Efficacy of Early Prophylaxis Against Catheter-Associated Thrombosis in Critically Ill Children: A Bayesian Phase 2b Randomized Clinical Trial.

OBJECTIVES: We obtained preliminary evidence on the efficacy of early prophylaxis on the risk of central venous catheter-associated deep venous thrombosis and its effect on thrombin generation in critically ill children. DESIGN: Bayesian phase 2b randomized clinical trial. SETTING: Seven PICUs. PATIENTS: Children less than 18 years old with a newly inserted central venous catheter and at low risk of bleeding. INTERVENTION: Enoxaparin adjusted to anti-Xa level of 0.2-0.5 international units/mL started at less than 24 hours after insertion of central venous catheter (enoxaparin arm) versus usual care without placebo (usual care arm). MEASUREMENTS AND MAIN RESULTS: At the interim analysis, the proportion of central venous catheter-associated deep venous thrombosis on ultrasonography in the usual care arm, which was 54.2% of 24 children, was significantly higher than that previously reported. This resulted in misspecification of the preapproved Bayesian analysis, reversal of direction of treatment effect, and early termination of the randomized clinical trial. Nevertheless, with 30.4% of 23 children with central venous catheter-associated deep venous thrombosis on ultrasonography in the enoxaparin arm, risk ratio of central venous catheter-associated deep venous thrombosis was 0.55 (95% credible interval, 0.24-1.11). Including children without ultrasonography, clinically relevant central venous catheter-associated deep venous thrombosis developed in one of 27 children (3.7%) in the enoxaparin arm and seven of 24 (29.2%) in the usual care arm (p = 0.02). Clinically relevant bleeding developed in one child randomized to the enoxaparin arm. Response profile of endogenous thrombin potential, a measure of thrombin generation, was not statistically different between trial arms. CONCLUSIONS: These findings suggest the efficacy and safety of early prophylaxis that should be validated in a pivotal randomized clinical trial.

Age-Dependent Heterogeneity in the Efficacy of Prophylaxis With Enoxaparin Against Catheter-Associated Thrombosis in Critically Ill Children: A Post Hoc Analysis of a Bayesian Phase 2b Randomized Clinical Trial.

OBJECTIVES: We explored the age-dependent heterogeneity in the efficacy of prophylaxis with enoxaparin against central venous catheter-associated deep venous thrombosis in critically ill children. DESIGN: Post hoc analysis of a Bayesian phase 2b randomized clinical trial. SETTING: Seven PICUs. PATIENTS: Children less than 18 years old with newly inserted central venous catheter. INTERVENTIONS: Enoxaparin started less than 24 hours after insertion of central venous catheter and adjusted to anti-Xa level of 0.2-0.5 international units/mL versus usual care. MEASUREMENTS AND MAIN RESULTS: Of 51 children randomized, 24 were infants less than 1 year old. Risk ratios of central venous catheter-associated deep venous thrombosis with prophylaxis with enoxaparin were 0.98 (95% credible interval, 0.37-2.44) in infants and 0.24 (95% credible interval, 0.04-0.82) in older children greater than or equal to 1 year old. Infants and older children achieved anti-Xa level greater than or equal to 0.2 international units/mL at comparable times. While central venous catheter was in situ, endogenous thrombin potential, a measure of thrombin generation, was 223.21 nM.min (95% CI, 8.78-437.64 nM.min) lower in infants. Factor VIII activity, a driver of thrombin generation, was also lower in infants by 45.1% (95% CI, 15.7-74.4%). Median minimum platelet count while central venous catheter was in situ was higher in infants by 39 × 103/mm3 (interquartile range, 17-61 × 103/mm3). Central venous catheter:vein ratio was not statistically different. Prophylaxis with enoxaparin was less efficacious against central venous catheter-associated deep venous thrombosis at lower factor VIII activity and at higher platelet count. CONCLUSIONS: The relatively lesser contribution of thrombin generation on central venous catheter-associated thrombus formation in critically ill infants potentially explains the age-dependent heterogeneity in the efficacy of prophylaxis with enoxaparin.

Venous Thromboembolism in Pediatric Inflammatory Bowel Disease: A Case-Control Study.

OBJECTIVES: Inflammatory bowel disease (IBD) is associated with increased risk of venous thromboembolism (VTE). Despite this recognized risk, there are limited data and no anticoagulation guidelines for hospitalized pediatric IBD patients. The objectives of this study were to characterize pediatric IBD patients with VTE and determine risk factors. METHODS: This was a nested case-control study comparing hospitalized children with IBD diagnosed with VTE to those without VTE over a decade at a large referral center. Standard descriptive statistics were used to describe the VTE group. Multivariable conditional logistic regression was used to assess risk factors. RESULTS: Twenty-three cases were identified. Central venous catheter (CVC) presence (odds ratio [OR] 77.9; 95% confidence interval [CI]: 6.9--880.6; P < 0.001) and steroid use (OR 12.7; 95% CI: 1.3--126.4; P = 0.012) were independent risk factors. Median age at VTE was 17 years (interquartile range [IQR] 13.5--18.2), and in 48%, VTE was the indication for admission. Median duration of anticoagulation was 3.8 months (IQR 2.3--7.6), and there were no major bleeding events for patients on anticoagulation. There were no patients with known sequelae from VTE, though 22% had severe VTE that required interventions. CONCLUSIONS: Pediatric patients with IBD are at risk for VTE, although the absolute risk remains relatively low. The safety and efficacy of pharmacologic thromboprophylaxis needs to be further evaluated in this population with attention to risk factors, such as steroid use and presence of CVC.

Long-Term Follow-Up of the First in Human Intravascular Delivery of AAV for Gene Transfer: AAV2-hFIX16 for Severe Hemophilia B.

Adeno-associated virus (AAV) vectors are a leading platform for gene-based therapies for both monogenic and complex acquired disorders. The success of AAV gene transfer highlights the need to answer outstanding clinical questions of safety, durability, and the nature of the human immune response to AAV vectors. Here, we present longitudinal follow-up data of subjects who participated in the first trial of a systemically delivered AAV vector. Adult males (n = 7) with severe hemophilia B received an AAV2 vector at doses ranging from 8 × 1010 to 2 × 1012 vg/kg to target hepatocyte-specific expression of coagulation factor IX; a subset (n = 4) was followed for 12-15 years post-vector administration. No major safety concerns were observed. There was no evidence of sustained hepatic toxicity or development of hepatocellular carcinoma as assessed by liver transaminase values, serum α-fetoprotein, and liver ultrasound. Subjects demonstrated persistent, increased AAV neutralizing antibodies (NAbs) to the infused AAV serotype 2 (AAV2) as well as all other AAV serotypes tested (AAV5 and AAV8) for the duration of follow-up. These data represent the longest available longitudinal follow-up data of subjects who received intravascular AAV and support the preliminary safety of intravascular AAV administration at the doses tested in adults. Data demonstrate, for the first time, the persistence of high-titer, multi-serotype cross-reactive AAV NAbs for up to 15 years post- AAV vector administration. Our observations are broadly applicable to the development of AAV-mediated gene therapy.

Regional variation and cost implications of prescribed extended half-life factor concentrates among U.S. Haemophilia Treatment Centres for patients with moderate and severe haemophilia.

BACKGROUND: Extended half-life (EHL) factor VIII (FVIII) and IX (FIX) products are intended to decrease the burden of prophylaxis for patients with haemophilia A or B. Whether these newer concentrates have led to meaningful clinical practice change remains vague. AIM: To characterize the longitudinal use of standard (SHL) and EHL factor concentrates at haemophilia treatment centres (HTCs), using the ATHNdataset, a US database of 138 ATHN-affiliated HTCs. METHODS: Factor concentrate use among moderate and severe haemophilia A and B patients without inhibitors was analysed at three time points over 18 months. RESULTS: Use of EHL concentrates rose from 10% of patients to 22% during this study. EHL FVIII prophylaxis is prescribed to the minority of patients, 28%; EHL FIX now predominates for prophylaxis, 52%. Rates of prescribed EHL products varied significantly by age group and HTC region. Median prescribed prophylaxis for SHL compared to EHL products was FVIII 6240 and 5200 and FIX 6968 and FIX 3900 IU/kg/y, respectively. On-demand EHL use has grown but has minimal contribution to overall usage (2%). CONCLUSION: Haemophilia treatment centre region and patient age impact the rate of adoption of EHL products; however, EHL prescribing continues to rise nationally, particularly for EHL FIX. Careful attention to annual cost of prophylaxis is imperative as the decrease in median EHL prophylaxis consumption is not offset by the higher unit cost of these products. It is unclear how further growth in use of EHLs will be impacted by emerging non-factor replacement and gene therapies.

A survey of pediatric hematology/oncology specialists regarding management of central line associated venous thrombosis.

Central venous catheters (CVCs) account for the largest proportion of thrombotic events in pediatric patients. Questions remain regarding adequate treatment and prevention methods. We surveyed pediatric hematology/oncology specialists, using hypothetical cases to assess management strategies for acute CVC thrombosis and secondary prevention. Survey respondents varied in the use of the thrombophilia evaluation (33.3%, 41/123) and duration of treatment (6 weeks: 54.1%, 66/122). Secondary CVC prophylaxis was utilized by 36.6% (45/123) of respondents and by 24.4% (30/123) but only if there was a documented thrombophilia. This heterogeneity highlights the need for clinical studies to address these important clinical questions.

IVC filter retrieval in adolescents: experience in a tertiary pediatric center.

BACKGROUND: Inferior vena cava (IVC) filters are commonly implanted with the intent to prevent life-threatening pulmonary embolism in at-risk patients with contraindications to anticoagulation. Various studies have reported increases in the rate of venous thromboembolism within the pediatric population. The utility and safety of IVC filters in children has not yet been fully defined. OBJECTIVE: To describe the technique and adjunctive maneuvers of IVC filter removal in children, demonstrate its technical success and identify complications. MATERIALS AND METHODS: A retrospective 10-year review was performed of 20 children (13 male, 7 female), mean age: 15.1 years (range: 12-19 years), who underwent IVC filter retrieval. Eleven of 20 (55%) were placed in our institution. Electronic medical records were reviewed for filter characteristics, retrieval technique, technical success and complications. RESULTS: The technical success rate was 100%. Placement indications included: deep venous thrombosis with a contraindication to anticoagulation (10/20, 50%), free-floating thrombus (4/20, 20%), post-trauma pulmonary embolism prophylaxis (3/20, 15%) and pre-thrombolysis pulmonary patient (1/20, 5%). The mean implantation period was 63 days (range: 20-270 days). Standard retrieval was performed in 17/20 patients (85%). Adjunctive techniques were performed in 3/20 patients (15%) and included the double-snare technique, balloon assistance and endobronchial forceps retrieval. Median procedure time was 60 min (range: 45-240 min). Pre-retrieval cavogram demonstrated filter tilt in 5/20 patients (25%) with a mean angle of 17° (range: 8-40). Pre-retrieval CT demonstrated strut wall penetration and tip embedment in one patient each. There were two procedure-related complications: IVC mural dissection noted on venography in one patient and snare catheter fracture requiring retrieval in one patient. There were no early or late complications. CONCLUSION: In children, IVC filter retrieval can be performed safely but may be challenging, especially in cases of filter tilt or embedding. Adjunctive techniques may increase filter retrieval rates.

Incidence, Management, and Outcomes of Pulmonary Embolism at Tertiary Pediatric Hospitals in the United States.

Background: Pediatric pulmonary embolism (PE) is rare and potentially life-threatening. Though thrombolysis and thrombectomy are increasingly used in adult PE, trends in pediatric treatment and outcomes remain incompletely described. Objectives: The purpose of this study was to describe the incidence of PE, proportion of cases treated with anticoagulation alone, systemic thrombolysis, and directed therapy (local thrombolysis and thrombectomy), clinical outcomes, and total costs. Methods: A multicenter observational study was performed using administrative data from the Pediatric Health Information System database to study PE treated at U.S. pediatric hospitals from 2015 to 2021. Outcomes by treatment were evaluated using multivariable generalized linear mixed effects models. Results: Of 3,136 subjects, 70% were at least 12 years of age, and 46% were male. Sixty-two percent had at least 1 comorbidity, and congenital heart disease of any kind was the most prevalent (20%). Eighty-eight percent of subjects received anticoagulation alone, 7% received systemic thrombolysis, and 5% received directed therapy. Overall in-hospital mortality was 7.5%. Treatment approach did not change over time (P = 0.98). After adjusting for patient characteristics, directed therapy was associated with a lower risk of mortality (adjusted percentage -3%, [95% CI: -5% to 0%]) than anticoagulation alone. Systemic thrombolysis was associated with a greater total cost of hospitalization ($113,043 greater [95% CI: $62,866, $163,219]). Length of hospital stay did not differ by treatment. Conclusions: Pediatric patients with PE have a high incidence of underlying chronic disease. Anticoagulation alone remains the mainstay of treatment, with thrombolysis and thrombectomy rarely being used. Given the relative rarity of pediatric PE, additional research requiring innovative study designs is paramount.

Off-label recombinant factor VIIa use and thrombosis in children: a multi-center cohort study.

OBJECTIVE: To describe the off-label use of recombinant factor VIIa (rFVIIa) in tertiary care pediatric hospitals across the United States and to assess thrombotic events. STUDY DESIGN: A retrospective multi-center cohort study using the Pediatric Health Information System administrative database. Children 18 years of age or younger who received rFVIIa between 2000 and 2007 were included. A label admission was defined as an admission with an International Classification of Diseases diagnostic code for hemophilia or factor VII deficiency; admissions without these codes were classified as off-label. RESULTS: There were 4942 rFVIIa admissions, representing 3764 individual subjects; 74% (3655) of the admissions were off-label. There was a 10-fold increase in the annual rate of off-label admissions from 2000 to 2007 (from 2 to 20.8 per 10 000 hospital admissions, P < .001). The mortality rate in the off-label group was 34% (1258/3655). Thrombotic events occurred in 10.9% (399/3655) of the off-label admissions. CONCLUSIONS: The off-label use of rFVIIa in hospitalized children is increasing rapidly despite the absence of adequate clinical trials demonstrating safety and efficacy. Thrombotic events are common and mortality is high among patients receiving off-label rFVIIa. Further studies are warranted to determine whether these adverse events are attributable to rFVIIa.

Evolutionary insights into coagulation factor IX Padua and other high-specific-activity variants.

The high-specific-activity factor IX (FIX) variant Padua (R338L) is the most promising transgene for hemophilia B (HB) gene therapy. Although R338 is strongly conserved in mammalian evolution, amino acid substitutions at this position are underrepresented in HB databases. We therefore undertook a complete 20 amino acid scan and determined the specific activity of human (h) and canine (c) FIX variants with every amino acid substituted at position 338. Notably, we observe that hFIX-R338L is the most active variant and cFIX-R338L is sevenfold higher than wild-type (WT) cFIX. This is consistent with the previous identification of hFIX-R338L as a cause of a rare X-linked thrombophilia risk factor. Moreover, WT hFIX and cFIX are some of the least active variants. We confirmed the increased specific activity relative to FIX-WT in vivo of a new variant, cFIX-R338I, after gene therapy in an HB dog. Last, we screened 232 pediatric subjects with thromboembolic disease without identifying F9 R338 variants. Together these observations suggest a surprising evolutionary pressure to limit FIX activity with WT FIX rather than maximize FIX activity.

Intracranial hemorrhage secondary to vitamin K deficiency in X-linked myotubular myopathy.

X-linked myotubular myopathy (XLMTM) is a rare congenital myopathy characterized by profound hypotonia and poor respiratory effort at birth. The condition is associated with multiple morbidities including chronic respiratory insufficiency, feeding tube dependence, and rarely, vitamin K deficiency leading to bleeding and coagulopathy. We report a case of a 6-month-old boy with X-linked myotubular myopathy who experienced a fatal intracranial hemorrhage due to vitamin K deficiency without prior clinical evidence of cholestasis or micronutrient deficiency. We propose clinically non-apparent cholestasis in combination with acute illness and poor weight gain led to his vitamin K deficiency and intracranial hemorrhage. However, the etiology and mechanism of his cholestasis remains unclear. We conclude that children with X-linked myotubular myopathy, especially with gene therapy on the horizon, may benefit from routine hepatic, coagulation, and nutritional screening to prevent potentially catastrophic bleeding.

Combined anti-CD20 and mTOR inhibition with factor VIII for immune tolerance induction in hemophilia A patients with refractory inhibitors.

BACKGROUND: Hemophilia A (HA) inhibitor patients that fail traditional immune tolerance induction (ITI) have increased morbidity and mortality. Preclinical studies support factor VIII (FVIII) tolerance induction with a combined approach of anti-CD20 mediated transient B cell depletion and rapamycin mediated regulatory T cell (Treg) induction. METHODS: Two refractory HA inhibitor patients were treated with rituximab, rapamycin, and FVIII ITI. Their clinical course, anti-FVIII immunoglobulins, cytokines, and select lymphocytes were followed. RESULTS: One patient achieved complete and the other partial FVIII tolerance; both had marked annualized bleeding rate improvement. FVIII-specific immunoglobulins, but not total Treg counts, correlated with tolerance induction. IL-6 and IL-21 correlation with complete tolerance induction may support that down-regulation of T effectors and IgG4 production, respectively, contribute to the pathogenesis of tolerance induction. CONCLUSIONS: This regimen may be considered to induce FVIII tolerance in HA patients with refractory inhibitors. Further characterization of the FVIII-specific immune response is necessary to clarify the mechanism of immune tolerance.

Incidence of bleeding complications in pediatric patients with type 1 von Willebrand disease undergoing adenotonsillar procedures.

OBJECTIVE: To review the incidence of postoperative bleeding in children with type 1 von Willebrand disease (VWD) who were treated with a single institution protocol. STUDY DESIGN: We performed a retrospective study to determine the postoperative hemorrhage rate in pediatric patients with type 1 VWD who were treated via the Children's Hospital of Philadelphia institutional protocol. This protocol utilizes intravenous desmopressin (DDAVP), oral aminocaproic acid, and overnight observation. RESULTS: Between the years of 2000 to 2006, 41 children with type 1 VWD underwent an adenotonsillar procedure and were treated with this protocol. Seven patients (17%) experienced delayed (>24 hours after surgery) postoperative hemorrhage requiring intervention. Five of the 7 patients required cautery to control the bleeding, and the remaining 2 patients responded to DDAVP and aminocaproic acid alone. Older age and lower VW antigen levels were associated with postoperative hemorrhage (P = .05). CONCLUSIONS: Despite therapeutic intervention to decrease the risk of postoperative hemorrhage, the incidence of hemorrhage was higher in pretreated patients with type 1 VWD than in children without bleeding disorders. Further prospective studies are necessary to determine the optimal treatment to reduce bleeding complications in these patients.

The clinical management of hemophilia and head trauma: a survey of current clinical practice among pediatric hematology/oncology physicians.

BACKGROUND: Determining the appropriate evaluation for a pediatric patient with hemophilia and head trauma is a diagnostic challenge with no neuroimaging guidelines and limited clinical evidence to direct care. PROCEDURE: A questionnaire, with two case scenarios, was emailed to members of the American Society of Pediatric Hematology/Oncology. The case scenarios involved asymptomatic toddlers with severe hemophilia who had either fallen from a height (case 1) or from standing (case 2). Respondents were asked to select from six management options. The case scenarios were then altered to include: a large palpable hematoma, prophylactic factor infusion 24 hr prior, the trauma occurred 48 hr prior, wearing a soft helmet, or emesis. RESULTS: The completed response rate was 23% (252/1,077). Computed tomography (CT) was selected by 68.9% (#1) and 56.4% (#2) of respondents. In both case scenarios the presence of a palpable bruise resulted in a statistically significant increase in CT usage to 83.7% and 82.8% (P < 0.001). The use of prophylaxis did not result in a statistically significant decrease in CT usage. Duration of factor replacement was variable ranging from 1 to 4 days. CONCLUSION: Physician self reported management of pediatric patients with hemophilia and head trauma is diverse. The use of CT imaging for mild head trauma in patients without signs or symptoms of intracranial hemorrhage was very common. The use of prophylaxis did not reduce the use of head CT imaging. This variation in clinical practice demonstrates the lack of evidence regarding the management of head trauma in patients with hemophilia.

Varied opinions on thrombolysis for venous thromboembolism in infants and children: findings from a survey of pediatric hematology-oncology specialists.

BACKGROUND: Recent guidelines discourage routine use of thrombolytic agents for treatment of venous thromboembolism (VTE) in pediatric patients, but actual practice patterns are unknown. PROCEDURE: An electronic survey was emailed to all active and trainee members of the American Society of Pediatric Hematology/Oncology in April 2008. Respondents were asked a series of multiple-choice questions based on hypothetical case scenarios describing pediatric VTE, pertinent to the implementation of thrombolytic therapy and other professional demographic information. RESULTS: Two hundred eighty-five evaluable responses were obtained (22% response rate) which varied greatly with respect to all spheres of questioning. Tissue plasminogen activator (tPA) was the thrombolytic agent chosen by most respondents, but no clear consensus emerged as to appropriate indications (although preference for thrombolytic therapy increased with severity of the posed clinical scenario), mode of tPA delivery (systemic vs. catheter-directed), dose (high-dose vs. low-dose regimen) or a suitable maximum duration of therapy (range: 1-168 hr; varied according to specific dosing regimen chosen). Expertise in pediatric thrombosis, years out from fellowship training and volume of experience with cases of pediatric thrombosis were not largely associated with respondent choices; however, institutional experience with pharmacologic thrombolysis exhibited the most notable association of the professional demographic factors analyzed. CONCLUSIONS: The survey results support that clinical practice pertaining to use of thrombolytic agents in pediatric VTE varies widely but also provide useful benchmarks to aid clinical decision-making and future clinical trial design. Such varied practices stem from the lack of strong evidence supporting one therapeutic approach versus another.

Health-related quality-of-life and treatment satisfaction of individuals with hemophilia A treated with turoctocog alfa pegol (N8-GP): a new recombinant extended half-life FVIII.

BACKGROUND: Prophylactic treatment regimens lead to improvements in health-related quality-of-life (HRQoL) among individuals with hemophilia. Turoctocog alfa pegol (N8-GP) provides the benefit of extending the duration of protection from bleeding and reducing the number of injections, which is expected to impact HRQoL and treatment satisfaction (TS). AIM: To investigate the HRQoL and TS of patients with severe hemophilia A from two phase III trials evaluating the safety and efficacy of N8-GP. METHODS: HRQoL was assessed using the Haemo-QoL (reported by children and their parents) and Haem-A-QoL (reported by adults). TS was assessed using Hemo-Sat. Domain and total scores for all questionnaires ranged from 0 to 100, with lower scores indicating a better HRQoL or TS. A negative change in score indicates an improvement in HRQoL/TS. RESULTS: Mean changes in HRQoL scores were reported for 14 children aged 4-7 years, 21 children aged 8-11 years, 10 adolescents aged 13-16 years, and 163 adults (17 years and above). Mean changes in children/adolescents-reported Haemo-QoL total score were -14.0 for ages 4-7 years, -3.6 for ages 8-11 years, and -0.1 for ages 13-16 years. Mean changes in parent-reported Haemo-QoL total scores were -11.5 for 4-7 years, -8.6 for ages 8-11 years, and -4.0 for 13-16 years. Adults' mean change in Haem-A-QoL total score was -3.1 for those receiving on-demand treatment and -2.3 for those receiving prophylaxis treatment. High levels of TS with N8-GP were reported by parents of children/adolescents and the adults at the end of the trial. CONCLUSION: While most patients reported a relatively good baseline HRQoL when entering the respective trials, the HRQoL of patients was either maintained or further improved when treated with N8-GP. Adults and parents of children and adolescents reported a high level of treatment satisfaction with N8-GP.

Focusing in on use of pharmacokinetic profiles in routine hemophilia care.

BACKGROUND: Emergence of population pharmacokinetic models for prediction of individual pharmacokinetic (PK) profiles facilitates individualization of prescribed prophylactic therapy for patients with hemophilia A and B and may have a favorable impact on clinical outcomes and annual factor utilization. How providers approach the integration and application of these data into routine clinical practice is not clear. OBJECTIVE: To explore the potential application of and barriers to incorporating PK profiles into current hemophilia prophylaxis decision making. METHODS: A facilitated group discussion of hematologists practicing within the federally-supported United States Hemophilia Treatment Center Network was conducted. Separately, a group of parents of patients with severe hemophilia less than 18 years of age participated in a focus group on individualizing prophylactic factor regimens with the use of PK data. RESULTS: Physician participants constructed a conceptual model for factors that determined their selection of hemophilia prophylaxis. These factors clustered in five groupings. When charged with creating a prophylaxis regimen for a specific clinical case including PK data, eight of nine providers generated a unique regimen. Parent focus group supported PK data use as they preferred data driven treatment decisions. CONCLUSIONS: Clinician application of PK data for prophylaxis decision making is heterogeneous. Prospective evaluation of the use of PK-tailored prophylaxis in routine care and its impact on patient outcomes is needed. Parents perceived that, while obtaining blood draws could be challenging, images of factor activity decay informed their decisions about physical activity timing and provided an opportunity for partnership and shared decision making with their provider.

Headache in children with sickle cell disease: prevalence and associated factors.

OBJECTIVE: To compare the prevalence of frequent headache in children with sickle cell disease (SCD) to that of black control subjects and to assess factors associated with headache in SCD. STUDY DESIGN: In this cross-sectional study, a headache questionnaire was administered to subjects with SCD and black control subjects. Subjects answered supplementary questions about SCD complications. Clinical and radiographic information were abstracted from medical charts for subjects with SCD. RESULTS: Children (n = 241) with SCD and 141 control subjects were studied; 32.4% (95% CI 26.5%-38.7%) of subjects with SCD reported having headaches at least weekly, similar to control subjects at 27% (95% CI 19.8%-35.1%, P = NS); however, in children <13 years, headache was more common in subjects with SCD than in control subjects (24% vs 9.7%, P = .013). The prevalence of headache was similar among the different SCD genotypes. Factors associated with frequent headaches in subjects with SCD included older age, frequent vaso-occlusive pain episodes, symptoms of obstructive sleep apnea, and cerebral vessel stenosis detected by magnetic resonance angiography. CONCLUSION: The prevalence of headaches in children with SCD is similar to the general population; however, younger children with SCD report headaches more frequently than control subjects. The cause of headache is likely multifactorial, and SCD-specific factors may contribute.

Prevention of Hospital-Acquired Venous Thromboembolism in Children: A Review of Published Guidelines.

Venous thromboembolism, which includes deep venous thrombosis and pulmonary embolism, is a potentially preventable condition in children. In adults, pharmacologic prophylaxis has been shown to significantly reduce the incidence of venous thromboembolism in distinct patient cohorts. However, pediatric randomized controlled trials have failed to demonstrate the efficacy of pharmacologic prophylaxis against thrombosis associated with central venous catheters, the most important risk factor for venous thromboembolism in children. Despite the lack of supporting evidence, hospital-based initiatives are being undertaken to try to prevent venous thromboembolism in children. In this study, we sought to review the published guidelines on the prevention of venous thromboembolism in hospitalized children. We identified five guidelines, all of which were mainly targeted at adolescents and used various risk-stratification approaches. In low-risk children, ambulation was the recommended prevention strategy, while mechanical prophylaxis was recommended for children at moderate risk and pharmacologic and mechanical prophylaxis were recommended for the high-risk group. The effectiveness of these strategies has not been proven. In order to determine whether venous thromboembolism can be prevented in children, innovative clinical trial designs are needed. In the absence of these trials, guidelines can be a source of valuable information to inform our practice.

Mycoplasma pneumoniae, splenic infarct, and transient antiphospholipid antibodies: a new association?

We report 2 children with Mycoplasma pneumoniae pulmonary infection with splenic infarcts and transient antiphospholipid antibodies. This association has not been reported previously.