. The participant cannot read nor write;
2. The participant is non-English speaking;
3. The participant is currently participating in a clinical trial.