Preferences of Patients with Congenital Thrombotic Thrombocytopenic Purpura and Other Chronic Conditions for in-Home Prophylactic Infusions
Authors: Batchelder Laurie , Sun Shawn X. , Casamayor Montserrat , Rodríguez Ana María 
Published: December 2023

Background
Congenital thrombotic thrombocytopenic purpura (cTTP) is an ultra-rare, life-threatening, thrombotic microangiopathy caused by an inherited deficiency of the von Willebrand factor (VWF)-cleaving enzyme ADAMTS13. Current treatment approaches include replacement therapy with intravenous (IV) infusions of either fresh frozen plasma, solvent/detergent-treated plasma, or factor VIII/VWF concentrates administered in a hospital/clinical setting. There is recent interest in novel treatments for cTTP and other chronic conditions where patients may be able to receive treatment at home with limited risk and a manageable safety profile compared to outpatient treatment. Understanding patient preferences regarding treatment at home vs an outpatient setting could help to inform approaches to patient care for both cTTP and other chronic conditions.
Aims
The primary objective was to assess stated preferences of patients with either cTTP or another chronic condition requiring treatment with regular IV infusions (listed in Table 1) toward prophylactic infusions administered at home vs in an outpatient setting. Secondary objectives were to estimate the utility and disutility of 7 attributes (listed in Table 2) associated with patient preferences and to assess whether clinical, sociodemographic, or other factors influence patient preferences.
Methods
This cross-sectional cohort study utilized an online discrete choice experiment survey, in which patients were presented with pairwise choice sets consisting of 7 attributes and their associated levels (listed in Table 2). In the survey, each patient was asked to choose their preferred alternative in a choice set (repeated 16 times) using different combinations of varying attribute levels for all 7 attributes, using an orthogonal experimental design. The survey also included a time trade-off exercise to enable the attribute levels to be adjusted for quality adjusted life years. The survey was conducted in France, Germany, Spain, the UK, and the US. Patients ≥18 years old with either cTTP or another chronic condition (listed in Table 1) who were receiving prophylactic IV infusions for ≥3 months, in either an outpatient setting or a hybrid outpatient and at-home setting, were eligible for inclusion. Treatment frequency ranged from once a week to once every 3 weeks. Data were analyzed using multinomial logit regression models.
Results
In total, 307 complete patient responses (France, n=18; Germany, n=95; Spain, n=96; UK, n=7; US, n=91) were included in the analyses. Median (range) age was 44.0 (20.0-78.0) years and 25 patients (8.1%) had cTTP ( Table 1). Overall, 137 patients (44.6%) reported an overall preference for receiving infusions at home, 85 patients (27.7%) reported a preference for receiving treatment in a hospital/clinic, and 85 patients (27.7%) reported a preference for receiving treatment via a hybrid outpatient and at-home setting. The majority of patients would prefer either a doctor or a nurse to administer their treatment at home (n=125, 40.7%). Patients placed significantly greater value on certain treatment-setting attributes ( Table 2); being comfortable with the treatment environment was considered the most important attribute. For the ‘convenience and impact on daily life’ attribute, selection of ‘flexibility in scheduling infusions’ was influenced by age (estimate: 0.019, 95% CI: 0.007; 0.032), and whether the patient had been diagnosed &gt;5 years ago vs &lt;1 year ago (estimate: 0.744, 95% CI: 0.255; 1.269). A high proportion of patients (60.9%) were willing to trade 12 months of their lives to receive treatment at home. Also, 59.0% and 56.4% of patients, respectively, were willing to trade 12 months to ensure that complications did not necessitate treatment in a hospital setting and that travelling to a hospital/clinic was not required to receive prophylaxis.
Conclusions
The majority of patients with cTTP or another chronic condition requiring treatment with regular IV infusions stated that they would prefer to receive treatment at home with support from healthcare providers. A high proportion of patients were also willing to trade 12 months of their lives to receive treatment at home; a limitation of the time trade-off exercise was that the maximum time that could be traded was 12 months. These findings provide insights into the importance of the treatment setting preferences of patients receiving prophylactic infusions.