{'fraction_non_alphanumeric': 0.04351116155883466, 'fraction_numerical': 0.02724177071509648, 'mean_word_length': 5.133410672853828, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 1, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Perceptions about the efficacy of extended half‐life (EHL) factor products in persons with haemophilia (PWH): A national survey of haemophilia providers from haemophilia treatment centres (HTCs) in the United States

Dear Editor, Extended half-life factor products (EHLs) have been shown to reduce treatment burden in persons with haemophilia (PWH).1,2 The half-life of factor VIII EHLs (FVIII-EHLs) is 1.4 to 1.6-fold longer than standard half-life concentrates (SHLs),1 reducing the infusion frequency to twice a week from 3 to 4 times per week in persons with haemophilia A (PWHA). Factor IX EHLs (FIX-EHLs) have a 3 to 6fold half-life prolongation, further reducing the infusion burden to once every 7 to 14 days in persons with haemophilia B (PWHB).1 Consequently, EHLs improve therapy adherence3–5 and quality of life (QOL) in PWH6 leading to many patients being switched from SHLs to EHLs.7,8 Interestingly, few centres have reported suboptimal efficacy of FIXEHLs in preventing and controlling acute bleeding diatheses and surgical bleeding.9 This study from four haemophilia treatment centres (HTCs) in the United States showed that a subset of PWHB (18%, n = 13/71) experienced break-through bleeding with prophylaxis and suboptimal bleed control with FIX-EHLs.9 Since there is limited postmarketing data, it is unclear if other providers had similar experiences with FIX-EHLs and if there were unshared concerns about FVIII-EHLs. We sought to gain more insight about the real-life experience of clinicians with EHLs through an online survey of haemophilia treaters from federally fundedHTCs across theUnited States. Our goal was to examine the clinician perceptions about the efficacy of EHLs in PWH, specifically for managing acute bleeding diatheses and surgeries. The survey instrument was designed using Qualtrics® platform (Qualtrics, Provo, UT). The surveywas sent electronically fromNovember 2019 through February 2020 to ‘providers treating PWH at HTCs in the United States’. Survey participation was voluntary, anonymous and an attempt to respond implied consent. The survey instrument had 33 multiple choice questions divided into six domains: (i) Provider demographics, (ii) Epidemiology of EHL use at participants’ HTCs, (iii) Laboratorymonitoring of EHLs, (iv) Clinical scenarioswith acute bleeding and surgery in PWH, (v) Reasons for discontinuing EHLs and (vi) General concerns with EHLs for managing acute bleeding diatheses. Analyses were limited to participants who completed the survey, and descriptive statistics was reported in the results. Seventy providers from 149HTCs (response rate, 47%; 95%CI 39% to 55%) completed the survey. Majority, 68% (n = 48/70) were paediatric haematologists, 61% (n = 43/70) had > 10 years of practice experience and 21% (n = 15/70) belonged to the Great Plains States. EHLswereused for standardprophylaxis by30% (n=70/235), episodic prophylaxis for sports and surgery by 16% (n = 36/235), and ondemand therapy by 15% (n= 34/235). Forty-seven percent (n= 33/70) used EHLs in previously untreated patients (PUPs). Sixty-five percent (n= 46/70) used EHLs formanaging acute bleeds in personswithmoderate haemophilia, and23% (n=16/70) usedEHLs in personswithmild haemophilia. Fifty eight percent (n = 41/70) were willing to switch all PWHB to EHLs, whereas only 20% (n = 14/70) were willing to switch all PWHA to EHLs. Majority, ∼94% (n = 66/70) for PWHA and ∼84% (n = 59/70) for PWHB preferred to use the same EHL concentrate for managing break-through bleeding in PWH receiving EHL prophylaxis. These data indicated that clinicians were comfortable using EHLs for the same indications as that of SHLs including standard prophylaxis, on-demand therapy, episodic prophylaxis and break-through bleeding. Our finding that clinicians were using EHLs in persons with non-severe haemophilia is novel though it makes intuitive sense. Approximately 20% (n = 43/235) used EHLs based on patient preference, suggesting that patient families were involved in decision-making. The use of EHLs in PUPs by almost half of the participants was surprising as safety and efficacy data of EHLs for PUPs are awaited. This decision may be driven by challenges with venepuncture and emerging data about low immunogenicity of EHLs.10 It was not surprising that more providers were willing to switch PWHB to EHLs than PWHA. Clearly substantial reduction in infusion burden with FIX-EHLs is critical for patients’ QOL.8 Moreover, the availability of non-factor therapies like emicizumabmay be playing a role for PWHA.11 Through the subsequent section, we sought to understand clinician preferences with laboratory monitoring of EHLs. Although ∼60% (n = 43/70) of respondents performed pharmacokinetic (PK) analyses to determine the regimen with EHLs, providers varied in their preference of PK time-points. This variability likely stems from the lack of uniform guidelines to monitor EHLs. Some providers endorsed that they were more comfortable with monitoring SHLs due to their longer acquaintance with these concentrates prior to availability of EHLs. To understand comfort level of using EHLs for acute haemarthrosis, clinicians were given two clinical scenarios of PWH on prophylaxis who presented with hip bleeding and elbow bleeding. To achieve