Identifying hemophilia B carriers: Utility of aPTT, factor IX levels and ratios of factor IX to other Vitamin K dependent factors.

INTRODUCTION: Diagnosing hemophilia B (HB) carrier status is important to manage bleeding in carriers and to prevent bleeding in potential offspring. Without a family history of hemophilia, diagnosing HB carrier status is challenging. Genetic testing is the gold-standard, however it is reserved for individuals with a high suspicion of carrier status. AIMS: To describe the distribution of activated partial thromboplastin time (aPTT) and factor IX coagulant (FIX:C) levels in HB carriers and assess the ratio of FIX:C to other Vitamin K dependent factors (FII:C, FVII:C, FX:C) as an indicator of HB carrier status. METHODS: In this retrospective, single-centre cohort study, subjects were included if they were obligate or genetically proven HB carriers. Distributions of aPTT and FIX:C were described and the relationship between FIX:C levels in carriers and severity of familial HB was analysed. Ratios of FIX:C to FII:C, FVII:C, FX:C were calculated. RESULTS: Seventy-two female HB carriers (median age: 34 years; IQR 24-43) were included. Median aPTT and FIX:C levels were 33.0 s [IQR 30.0-37.0] and 57 IU/dL [IQR 43-74]. Fifteen carriers (21%) had mild HB (FIX:C levels of 10-40 IU/dL). FIX:C levels trended higher in carriers of mild HB versus carriers of moderate/severe HB. In six carriers, the median ratio of FIX:C to other Vitamin K dependent factors was 0.44, with 92% of ratios being ≤ 0.75. CONCLUSION: aPTT and FIX:C levels were unreliable in diagnosing HB carrier status. A low ratio of FIX:C to other Vitamin K dependent factors may be a useful marker of HB carrier status.

Unravelling the effect of blood group on FVIII:C levels and response to DDAVP in 20 males with a single genotype (Twillingate Variant) causing Haemophilia A.

INTRODUCTION: The genetic variant responsible for haemophilia A (HA) significantly impacts endogenous coagulant factor VIII (FVIII:C) level, thus impacting DDAVP responsiveness. Blood group (BG) also impacts FVIII:C levels, but this is difficult to evaluate in a genetically heterogeneous population. Canada has a large cohort of mild-moderate HA due to a single point variant: c.6104T>C, p.Val2035Ala-the Twillingate variant. AIM: To evaluate the impact of BG on endogenous FVIII:C levels and DDAVP responsiveness in a single genotype of mild-moderate HA. METHODS: This was a retrospective, single-centre study. BG and FVIII:C levels were obtained for males with the Twillingate variant. One-hour absolute and fold increases in FVIII:C post-DDAVP were calculated. T-tests and Mann-Whitney U tests were used to compare FVIII:C levels and DDAVP challenge variables between individuals according to BGs (O vs. non-O). RESULTS: Twenty males were included. There were significant differences between BGs (O vs. non-O) in their lowest FVIII:C level at age <12 years (medians: 0.05 vs. 0.08 IU/mL; P = .05). Fifteen subjects underwent DDAVP challenges. Mean 1-h FVIII:C were 0.29 (O BG) versus 0.41 IU/mL (non-O BG); P = .04. There were no significant differences between BGs (O vs. non-O) in mean absolute FVIII:C increase (0.20 vs. 0.27 IU/mL; P = .10) and FVIII:C fold increase (3.3-fold vs. 3.8-fold; P = .51). CONCLUSION: In HA subjects with an identical genotype, BG significantly impacts baseline FVIII:C levels and FVIII:C levels post-DDAVP, but does not impact absolute and fold increases in FVIII:C with DDAVP.

Excess weight gain in the paediatric bleeding disorders population: Impact of the COVID-19 Pandemic.

INTRODUCTION: The COVID-19 pandemic has resulted in lifestyle changes for children. The aim of this study was to evaluate the impact of the pandemic on weight/BMI in children with severe bleeding disorders. METHODS: We conducted a retrospective review of patients age 3-18 years with severe bleeding disorders on prophylactic therapy treated at SickKids Hospital (Toronto, Canada) between February 01, 2018 and March 31, 2021. We evaluated the following pre- and post-COVID variables: weight (kg), weight percentile, BMI (kg/m2 ), BMI percentile, HJHS score, and prophylactic dosing (units/kg). RESULTS: One hundred and four patients were included in the final analysis. Diagnoses were as follows:  haemophilia A (n = 92; 70.8%), haemophilia B (n = 17; 13.1%), type 3 von Willebrand disease (n = 11; 8.5%), the remainder were diagnosed with rare factor deficiencies.  Median interval time from pre-COVID measurements to latest follow-up was 12.4 months (IQR 10.32-14.52 months) during which there was a statistically significant increase in median weight percentile +5.75 centiles (from 63rd centile to 68.75th centile). There was a statistically significant increase in mean BMI of +1.03 kg/m2 (P = < .001) while median BMI percentile increased +8.82 centiles (from 53.9th centile to 62.72nd centile) and mean BMI percentile increased 3.42 centiles (from 57.5 centile to 60.9 centile). The group that gained the most weight centiles, BMI and BMI centiles were 5-14 years old. CONCLUSION: There was a trend to weight gain over the study period. More long-term data is required to evaluate the impact of this increase in weight and BMI on children with bleeding disorders.

Updating the Canadian hemophilia outcomes-kids life assessment tool (CHO-KLAT Version2.0).

OBJECTIVES: Hemophilia is an X-chromosome-linked disorder associated with recurrent bleeding into muscles and joints, leading to pain and limitations in physical function that may diminish quality of life. The Canadian Hemophilia Outcomes-Kids Life Assessment Tool (CHO-KLAT) is a disease-specific measure of quality of life that was recently revised to facilitate cross-cultural adaptation. This study assessed the validity and reliability of version 2.0 of the CHO-KLAT (CHO-KLAT2.0). METHODS: Content validity was assessed via detailed cognitive debriefing to confirm that Canadian boys understood the CHO-KLAT2.0. The measurement properties of the CHO-KLAT2.0 were assessed in comparison to those of the PedsQL, the Haemo-QoL, and two global ratings. Most children completed the CHO-KLAT2.0 a second time to assess test-retest reliability. RESULTS: Cognitive debriefing was completed with 12 boys (age 8.6-17.8 years) and 9 of their parents and resulted in no substantive changes. Sixty boys (mean age 11.8 years) participated in the validation phase, which showed a mean CHO-KLAT2.0 score of 75.4±12.0, strong correlations with the PedsQL (r = 0.62, P<0.001) and Haemo-QoL (r = 0.64, P<0.001), and moderate correlations with global ratings of hemophilia bother (ρ =-0.39, P = 0.002) and health (ρ =-0.47, P = 0.0002). Test-retest concordance was better among parents (0.79) than among boys (0.63). CONCLUSIONS: This study establishes the measurement properties of the CHO-KLAT2.0. The summary scores are very similar to those from the original development study, and thus, these have not been affected by the revisions. These results provide reference standards for comparing data from other countries to the Canadian experience and to estimate sample sizes for future clinical trials.

Quality of life in childhood immune thrombocytopenia: international validation of the kids' ITP tools.

BACKGROUND: The Kids ITP Tools (KIT) is a disease-specific measure of health-related quality of life for children with immune thrombocytopenia (ITP). To facilitate use in international trials it has been cross-culturally adapted for France, Germany, the United Kingdom and Uruguay. This study assessed the validity and reliability of the translated KIT in comparison to generic quality of life measures. METHODS: Children 2-18 years of age with ITP and their parents were recruited in France, Germany, the United Kingdom and Uruguay. Participants completed the KIT, PedsQL and KINDL. We examined the Pearson's correlation between these measures for our pooled sample and estimated the reliability over a 2-week time period. Findings were further explored by country. RESULTS: A total of 127 families (81 children self-reported) participated. Mean child-reported scores were: KIT 74.3 (SD = 15.3), PedsQL 81.3 (SD = 13.0), and KINDL 70.5 (SD = 14.3). Corresponding mean parent proxy-reported scores were: 70.6 (SD = 18.1), 75.7 (SD = 16.8) and 72.3 (SD = 12.7), respectively. Correlation between KIT and the generic measures was consistent with our a priori hypothesis (PedsQL r = 0.54, KINDL r = 0.48, both P < 0.0001). Child KIT scores for newly diagnosed ITP patients were significantly lower than for chronic ITP patients (67.3 vs. 77.3; P = 0.005). There was a significant correlation (P < 0.001) between the child and parent proxy KIT scores (ICC = 0.52). Child KIT test-retest reliability was acceptable at 0.71. CONCLUSIONS: The cross-culturally translated KIT is valid and reliable with acceptable correlation to the PedsQL and KINDL. There is a significant difference in child self-reported KIT scores between newly diagnosed and chronic ITP.

Updating the Canadian Hemophilia Outcomes-Kids' Life Assessment Tool (CHO-KLAT) in the era of extended half-life clotting factor concentrates.

INTRODUCTION: The purpose of this study was to review and update the content of the Canadian Hemophilia Outcomes-Kids' Life Assessment Tool version 2.0 (CHO-KLAT), in the context of extended half-life (EHL) factor concentrates (FCs) and to establish the validity and reliability of the updated CHO-KLAT. METHODS: Focus groups were conducted with boys with hemophilia, their parents, and health care providers across Canada to review the CHO-KLAT v2.0 and determine if any modifications were required. The validity of the revised CHO-KLAT (version 3.0) was then determined in a sample of boys with hemophilia and their parents by calculating its correlation with the Pediatric Quality of Life Core Module (PedsQL-Core). Test-retest reliability was assessed using an intraclass correlation coefficient (ICC). RESULTS: Thirteen focus groups at 5 pediatric hemophilia treatment centers (HTCs) (n = 71) resulted in 19 changes to the CHO-KLAT v2.0, generating a revised 40-item CHO-KLAT, the CHO-KLAT v3.0. Thirty-five boys with hemophilia (median age, 14; range, 7-17 years) and 47 parents participated in the validation of the CHO-KLAT v3.0. There was a moderate correlation between the CHO-KLAT v3.0 child self-report and PedsQL-Core (r = 0.56, P = .01), and a strong correlation between the CHO-KLAT v3.0 parent-proxy and PedsQL-Core (r = .79, P = .0007). The test-retest reliability ICC was 0.90 for the child self-report CHO-KLAT v3.0 and 0.68 for the parent-proxy CHO-KLAT v3.0. CONCLUSION: The CHO-KLAT v3.0 is a reliable and valid child-centric tool that effectively measures health-related quality of life in boys with hemophilia who are receiving standard half-life or EHL FCs.

Measuring the impact of hemophilia on families: Development of the Hemophilia Family Impact Tool (H-FIT).

INTRODUCTION: This study aimed to assess the impact of hemophilia on families, in the context of current and emerging hemostatic therapies, and explore the need for a hemophilia-specific tool targeted at parents of boys aged <4 years. A secondary aim was to develop and validate the new tool. METHODS: Focus groups were conducted with parents of boys with hemophilia and hemophilia health care providers at Canadian hemophilia treatment centers (HTCs) to review the relevance of the Pediatric Quality of Life Family Impact Module (PedsQL-FIM); a novel questionnaire was developed by identifying core themes expressed. This questionnaire, the Hemophilia Family Impact Tool (H-FIT) was validated in a sample of parents of boys with hemophilia relative to the PedsQL-FIM. RESULTS: Seven focus groups were conducted at four HTCs, generating themes specific to hemophilia not covered by the PedsQL-FIM, suggesting that a new tool be developed (the H-FIT). In the validation phase, 54 parents completed the H-FIT and PedsQL-FIM. The H-FIT had a strong correlation with the PedsQL-FIM across all ages (r = 0.79; P < .0001) and a moderate correlation for parents of boys aged <7 years (r = 0.64; P = .0007). There was a significant difference between the mean H-FIT scores for parents of boys using extended half-life factor (68.1; standard deviation [SD]=14.2) compared to standard half-life factor (54.7; SD=18.4; P = .04). CONCLUSION: A novel, disease-specific tool, the H-FIT, has been developed to measure the impact of hemophilia on families. The H-FIT has good preliminary measurement properties and may be responsive to changes in therapy associated with a decreased burden of administration.

IVMP+IVIG raises platelet counts faster than IVIG alone: results of a randomized, blinded trial in childhood ITP.

Children with immune thrombocytopenia (ITP) rarely suffer from life-threatening bleeds (eg, intracranial hemorrhage). In such settings, the combination of IV methylprednisolone (IVMP) with IV immune globulin (IVIG) is used to rapidly increase platelet counts (PCs). However, there are no controlled data to support using combination therapy over IVIG alone. We conducted a randomized, double-blind, placebo-controlled study to evaluate the rapidity of the PC increment and associated adverse events (AEs) between 2 regimens: A (IV placebo) and B (IVMP 30 mg/kg), both given over 1 hour, followed in both cases by IVIG (Gamunex 10%) 1 g/kg over 2-3 hours in children 1-17 years old with primary ITP and PCs <20 × 109/L in whom physicians had decided to treat with IVIG. Thirty-two children (ages: median, 8 years; range, 1.2-17.5 years) with a mean baseline PC of 9.2 × 109/L participated. Eighteen were randomized to regimen A and 14 to regimen B. By 8 hours after initiating therapy, 55% of all children had a PC ≥20 × 109/L (no group difference). By 24 hours, mean PCs were 76.9 × 109/L (B) vs 55 × 109/L (A) (P = .06; P = .035 when adjusted for intergroup differences in patient ages). No patient experienced severe bleeding/unexpected severe AEs. There were statistically fewer IVIG-related headaches in the group receiving combination therapy (P = .046). Our findings show a rapid response to IVIG with/without steroids and provide evidence to support the use of IVMP+IVIG in life-threatening situations. This trial was registered at www.clinicaltrials.gov as #NCT00376077.

Measuring disease-specific quality of life in rare populations: a practical approach to cross-cultural translation.

BACKGROUND: Disease-specific quality of life (QoL) measures have enhanced the capacity of outcome measures to evaluate subtle changes and differences between groups. However, when the specific disease is rare, the cohort of patients is small and international collaboration is often necessary to accomplish meaningful research. As many of the QoL measures have been developed in North American English, they require translation to ensure their usefulness in a multi-cultural and/or international society. Published guidelines provide formal methods to achieve cross-culturally comparable versions of a QoL tool. However, these guidelines describe a rigorous process that is not always feasible, particularly in rare disease groups. The objective of this manuscript is to describe the process that was developed to achieve accurate cross-cultural translations of a disease-specific QoL measure, to overcome the challenges of a small sample size, i.e. children with a rare disorder. PROCEDURE: A measurement study was conducted in the United Kingdom (UK), France, Germany and Uruguay, during which the validated measure was translated into the languages of the respective countries. RESULTS: This is a report of a modified, child-centric, cross-cultural translation and adaptation process in which culturally appropriate and methodologically valid translations of a disease-specific QoL measure, the Kids' ITP Tools (KIT), were performed in children with immune thrombocytopenic purpura (ITP). The KIT was translated from North American English into UK English, French, German, and Spanish. CONCLUSION: This study was a successful international collaboration. The modified process through which culturally appropriate and methodologically valid translations of QoL measures may be achieved in a pediatric population with a relatively rare disorder is reported.

Impact of prophylaxis on health-related quality of life of boys with hemophilia: An analysis of pooled data from 9 countries.

BACKGROUND: Prophylaxis reduces the frequency of bleeds in boys with severe hemophilia and is the standard care for their management in resource-abundant countries. The effect of prophylaxis on Health-Related Quality of Life (HRQoL) has not been established, because the sample sizes of most studies are too small to explore the relationship of multiple factors that influence HRQoL. METHODS: The aim of this study was to assess the impact of hemophilia severity and treatment regimen on HRQoL and to establish the minimum important difference (MID) using the international level of score distributions. HRQoL data were pooled from 7 studies across 9 countries. HRQoL was measured using the Canadian Hemophilia Outcomes-Kids' Life Assessment Tool (CHO-KLAT). A mixed-effect linear regression analysis was employed to assess the impact of prophylaxis on the CHO-KLAT score. RESULTS: Data from 401 boys with hemophilia were analyzed (57.6% severe hemophilia and 57.6% receiving prophylaxis). The model revealed that receiving prophylaxis was significantly associated with higher HRQoL (regression coefficient 8.5, 95% confidence interval [CI] 3.9-13.1). Boys with severe hemophilia had a significantly lower HRQoL as compared to boys with moderate and mild hemophilia whose CHO-KLAT scores were 7.0 and 6.6 points higher, respectively. There was a significant interaction between treatment and disease severity (P = 0.023), indicating prophylaxis has the most significant impact in boys with severe hemophilia. Based on these pooled data, the MID of the CHO-KLAT was established at 6.5. CONCLUSIONS: This study confirms the positive effect of prophylaxis on HRQoL in boys with hemophilia in a real-world setting and provides initial benchmarks for interpreting HRQoL scores based on use of the CHO-KLAT instrument.

Validity, reliability, and responsiveness of a new measure of health-related quality of life in children with immune thrombocytopenic purpura: the Kids' ITP Tools.

OBJECTIVE: To refine the disease-specific health-related quality of life measure in immune (idiopathic) thrombocytopenic purpura (ITP) and to determine its validity, reliability, and responsiveness to change. STUDY DESIGN: The initial phase involved cognitive debriefing of 12 families, on the basis of which the measure was modified and then named Kids' ITP Tools (KIT). The measure was administered on 2 occasions with the Pediatric Quality of Life Inventory (PedsQL) to 41 patients with acute ITP and 49 patients with chronic ITP, 2 to 18 years old, and their parents (proxy-respondents) at 6 North American centers. RESULTS: Patients with acute ITP had lower scores when compared with patients with chronic ITP (child 64 versus 76, proxy 69 versus 77). The KIT moderately correlated with the PedsQL. Child versus proxy KIT scores showed moderate correlation, and the KIT was superior to the PedsQL. Test-retest reliability was substantial in the child report, but only moderate for the proxy report, similar to the PedsQL. The KIT showed a mean score change of 13 in the child and 15 in the proxy, which was greater than the PedsQL child's change of 7 and proxy change of 5. CONCLUSION: The KIT is valid, with good distinction between acute and chronic ITP and a moderate correlation with the PedsQL. The KIT demonstrated reliability comparable with that of the PedsQL, yet it was more responsive to change. Therefore the KIT can be used as an outcome measure in future clinical trials of childhood ITP.

How well does the Canadian Haemophilia Outcomes-Kids' Life Assessment Tool (CHO-KLAT) measure the quality of life of boys with haemophilia?

BACKGROUND: It is important to measure the quality of life (QoL) of boys with haemophilia, because the diagnosis has a significant impact on their lives and this impact fluctuates over time. A disease-specific measure of QoL is required because the aspects of life that are affected by haemophilia may differ from those assessed by generic QoL measures. This paper describes the final phase of development of a disease-specific measure of QoL for boys with haemophilia: the Canadian Haemophilia Outcomes-Kids Life Assessment Tool (CHO-KLAT). PROCEDURE: A 79-item version of the CHO-KLAT was administered to 52 children. A detailed item analysis was conducted to shorten the CHO-KLAT. The reliability of the revised version was assessed using intraclass correlation coefficients. Validity was assessed by comparing it to the PedsQL and the HaemoQoL. RESULTS: The item analysis resulted in the retention of 35 strongly performing items (CHO-KLAT(35)). These items were aggregated into the CHO-KLAT(35) summary score. Repeated measures reliability of the CHO-KLAT(35) was 0.74 for children and 0.83 for parents, and the child-parent concordance was 0.75. The validity of the CHO-KLAT(35) was confirmed by a correlation of 0.78 with the Haemo-QoL and of 0.59 with the PedsQL. CONCLUSIONS: The CHO-KLAT(35) is a reliable and valid measure of QoL for boys with haemophilia.

Fcgamma receptor IIa and IIIa polymorphisms in childhood immune thrombocytopenic purpura.

Fcgamma receptor-mediated destruction of autoantibody-sensitized platelets is central to the immune pathophysiology of childhood immune thrombocytopenic purpura (ITP). Allelic variants exist among the random population for some Fcgamma receptors. The variants represent single nucleotide polymorphisms, leading to functional differences in the ability to bind immunoglobulin (Ig)G or IgG subclasses. The genotypic frequencies for two Fcgamma receptor single nucleotide polymorphisms, FcgammaRIIa-131 arginine (R) versus histidine (H) and FcgammaRIIIa-158 valine (V) versus phenylalanine (F) were examined in 98 children diagnosed with childhood ITP. The genotype frequencies were compared with those of 130 healthy control subjects. Chi-square analysis was used to determine whether the allelic frequencies of the high-affinity receptor variants were associated with childhood ITP. Both the FcgammaRIIa-131H and the FcgammaRIIIa-158V were significantly over-represented in children with ITP versus the control subjects (P-values 0.03). The same statistical difference was noted with the combined FcgammaRIIa-131H and FcgammaRIIIa-158V allelic gene frequencies. There was no statistical difference between children who later developed chronic ITP compared with children with acute ITP, suggesting that additional factors are responsible for the development of the chronic form of the disease. These observations underscore the importance of Fcgamma receptor-mediated cell clearance in childhood ITP.

Development of disease-specific health-related quality-of-life instruments for children with immune thrombocytopenic purpura and their parents.

PURPOSE: Immune thrombopenic purpura (ITP) is an important childhood hematologic disorder that is often frightening to patients and their parents because of its acute onset and bleeding symptoms. There is no consensus on the management of ITP in children. Pediatric hematologists have differing management philosophies, yet most, explicitly or implicitly, incorporate into their management approach the potential impact on the child's and family's quality of life. There is no validated ITP-specific health-related quality-of-life instrument for use with children with ITP, nor is there one to evaluate the burden experienced by their parents. ITP is usually a self-limited disorder. With current controversy over management approaches, an evaluation of the disease burden experienced by the child and the family may assist with the assessment of alternative treatment approaches. METHODS: Using standard clinimetric methodology, 88 children with acute or chronic ITP, along with their parents, participated in the development of the instruments. RESULTS: The 26-item ITP-Child Quality-of-Life Questionnaire includes five domains: treatment side effect-related, intervention-related, disease-related, activity-related, and family-related. This instrument can be used as a self-completed instrument for most children older than 7 years or as a proxy-completed instrument by parents of children younger than 7 years. The 26-item ITP-Parental Burden Quality-of-Life Questionnaire includes six domains: concerns related to diagnosis/investigation, treatment/disease monitoring, monitoring of child's activities, interference with daily life, disease outcome, and emotional impacts. CONCLUSIONS: The first steps of the development of these formally developed instruments are complete. The instruments are available for study to validate and test their responsiveness through use in clinical research studies. Such instruments are increasingly recognized as important for comprehensive measurement of patient outcomes in this and other areas of pediatric hematology/oncology practice.

Assessment of thrombocytopenic disorders using the Platelet Function Analyzer (PFA-100).

The Platelet Function Analyzer (PFA-100) was used to measure platelet function in paediatric patients with destructive versus underproduction thrombocytopenia. Closure time (CT) and total volume (TV) measurements with standard 150 microm apertures discriminated between patients with similar platelet counts from 30 to 150 x 10(9)/l. However, at platelet counts < 30 x 10(9)/l, a 100-microm aperture (experimental) gave the best assessment of platelet function. TV results could be analysed even when CTs were indeterminate. Further investigations are warranted to more fully understand the relationships among platelet function as measured by the PFA-100 in standard/experimental modes, bleeding and transfusion outcome in thrombocytopenia.