About

Char M. Witmer, MD, MSCE, is a Clinical Associate Professor of Pediatrics specializing in Hematology at the Children's Hospital of Philadelphia. He is a consulting hematologist and staff physician in the Division of Hematology at the hospital. Dr. Witmer's clinical expertise focuses on pediatric hematology with an emphasis on hemostatic and thrombotic disorders. He holds a Bachelor of Arts in Biology and American Sign Language and Linguistics from the University of Rochester, obtained in 1996, and earned his Medical Degree from the University of Rochester School of Medicine in 2000. Furthering his specialization, he completed a Clinical Research Certificate Program at the University of Pennsylvania Center for Clinical Epidemiology and Biostatistics in 2005, and a Master of Science in Clinical Epidemiology from the same institution in 2011. Additionally, he has obtained multiple certifications, including in clinical quality improvement, EPIC physician building, and physician leadership. Dr. Witmer serves as the Assistant Director of the Comprehensive Hemostasis and Thrombosis Program, Medical Director of the 5WA Hematology Inpatient Unit, and Associate Program Director for the Pediatric Hematology Oncology Fellowship Program at Children's Hospital of Philadelphia. His research expertise is centered on pediatric hemostasis and thrombosis, contributing to the understanding and management of blood disorders in children.

Research topics

• Medicine
• Pediatrics
• Internal medicine
• Intensive care medicine
• Surgery

Selected publications

• Management of severe acute pulmonary haemorrhage in children

  The Lancet Child & Adolescent Health · 2025-04-15 · 5 citations

  reviewOpen access
  PublisherOA PDFDOI

• Description of a national, multi‐center registry of patients with sickle cell disease and SARS‐CoV‐2 infection: Data from the Pediatric COVID‐19 United States Registry

  Pediatric Blood & Cancer · 2024-03-12

  articleOpen access

  Children with sickle cell disease (SCD) are at risk of complications from viral infections, including SARS-CoV-2. We present the clinical characteristics and outcomes of pediatric patients with SCD from the Pediatric COVID-19 United States Registry who developed acute COVID-19 due to SARS-CoV-2 infection (n = 259) or multisystem inflammatory syndrome in children (MIS-C; n = 4). Nearly half of hospitalized children with SCD and SARS-CoV-2 infection required supplemental oxygen, though children with SCD had fewer intensive care (ICU) admissions compared to the general pediatric and immunocompromised populations. All registry patients with both SCD and MIS-C required ICU admission. Children with SCD are at risk of severe disease with SARS-CoV-2 infection, highlighting the importance of vaccination in this vulnerable population.

  PublisherOA PDFDOI

• Innovative Model for Creation and Use of Co-Developed Pain Management Plans for Patients with Sickle Cell Disease

  Blood · 2024-11-05

  article

  Background: Sickle cell disease (SCD) is an inherited blood disorder characterized by chronic hemolytic anemia, severe debilitating pain, and health disparities. The ASH Research Collaborative launched a SCD Learning Community (LC) to aid in the improvement of clinical practice and patient outcomes, and designated improving the reliable use of co-developed pain plans as a priority for LC pilot sites. Pain management plans can provide individuals with SCD and their medical team with guidance to enable timely interventions to relieve suffering more quickly and potentially decrease emergency department (ED) visits and admissions. At the outset of this initiative as an LC pilot site, 0% of SCD patients at our institution had formal pain management plans. Clinical pathways to guide ED care were not individualized and focused on opioid management. Patients and families expressed strong interest in integrative health (IH) and nonpharmacologic approaches to pain management. Therefore, we postulated that co-development of pain plans would empower individuals with SCD to be more engaged in treatment decisions with greater patient and family satisfaction. Objectives: Aim 1 was to increase the number of patients aged 2-20 years with severe genotypes (HbSS/Sß0Thalassemia), inclusive of payor or socioeconomic status, who have co-developed pain management plans from 0% to 70% by 10/30/2023 (pilot phase). Aim 2 was to expand use of an electronic health record (EHR)-based co-developed pain plan across all providers and all genotypes for at least 50% of the population by 6/30/2024. Methods: A multidisciplinary collaboration, including quality improvement (QI), hematology, ED and IH staff, created a key driver diagram, process map and pain plan template with real-time provider and patient feedback. Materials from other LC pilot sites and relevant institutional QI initiatives were reviewed. Using the Epic EHR and Healthy Planet population health platform (Epic Systems Corporation; Verona, WI), eligible patients for the pilot phase were identified, filtering for age, SCD genotype, and ≥1 narcotic prescription for pain in the past year. Pain plans were completed initially on paper during routine outpatient visits, refined based on feedback and translated into an electronic smart form and patient-facing pain plan accessible in MyChart. A 3-item REDCap survey was completed by caregivers to assess engagement and satisfaction with the plan. The Child Opportunity Index (COI), a composite measure of economic, educational, health and safety factors in neighborhoods, and payor status were evaluated to assess equity and inclusion in this initiative. Results: ~950 children and young adults with SCD receive care at this urban, academic medical center. The state-normed COI was Very Low to Low for 74% of patients in the active SCD cohort within our Healthy Planet registry. About 70% have a governmental primary medical payor; 88% self-identify as non-Hispanic Black; and 97% indicate English as their preferred language. 46 patients met pilot phase eligibility criteria. 35 pain plans (76.1%) were completed by 10/30/2023. 35 feedback surveys (100%) were completed and demonstrated high engagement and satisfaction among SCD families. 92% of respondents felt the pain plan was co-developed and 89% said they were very likely to use it. Epic-based pain plans covering outpatient and ED management were integrated into clinical workflows. QR codes for IH informational videos for non-pharmacologic approaches to wellness and pain management were added to the after-visit summary. As of 07/25/2024, 372 patients (50% of target population) have pain plans. Their individualized preferences are now automatically displayed for prescribing providers when the ED SCD pain orderset is accessed. There were no differences in COI, payor status, or race/ethnicity between those who do or do not have pain plans. Conclusion: Co-developed pain management plans should facilitate more effective SCD treatment and improve the patient/family experience using an approach that is feasible, sustainable, and scalable. Creation of pain plans for more SCD patients is ongoing. Current priorities include completion of an inpatient component and development of a QI-metric dashboard to track pain plan use and impact of pain plans on acute care utilization. Planned outcome measures include ED use, time to first opioid in ED, and hospital admission rates.

  PublisherDOI

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

  JACC Advances · 2024-03-19 · 10 citations

  articleOpen access

  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. 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. 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. Of 3,136 subjects, 70% were at least 12 years of age, and 46% were male. Sixty-two percent had at least one 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. 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.

  PublisherDOI

• Insights and Characteristics of Pediatric Central Venous Catheter Malfunction and Catheter-Associated Deep Vein Thrombosis: A Subanalysis of the Circle Study

  Blood · 2024-11-05

  article

  Introduction: Central venous catheters (CVCs) are increasingly placed in children for administration of medications, fluids, parenteral nutrition as well as frequent blood collection. CVC type or insertion technique, underlying medical conditions and type of infused medications can impact CVC function and longevity. CVC malfunction is known to be associated with deep vein thrombosis (DVT). Our previous study of children with CVCs (Jaffray, et al, Blood 2020), found those with a CVC malfunction were six times more likely to develop a DVT. The aim of this subanalysis was to evaluate risk factors for CVC malfunction and subsequently the development of a DVT in children with peripherally inserted central catheters (PICCs) and tunneled lines (TLs) within our Clot Incidence Rates in Central Lines (CIRCLE) study. Methods: This is a subanalysis of the multicenter, prospective CIRCLE study conducted from October 2013 to June 208. Randomly selected children aged 6 months to <18 years of age with newly placed PICCs or TLs were enrolled and monitored until CVC removal or end of the study period. A CVC malfunction was defined as any CVC that required tissue plasminogen activator (t-PA) or had malfunction reported as ‘blockage’ or ‘mechanical’. CVC related risk factors for DVT included type, size, material, length, number of lumens of CVC and insertion technique including number of insertion attempts, placement via ultrasound guidance and whether CVC was placed by an interventional radiology (IR) technique. Patient related factors included age, medical history, vein accessed, location of CVC tip, having a catheter associated blood stream infection (CLABSI), receiving total parental nutrition or anticoagulation (other than routine heparin flushes). DVT was confirmed on radiologic examination of those subjects with symptoms of CVC-associated DVT. To examine associations between risk factors and CVC malfunction, we performed survival analysis by fitting univariate and multivariate Weibull regression models. From these models, we obtained hazard ratios (HR) and their respective 95% confidence intervals (CI). Results: A total of 1951 CVCs were included in this analysis. There were 380 (19.5%) CVCs with at least one malfunction. Median [interquartile range (IQR)] time from CVC insertion to the first malfunction was 20 [7.75-57] days. The majority of CVCs with malfunction had one episode (n= 219, 57.6%), followed by two malfunctions (n= 75, 19.7%) and 22.7%(n=86) had three or more malfunctions. There was a significantly higher rate of malfunction in PICCs as compared to TLs (HR=2.14, 95% CI:1.71-2.68, p value<0.0001). On multivariable analysis, risk factors associated with an increased risk of malfunction included previous CVC (HR=1.5, 95% CI:1.2-1.9, p=0.002), CVC size < 4 French (HR=3.23, 95% CI:2.51-4.17, p<0.0001), having two or more catheter lumens (HR=2.9, 95% CI:2.3-3.6, p<0.0001) and more than two insertion attempts (HR=2.2, 95% CI:1.4-3.5, p=0.0005). CVCs placed by IR (HR=0.4, 95% CI:0.3-0.5, p<0.0001) and the presence of a CLABSI (HR=0.6, 95% CI:0.4-0.9, p=0.009) were associated with significantly lower risk of CVC malfunction. DVT was diagnosed in 22 (5.8%) CVCs with a malfunction and the median (IQR) time to diagnosis of DVT after CVC malfunction was 6 (1-18.5) days. The HR of DVT development for those requiring one t-PA dose versus those receiving no t-PA was 0.87 (95% CI:0.16-4.57, p= 0.87), compared to a HR of 1.23 (95% CI:0.21-7.23, p= 0.81) for two doses, 1.15 for three doses (95% CI:0.15-8.68, p=0.89) and 3.37 for four or more doses (95% CI:0.66-17.27, p=0.11) of t-PA. Conclusion: Our previous study identified that CVCs with malfunction were more likely to develop a DVT. PICCs had nearly a 9-fold increased risk of DVT as compared to TLs. In this sub-analysis, nearly one fifth of CVCs placed in children had a malfunction. Malfunction risk factors included a previous CVC, smaller lumen size, multi-lumen CVCs, multiple insertion attempts and CVCs not being inserted by IR technique. Interestingly, the presence of a CLABSI was associated with lower rates of CVC malfunction which could be attributed to frequent CVC access that maintains patency or use of medication locks for CLABSI. Although not statistically significant, likely due to small numbers, CVC-associated DVT seems to increase with multiple doses of t-PA which should raise suspicion to screen for DVT if a CVC requires repeated t-PA instillation.

  PublisherDOI

• Sports participation in chronic immune thrombocytopenia: Safer than you thought?

  Pediatric Blood & Cancer · 2023-09-20 · 1 citations

  article1st authorCorresponding

  BACKGROUND/OBJECTIVES: Pediatric patients with chronic immune thrombocytopenia (ITP) commonly have activity limitations placed to prevent injury without data guiding clinical decision-making. The objective of this study was to determine risk factors associated with injury in children with chronic ITP. DESIGN/METHODS: Retrospective single-center cohort study from January 1, 2008 to March 31, 2019 in subjects age 5-21 years with chronic ITP (platelet count < 100,000/µL for >1 year). RESULTS: One-hundred-two subjects were included, with a mean diagnosis age of 9.3 ± 4.6 years. Mean follow-up 3.8 ± 2.3 years; 61% (62) of subjects were female; 60% (61) participated in organized sports, mean 2 ± 1 sports/subject; 8.8% (9) received ITP therapy for sports participation. Common sports: basketball (28%) and soccer (28%). There were 31 injuries in 26 subjects, and 68% (21) occurred while at play. Most common injuries: 68% (21/31) soft tissue and 23% (7/31) head trauma. Fifteen (48%) injuries were severe enough for medical evaluation at the time of injury. Only one patient received acute ITP treatment for their injury. Injury was associated with participation in high-risk sports (p < .001), male sex (p = .007), and participation in multiple organized sports (p = .008). CONCLUSION: In this study of 102 pediatric subjects with chronic ITP, injury was mild and infrequent predominantly occurring while at play. The majority participated in organized sports safely. Risk of injury was associated with high-risk sport participation (p < .001). Only one injury necessitated ITP treatment, suggesting that participation in most sports is likely safe in children with chronic ITP.

  PublisherDOI

• A case-control study of bleeding risk in children with 22q11.2 deletion syndrome undergoing cardiac surgery

  Platelets · 2023-12-15 · 4 citations

  articleOpen access

  = .012). The overall risk of bleeding when undergoing cardiac surgery is not different in patients with 22q11.2DS compared to non-deleted patients. Though platelet counts were lower in patients with 22q11.2DS, only procedure type was significantly associated with an increased risk of bleeding.

  PublisherDOI

• SC4_4. Pathways to pre-eclampsia: learning from lived experience about the risk factors for pre-eclampsia

  Pregnancy Hypertension · 2023-09-01

  article
  PublisherDOI

• Outcomes in infants with unprovoked venous thromboembolism: A retrospective cohort study

  Research and Practice in Thrombosis and Haemostasis · 2023-05-01 · 1 citations

  articleOpen access

  Background: Although children aged <1 year have a relatively high rate of venous thromboembolism (VTE) compared to older children, most have additional prothrombotic risk factors.Unprovoked VTE is rare, and little is known about this population, particularly the risk of recurrent VTE. Objectives:We aimed to determine the rate of recurrent VTE in infants with prior unprovoked VTE and evaluate long-term, end-organ outcomes for infants with renal and intracranial vein thrombosis.Methods: Infants <1 year of age with an unprovoked VTE between 2003 and 2021 at a single institution were included.Time to recurrent event and anticoagulation duration were summarized using the Kaplan-Meier estimator.Neurologic outcomes were summarized with the pediatric stroke outcome measure for infants with cerebral sinovenous, medullary, or cortical vein thrombosis.Kidney outcomes were summarized with estimated glomerular filtration rates for infants with renal vein thrombosis.Anticoagulation was summarized.Results: Forty infants with intracranial, renal, portal, and extremity VTE met the inclusion criteria and were followed for a median of 4.7 years (IQR, 2.1-8.5).Most VTE events occurred during the first month of life.There was 1 recurrent event in 237 person-years of follow-up (incidence rate, 4 per 1000 [95% CI, 0.6-29.9]person-years).In outpatient follow-up, 40% of infants with intracranial thrombosis met criteria for moderate or severe neurologic outcomes and two-thirds of infants with a prior renal vein thrombosis had abnormal kidney function (estimated glomerular filtration rate < 90 mL/min/1.73m 2 ). Conclusion:There is a low rate of recurrent VTE but significant end-organ morbidity in infants with unprovoked VTE.

  PublisherOA PDFDOI

• High rate of recurrent venous thromboembolism in children and adolescents with unprovoked venous thromboembolism

  Journal of Thrombosis and Haemostasis · 2023-01-01 · 16 citations

  articleOpen access
  PublisherOA PDFDOI

Recent grants

• VWF Multimer Distribution a Phenotypic Modifier of Hemophilia A

  NIH · $504k · 2011–2014

Frequent coauthors

• Leslie Raffini

  Children's Hospital of Philadelphia

  86 shared

• Therese M. Giglia

  Children's Hospital of Philadelphia

  66 shared

• Jonathan W. Byrnes

  University of Alabama at Birmingham

  49 shared

• David Procaccini

  Johns Hopkins Hospital

  49 shared

• Margaret V. Ragni

  University of Pittsburgh

  47 shared

• Roshni Kulkarni

  Michigan State University

  47 shared

• Lynn Malec

  40 shared

• Peter A. Kouides

  Rochester General Hospital

  39 shared