Race and ethnicity and the success of immune tolerance induction among people with severe haemophilia A in the United States.

INTRODUCTION: Immune tolerance induction (ITI) is the only treatment to eradicate inhibitors in people with severe haemophilia A with inhibitors. Since the risk of inhibitor development is greater among Black and Hispanic persons, it has been hypothesized that race and ethnicity may influence ITI success. Limited studies have evaluated this hypothesis. AIM: To examine the success of ITI according to race and ethnicity. METHODS: Participants who entered the Community Counts (CC) Registry between 2013 and 2017, were aged ≥3 years at study entry, and received ITI were included (n = 559). The proportion of participants with successful ITI was examined with adjusted prevalence ratios (aPRs) and corresponding 95% confidence intervals (95% CIs). RESULTS: Among 559 participants, 56.9%, 19.1%, 18.1% and 4.3% were Non-Hispanic (NH) White, NH Black, Hispanic and Asian, respectively, and 1.7% were coded as other or missing. Approximately 80% of Hispanic, NH Black and NH White participants had good/very good prognosis, defined as having a pre-ITI peak inhibitor of < 200 Bethesda Units per millilitre. Nearly 60% of participants (59.7%) achieved successful ITI, 20.7% and 19.5% experienced partially successful or failed ITI, respectively. Successful ITI was non-significantly lower in NH Black (54.2%; aPR = 0.95, 95% CI 0.62-1.44) and Hispanic (55.4%; aPR = 0.89, 95% CI 0.71-1.13) relative to NH White participants (62.6%). CONCLUSION: In this study, 60% of participants in the CC Registry had successful ITI, consistent with previous studies. The proportion with successful ITI was generally comparable across racial and ethnic groups with similar prognosis. These findings do not support the hypothesis that ITI response varies according to race or ethnicity.

Race and ethnicity reporting and representation in hemophilia clinical trials.

ABSTRACT: Racial and ethnic representativeness in clinical trials is crucial to mitigate disparities in outcomes; however, diversity among hemophilia trials is unknown. The aim of this study is to examine the reporting and representation of race and ethnicity in trials of people with hemophilia (PwH). In this cross-sectional study, the ClinicalTrials.gov database was queried in April 2023 for interventional clinical trials involving PwH between 2007 and 2022. The distribution of participants (observed) was compared with expected proportions based on US Hemophilia Treatment Center (HTC) and country-specific census data with observed-to-expected ratios (OERs). Of 129 trials included, 94.6% were industry sponsored, with a mean of 62 participants and mean age of 26.8 years. Overall, 52.0% (n = 66) of trials reported data on race and ethnicity, increasing from 13.9% in 2007-2012 to 22.5% in 2013-2016 to 100% in 2017-2022 (P = .001). Among these 66 trials, 65.8%, 22.8%, 5.1%, 3.9% of participants were White, Asian, Hispanic, and Black, respectively. OERs were 10% to 20% lower for White participants vs US HTC, and US, UK, and Canadian census populations and ∼75% lower for Black or Hispanic participants when compared with US HTC and US census population. OERs for Asian participants were 1.6 to 3 times higher than Canada, US, and UK census populations. The reporting of race and ethnicity in hemophilia trials has drastically improved; however, Black and Hispanic PwH remain especially underrepresented. To address these disparities, stakeholders across the clinical trial enterprise need to implement strategies to ensure equitable participation.

Long-term safety and efficacy results from the phase 3b, open-label, multicentre Continuation study of rurioctocog alfa pegol for prophylaxis in previously treated patients with severe haemophilia A.

INTRODUCTION: Previous studies reported the efficacy and safety profile of extended half-life PEGylated recombinant factor VIII (FVIII) rurioctocog alfa pegol (TAK-660, SHP660, BAX 855) in preventing bleeding in haemophilia A patients. AIM: This study evaluated long-term safety and efficacy of rurioctocog alfa pegol for prophylaxis and treatment of bleeding in previously treated children and adults. METHODS: In this phase 3b, prospective, open-label, multicentre study (NCT01945593), eligible patients ≤ 75 years with severe haemophilia A (FVIII < 1%) received prophylactic rurioctocog alfa pegol in a fixed dose (FD, twice-weekly or less frequent) or pharmacokinetic (PK)-tailored dose regimen. Co-primary endpoints were incidence of confirmed FVIII inhibitory antibody development and spontaneous annualized bleed rate (ABR), analysed using a generalised linear model. Secondary endpoints included overall haemostatic efficacy, occurrence of adverse events and health-related quality of life (HRQoL). RESULTS: Overall, 216 patients were included; mean (SD) age at enrolment was 22.8 (15.7) years. No patients developed confirmed FVIII inhibitors. The point estimate (95% CI) of mean spontaneous ABR was 1.20 (0.92-1.56) among 186 patients receiving twice-weekly FD prophylaxis and 0.96 (0.54-1.71) among 25 patients receiving PK-tailored prophylaxis. Overall haemostatic efficacy was rated good or excellent in 88.6% of all bleeds. No new safety signals were observed. Patients reported improvements in HRQoL measures of pain, and physical and mental well-being. CONCLUSION: These results highlight the long-term safety and efficacy of rurioctocog alfa pegol prophylaxis in previously treated children and adults with severe haemophilia A, with a safety profile similar to previous studies and continuing ABR reduction.

Real-world use of emicizumab in patients with haemophilia A: Bleeding outcomes and surgical procedures.

INTRODUCTION: Emicizumab is a recombinant humanized bispecific antibody that bridges factor IXa and factor X to mimic the cofactor function of factor VIII. It is approved to prevent bleeding in patients with haemophilia A (HA). Outside of clinical trials, there is limited data on outcomes of patients treated with emicizumab, particularly in children without inhibitors. AIM: To report our experience treating patients with emicizumab, including (a) bleeding rates pre and postemicizumab, (b) peri-procedural management and outcomes and (c) serious drug-related adverse events. METHODS: Multicentre observational study in patients with HA who started emicizumab prior to 15 May 2019. Data collection continued until 15 October 2019 and included demographics, disease history, bleeding events, invasive procedures, thrombotic events and death. Annualized bleeding rates (ABR) prior to emicizumab were compared to postemicizumab. RESULTS: Ninety-three patients (including three females) met inclusion criteria, 19 with an active inhibitor. Median age was 8.6 years; patients <12 years without inhibitors (n = 49) accounted for the majority. ABR dropped from 4.4 (inhibitors) and 1.6 (non-inhibitors) to 0.4 (both groups) on emicizumab, P = .0012 and .0025, respectively. There were 28 minor (21 port removals) and two major procedures. Three patients received 1-2 doses of unplanned factor postoperatively to treat minor bleeding events. No patient discontinued therapy, and there were no thrombotic events or deaths. DISCUSSION: Our favourable clinical experience with emicizumab is similar to that reported in the clinical trials. Notably, this is the largest cohort of patients <12 years without inhibitors treated with emicizumab.

Identification of the Intron 22 and Intron 1 Inversions of the Factor VIII Gene in Iraqi Kurdish Patients With Hemophilia A.

Hemophilia A (HA) is a severe coagulation disorder affecting 1 in 5000 to 10 000 male births. In severe cases, the most deleterious large DNA rearrangements are inversions of intron 22 (Inv22) and intron 1 (Inv1) of the factor VIII (FVIII) gene. These account for 40% to 50% and 1% to 5% of all causative mutations, respectively. Nevertheless, no genetic analysis to identify the actual causative mutation of FVIII, particularly Inv22 and Inv1, among Iraqi Kurdish hemophiliacs has been performed. In this study, we aimed to genotype Inv22 and Inv1 of the FVIII gene in our patients with HA and reveal the genotype/phenotype correlation with the inversion mutations and their role as a risk factor for the development of inhibitors. Analyses of the Inv22 and Inv1 mutations in 80 Iraqi Kurdish patients with HA (60 severe, 18 moderate, and 2 mild) were performed using the inverse shifting-polymerase chain reaction (IS-PCR) method. In severe cases, 46.7% (28/60) had Inv22 and 3.3% (2/60) had Inv1. The genotype/phenotype relation of Inv22 and Inv1 illustrated a statistically significant association (P = .012) between disease severity and inversion mutations. Slightly more patients with Inv22 (39%) developed inhibitors than those without Inv22 (28%; odds ratio = 1.65, 95% confidence interval = 0.56-4.87, P = .361). Inv22 is a major cause of severe HA in Iraqi Kurdish patients, and IS-PCR is a rapid, robust, and effective method that can be applied for carrier detection and prenatal diagnosis of HA in developing countries.

Translation, validation and reliability of the functional capacity questionnaire Haemophilia Activities List for haemophilia patients in Brazil.

INTRODUCTION: To date, none of the available assessment instruments to evaluate functional abilities for individuals with haemophilia has been translated and validated in Brazil. AIM: To translate, and test the construct validity, internal consistency and the reliability of the Haemophilia Activities List (HAL) for the Brazilian population with severe and moderate haemophilia (type A or B) and to investigate differences in the self-perception of functional abilities in patients adults with haemophilia classified according to the presence of joint bleeding and the performance of orthopaedic surgeries. METHODS: The translation and transcultural adaptation following the steps: (a) translation; (b) synthesis (consensual version); (c) back-translation; (d) review by the committee of experts; (e) pretest in the target population; and (f) final version of the instrument. Correlations between HAL scores and the scores of the Health Assessment Questionnaire (HAQ) and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) were determined for construct validation. Reliability was tested using the test and retest method, and internal consistency was calculated by Cronbach's α. RESULTS: The HAL-BR was applied to 52 individuals with haemophilia (34.51 ± 12.87 years). The process of translation and cross-cultural adaptation produced similar versions between the translations A moderate correlation was observed between HAL and the HAQ (r = -0.55) and WOMAC scores (r = -0.58). The reliability was ICC = 0.972, CI (0.917-0.997) ICC = 0.876, CI (0.631-0.978) for inter- and intra-examiners. No difference was found in the total HAL score between the groups with and without bleeding. The group subjected to surgery compared to the group of not subjected to surgery presented in the HAL domains worse function in 'lying down/sitting/kneeling/standing', 'self-care' and 'complex lower extremities activities' as well as in total HAL score. CONCLUSION: The Brazilian version of the HAL was proven to be a valid and reliable evaluation tool for adults with haemophilia in Brazil.

Exploring regional variations in the cross-cultural, international implementation of the Patient Reported Outcomes Burdens and Experience (PROBE) study.

BACKGROUND: The Patient Reported Outcomes Burdens and Experience (PROBE) study has developed and validated the PROBE questionnaire for assessing patient-reported outcomes in people with haemophilia and participants without bleeding disorders. OBJECTIVE: To explore the regional variations in the international implementation of the PROBE questionnaire. METHODS: Data were collected from participants in four regions (Western Pacific, South America, North America and Europe). Participants were able to choose English or translated versions of the PROBE questionnaire into their first language. We used analysis of variance methods and multivariable regression to determine the relative contribution of the variance explained by region controlling for haemophilia diagnosis, age group and levels of educations. We also explored interactions between region and the other components. RESULTS: We used 862 questionnaires from 14 countries. Mean age of participants was 40.03 years (standard deviation 13.89), and 73.67% were male. After adjusting, region contributed 0.44%-7.98% of the variance component in subitem scores and 0.26% in the PROBE score. Years of education contributed 0.34% in the PROBE score. Age and haemophilia diagnosis contributed 3.42% and 22.42% of the PROBE score. CONCLUSIONS: The results demonstrate that the PROBE questionnaire is valid to implement for assessing health status among patients with haemophilia and participants without bleeding disorders across regions.

Racial Differences in Chronic Pain and Quality of Life among Adolescents and Young Adults with Moderate or Severe Hemophilia.

BACKGROUND AND OBJECTIVE: We explored racial differences in adherence to recommended clotting factor treatment regimens, chronic pain, and quality of life (QoL) among adolescents and young adults (AYAs) diagnosed with moderate or severe hemophilia. METHODS: A convenience sample of hemophilia patients aged 13-25 years completed an online cross-sectional survey in 2012. Chronic pain was measured using the revised Faces Pain Scale (FPS-R) and dichotomized as high (FPS-R ≥ 4) or low (FPS-R < 4). QoL was measured with the SF-36. RESULTS: Of 80 AYA participants (79 male), most had severe disease (91 %) and hemophilia A (91 %). Most were white (76 %) and non-Hispanic (88 %). At the univariate level, compared to whites, non-whites were more likely to have produced an inhibitor against clotting factor treatment (74 vs 38 %, p < .01), less likely to have commercial health insurance (16 vs 63 %, p < .001), more likely to report high levels of chronic pain (FPS-R ≥ 4) (63 vs 26 %, p < .01), and had lower SF-36 physical composite summary (PCS) scores. Adjusted logistic and quantile regression modeling, respectively, revealed that non-whites were 5.31 (95 % CI 1.62, 17.4; p < .01) times more likely to report high chronic pain and had median PCS scores that were 26.0 (95 % CI 11.0, 40.9; p < .01) points lower than whites. CONCLUSIONS: Targeted efforts to prevent and manage chronic pain among non-white AYAs with moderate or severe hemophilia are necessary. After accounting for demographic and clinical differences, there were no racial differences in adherence to recommended clotting factor treatment regimens; however, non-whites were more than five times more likely to report high levels of chronic pain, which predicted worse overall physical QoL, bodily pain, physical and social functioning, and greater role limitations due to physical health.

Complexity and diversity of F8 genetic variations in the 1000 genomes.

BACKGROUND: Hemophilia A (HA) is an X-linked bleeding disorder caused by deleterious mutations in the coagulation factor VIII gene (F8). To date, F8 mutations have been documented predominantly in European subjects and in American subjects of European descent. Information on F8 variants in individuals of more diverse ethnic backgrounds is limited. OBJECTIVES: To discover novel and rare F8 variants, and to characterize F8 variants in diverse population backgrounds. PATIENTS/METHODS: We analyzed 2535 subjects, including 26 different ethnicities, whose data were available from the 1000 Genomes Project (1000G) phase 3 dataset, for F8 variants and their potential functional impact. RESULTS: We identified 3030 single nucleotide variants, 31 short deletions and insertions (Indels) and a large, 497 kb, deletion. Among all variants, 86.4% were rare variants and 55.6% were novel. Eighteen variants previously associated with HA were found in our study. Most of these 'HA variants' were ethnic-specific with low allele frequency; however, one variant (p.M2257V) was present in 27% of African subjects. The p.E132D, p.T281A, p.A303V and p.D422H 'HA variants' were identified only in males. Twelve novel missense variants were predicted to be deleterious. The large deletion was discovered in eight female subjects without affecting F8 transcription and the transcription of genes on the X chromosome. CONCLUSION: Characterizing F8 in the 1000G project highlighted the complexity of F8 variants and the importance of interrogating genetic variants on multiple ethnic backgrounds for associations with bleeding and thrombosis. The haplotype analysis and the orientation of duplicons that flank the large deletion suggested that the deletion was recurrent and originated by homologous recombination.

FVIII inhibitors: pathogenesis and avoidance.

The pathogenesis of inhibitory antibodies has been the focus of major scientific interest over the last decades, and several studies on underlying immune mechanisms and risk factors for formation of these antibodies have been performed with the aim of improving the ability to both predict and prevent their appearance. It seems clear that the decisive factors for the immune response to the deficient factor are multiple and involve components of both a constitutional and therapy-related nature. A scientific concern and obstacle for research in the area of hemophilia is the relatively small cohorts available for studies and the resulting risk of confounded and biased results. Careful interpretation of data is recommended to avoid treatment decisions based on a weak scientific platform. This review will summarize current concepts of the underlying immunological mechanisms and risk factors for development of inhibitory antibodies in patients with hemophilia A and discuss how these findings may be interpreted and influence our clinical management of patients.

Genetic risk factors for inhibitors in haemophilia A.

The current most serious side effect of haemophilia treatment is inhibitor development. Significant progress has been made over the last decades to understand why this complication occurs in some patients and it seems clear that both genetic and non-genetic factors are involved. Several issues however remain to be settled. A review was undertaken to summarise some key findings regarding the current view and available data on genetic markers of potential importance within this area. The causative F8 mutation, together with the HLA class II alleles, plays a pivotal pathophysiological role in inhibitor development. The types of mutation most frequently associated with inhibitors are large deletions, nonsense mutations, inversions, small deletions/insertions without A-runs, splice-site mutations at conserved nucleotides and certain missense mutations. Regarding HLA class II allele, it has been hard to consistently identify risk alleles. Ethnicity has consistently been associated with inhibitor risk, but the causality of this has so far not been resolved. Among immune regulatory molecules, several polymorphic molecules have been suggested to be of importance. Most of these need additional studies and immune system challenges have to be fully evaluated. Inhibitor risk should be further defined, as patients in the future may be offered non-immunogenic treatments.

Detection of hemophilia a carriers in Azeri Turkish population of Iran: usefulness of HindIII and BclI markers.

Hemophilia A (HA) is an inherited X-linked coagulation disorder caused by the deficiency of factor VIII (FVIII). Linkage analysis is a common indirect method for the detection of female carriers in families with HA. In the current study, 173 patients from 30 unrelated families with HA were recruited from the Azeri Turkish population of northwest Iran and analyzed for BclI and HindIII markers by polymerase chain reaction-restriction fragment length polymorphism. We investigated the potential of using these markers for the detection of mutation in carriers through linkage analysis, which would be of tremendous use in prenatal diagnosis. Among the tested women, 47% and 35% were found to be heterozygous for BclI and HindIII polymorphic markers, respectively. The BclI and HindIII markers were informative for the detection of 63% and 17% potential carriers, respectively, demonstrating the effectiveness of the BclI marker for the detection of HA carriers among the Azeri Turkish population.

Genetic factors influencing inhibitor development in a cohort of South African haemophilia A patients.

A critical complication of factor VIII (FVIII) replacement therapy in Haemophilia A (HA) treatment is inhibitor development. Known genetic factors predisposing to inhibitor development include FVIII (F8) gene mutations, ethnicity, a family history of inhibitors and FVIII haplotype mismatch. The aim of this study was to characterize and correlate these genetic factors in a cohort of South African HA patients. This was a retrospective study that included 229 patients and involved the analysis of patient files, HA molecular and clinical databases and molecular analysis of the F8 gene haplotype. Of the 229 patients, 51% were of black ethnicity, 49% were white, 5% had mild HA, 4% were moderate and 91% were severe, 36% were int22 positive and 13% were inhibitor positive. Of the inhibitor positive patients, 72% were black patients. Inhibitors were reported in 27% of black int22 positive patients, 13% of black int22 negative patients, 9% of white int22 positive patients and 7% of white int22 negative. The H1 haplotype was more common in whites (75%) and H2 was more common in blacks (74%). H3 and H5 were only found in black patients and had a higher frequency of inhibitor development than H1 and H2. In this small HA cohort, black patients had a significantly higher frequency of inhibitor development and the results were indicative of an association between inhibitor development, ethnicity and haplotype.

Prevalence, incidence, and factor concentrate usage trends of hemophiliacs in Taiwan.

PURPOSE: Hemophilia A and B (HA, HB) are the most common X-linked inherited bleeding disorders. The introduction of factor concentrates has allowed for control of the lifelong chronic disease. However, no studies have been published regarding the epidemiology of hemophilia in Taiwan. Our aim was to determine the prevalence, incidence, and mortality rate, as well as trends in the use of factor concentrates, in individuals with hemophilia in Taiwan. MATERIALS AND METHODS: A retrospective study was conducted using the National Health Insurance Research Database between 1997 and 2007. RESULTS: We identified 988 males with hemophilia (HA : HB ratio=5.4 : 1). The mean prevalence per 100000 males was 6.7 ± 0.1 for HA and 1.2 ± 0.1 for HB. The estimated mean annual incidence per live male birth was 1 in 10752 for HA and 1 in 47619 for HB. Standardized mortality ratios for males with hemophilia (all severities) or severe hemophilia were 1.3- and 2.1-fold higher than that of the general male population, respectively. Mean factor VIII (FVIII) and factor IX (FIX) usage was 1.5003 ± 0.4029 and 0.3126 ± 0.0904 international units (IUs) per capita, respectively. Mean FVIII and FIX usage per patient with hemophilia (all severities) or severe hemophilia was 44027 ± 11532 and 72341 ± 17298, respectively, and 49407 ± 13015 and 74369 ± 18411 IUs per person with HA or HB, respectively. CONCLUSION: Our data revealed epidemiologic and factor concentrate usage trends in males with hemophilia in Taiwan, highlighting a need for improvements in the mandatory National Health Insurance registry. A better- designed, patient-centered registry system would enable more detailed patient information collection and analysis, improving subsequent care.

Experience of Advate rAHF-PFM in previously untreated patients and minimally treated patients with haemophilia A.

We report a prospective trial of 55 previously untreated patients (PUPs) and minimally treated patients (MTPs) with severe/moderately severe haemophilia A (baseline factor VIII [FVIII] ≤2%) treated with a single FVIII replacement product. It was the objective of this study to evaluate the immunogenicity, efficacy, and safety of rAHF-PFM (Advate®). On-demand or prophylactic treatment regimens were determined at the discretion of the investigator. rAHF-PFM was also permitted for perioperative management. There were 633 bleeding episodes (BEs), including 517 treated, and 466 rated for efficacy. Haemostatic efficacy was considered excellent/good in 93% of 466 rated treatments. Of 517 treated BEs, 463/517 (90%) were managed with one (356/517 [69%]) or two infusions (107/517 [21%]). There were 27 surgeries. Intraoperative (n=22) and postoperative (n=25) haemostatic efficacies were considered excellent or good in 100% of rated surgeries. Related serious adverse events (SAEs) were inhibitor development in 16/55 (29.1%) subjects who received at least one infusion of rAHF-PFM. Non-serious, related adverse events (AEs) were few in number (14 in eight subjects). The odds ratio (OR [95% Confidence Interval, CI]) of developing inhibitors was significantly higher in subjects with a family history of inhibitor (4.95[1.29-19.06]), non-Caucasian ethnicity (4.18, [1.18-14.82]), and intensive treatment at high dose (4.5 [1.05-19.25]) within ≤20 exposure days (EDs). In conclusion, rAHF-PFM was safe and effective for the management and perioperative coverage of PUPs/MTPs with severe/moderately severe haemophilia A. This report supports previous findings from studies in which family history of inhibitor, non-Caucasian ethnicity, and high intensity treatment were associated with high risk of inhibitor development.

Increased prevalence of inhibitors in Hispanic patients with severe haemophilia A enrolled in the Universal Data Collection database.

Neutralizing inhibitors develop in 20-30% of patients with severe factor VIII (FVIII) deficiency. It is well established that Blacks have a higher prevalence of inhibitors than Whites. This is the first study to definitively demonstrate increased inhibitor prevalence in the Hispanic population. We compared inhibitor prevalence among various racial and ethnic groups in a cross-sectional analysis of 5651 males with severe haemophilia A that participated in the Universal Data Collection project sponsored by the Centers for Disease Control and Prevention. We used logistic regression analysis to control for potential confounding variables. We assigned as Hispanic those participants who were white and labelled themselves Hispanic. The prevalence of high-titre inhibitors in the Hispanic participants was 24.5% compared to 16.4% for White non-Hispanic patients (OR 1.4, 95% CI 1.1, 1.7). Possibilities as to the underlying cause of increased inhibitor prevalence in minority ethnic populations include polymorphisms in the FVIII molecule, HLA subtypes and differing inflammatory responses. A better understanding may lead to tailored treatment programmes, or other therapies, to decrease or prevent inhibitor development.

F8 and F9 mutations in US haemophilia patients: correlation with history of inhibitor and race/ethnicity.

Both genetic and treatment-related risk factors contribute to the development of inhibitors in haemophilia. An inhibitor surveillance system piloted at 12 US sites has the goal of assessing risk factors through prospective data collection. This report examines the relationship of genotype and race/ethnicity to history of inhibitor in a large cohort of US haemophilia patients. Mutation analysis was performed on 676 haemophilia A (HA) and 153 haemophilia B (HB) patients by sequencing, Multiplex Ligation-dependent Probe Amplification, and PCR for inversions in F8 introns 22 (inv22) and 1 (inv1). Two HB patients with deletions had history of inhibitor. In severe HA, frequency of history of inhibitor was: large deletion 57.1%, splice site 35.7%, inv22 26.8%, nonsense 24.5%, frameshift 12.9%, inv1 11.1% and missense 9.5%. In HA, 19.6% of 321 White non-Hispanics (Whites), 37.1% of 35 Black non-Hispanics (Blacks) and 46.9% of 32 Hispanics had history of inhibitor (P = 0.0003). Mutation types and novel mutation rates were similar across ethnicities. When F8 haplotypes were constructed, Whites and Hispanics showed only H1 and H2. Within H1, history of inhibitor was 12.4% in Whites, 40.0% in Blacks (P = 0.009) and 32.4% in Hispanics (P = 0.002). Inhibitor frequency is confirmed to vary by mutation type and race in a large US population. White patients with history of inhibitor did not exhibit rare F8 haplotypes. F8 gene analysis did not reveal a cause for the higher inhibitor frequencies in Black and Hispanic patients.

Assessing the impact of age, race, ethnicity and inhibitor status on functional limitations of patients with severe and moderately severe haemophilia A.

Few data exist on the impact of age and inhibitor status on activity levels among patients with severe and moderately severe haemophilia A. The aim of this analysis was to assess the impact of age, race/ethnicity and inhibitor status on functional limitations through retrospective analysis of data from the Hemophilia and Thrombosis Research Society (HTRS) Registry. Functional status data from patients with haemophilia A with or without inhibitors who were enrolled in the HTRS Registry between October 1999 and July 2008 were analysed by age, race and ethnicity. Of the 2497 registrants, 1340 had congenital haemophilia A (333 with inhibitors). Functional status was available for 274 subjects with haemophilia A with current inhibitors and 247 subjects without inhibitors who had moderately severe (FVIII levels ≤ 2%). Functional impairment increased with age across five levels of functional status (P < 0.01). Inhibitors were associated with greater functional impairment in two age groups (13-21 years and older than 21 years) [unrestricted activity in 57.8% vs. 63.6% (P = 0.06) and 18.3% vs. 28.6% (P = 0.04), respectively]. Blacks had worse functional status than caucasians across all ages regardless of inhibitor status. Functional status decreases with age, and impairment is greater among patients with inhibitors beginning in adolescence. These results reaffirm the need for early eradication of inhibitors and early treatment of bleeds in inhibitor and non-inhibitor patients. This analysis highlights the benefit of ongoing study of these patients through data collected for the HTRS Registry.