David F. Friedman’s research while affiliated with The Children's Hospital of Philadelphia and other places

Background Thrombocytopenia (<150,000 platelets/ul blood) is frequent among neonatal intensive care unit (NICU) patients, including 70% of extremely low birth weight infants. Severe thrombocytopenia is often treated with prophylactic transfusions of donated adult platelets in an effort to prevent bleeding. However, current transfusion practices actually increase bleeding, neurocognitive impairment, respiratory complications, and death in preterm neonates. This is likely due to physiologic differences in adult vs neonatal platelets. Thus, reducing adult platelet exposure will optimize neonatal outcomes and also conserve limited donated platelet resources. Prior clinical studies have demonstrated that 10mL/kg platelet transfusions can effectively treat thrombocytopenia. Objective We aimed to standardize 10 ml/kg prophylactic platelet transfusions in our quaternary neonatal intensive care unit (NICU) to >80% of ordered platelet transfusions in non-bleeding patients. Methods We identified 1) preconceptions about platelet safety, 2) default order sets with our electronic ordering system, and 3) cultural standards related to transfusion dosing as key drivers of current practices. Infants with procedures/surgeries within 12 hours, on anticoagulation, bleeding, or on ECMO were excluded. The primary outcome measure was compliant 10 ml/kg platelet transfusions orders. Our balancing measure were 1) repeat platelet transfusions within 36 hours and 2) frequency of major bleeding within 72 h of transfusion. Results We created a graphic dashboard based on our electronic medical record to monitor platelet ordering in real time. To define baseline practices, we tracked transfusions in the year prior to initiating our study. Our baseline compliance for 10 ml/kg platelet transfusion orders was 14%. Instead, most prophylactic transfusions were dosed at 15-20 ml/kg. Our first plan-do-study-act (PDSA) cycle targeted education through messaging at staff meetings, on NICU-wide computer screensavers, and laminated reminder cards posted at unit workstations where platelet transfusions were ordered. A second PDSA cycle reinforced platelet dosing guidelines among clinicians through newsletters and staff huddle discussions. A third PDSA cycle targeted clinical decision support within the medical record that eased ordering through defaults to recommended dosing. After consensus agreement from neonatology, cardiology, emergency medicine, oncology, and pediatric intensive care unit clinicians, we implemented electronic order set changes hospital-wide to most effectively spread practice change related to neonatal platelet transfusion dosing across all hospital units. We monitored 165 transfusions among 55 neonates (2022-2024). Following our PDSA cycle interventions, we achieved >80% dosing compliance, noting special cause variation with sustained process change that resulted in a center line shift from 14% to 88% ‘compliant’ (10 ml/kg) transfusions. There was no change in the rate of subsequent platelet transfusions within 36 hours, nor an increase in major bleeding complications within 72 hours post-transfusion. Coupled with more restrictive platelet transfusion thresholds across our network, as described in network-wide transfusion guidelines (Gilmore et al, Transfusion 2024), platelet transfusions dropped by 44% in the first 6 months after electronic order changes (p<0.05 by two tailed t test). Conclusion A standardized prophylactic platelet transfusion dose of 10mL/kg was established through hospital-wide collaborative efforts. We used clinician education and electronic medical record technologies to improve platelet transfusion practices within our NICU, reducing platelet exposures that have been linked with adverse outcomes in preterm neonates. Standardized 10ml/kg platelet transfusion dosing will optimize safety and efficacy of neonatal platelet transfusions and conserve limited donated platelet supplies in line with current literature.

Background:Automated red cell exchange (RCE) is recommended for patients with sickle cell disease (SCD) requiring chronic red blood cell (RBC) therapy. However, the high RBC requirements of RCE present challenges related to scarcity of matched RBC units and increased risk of alloimmunization. In isovolemic hemodilution RCE (IHD), a red cell depletion with normal saline or 5% albumin replacement occurs prior to RCE. The intent of IHD is to decrease the number of RBC units needed to attain the target hemoglobin S (HbS)%. However, the real-world effect of IHD on RBC usage is unclear, and less than half of recently surveyed institutions use IHD (Karafin et al, 2020). Thus, we conducted a retrospective cohort study to compare RBC usage in patients with SCD receiving standard vs. IHD RCE. Methods:Patients with SCD-SS at our institution undergoing a period of chronic standard RCE followed by chronic IHD RCE between 2003-2022 were identified. Periods of at least 6 consecutive procedures of the same RCE type (standard vs. IHD) with ≤ 45 days between procedures were labeled as RCE “clusters”. Subjects were included if they had at least one standard cluster concluding within 1 year of the start of an IHD cluster, with a consistent HbS goal across all procedures. Cluster duration was trimmed to achieve two clusters (one IHD, one standard) of equal duration per subject. Subject and RCE characteristics in IHD vs. standard RCE were described with paired t-tests. To account for repeat measures per subject, linear mixed effects regression models were used for multivariate analyses. Primary outcomes were RBC units per RCE and annualized cumulative RBC units per cluster. Baseline covariates, including year, age, sex, and HbS goal, were assessed at the index RCE procedure for inclusion in the multivariate model. Baseline hematocrit, baseline total blood volume (TBV), change in TBV between clusters, and cluster duration (for annualized analysis) were assessed as both covariates and interaction terms. Postestimation pairwise comparisons were used to model IHD effects at different TBV values. Results:Our final analysis included 40 patients with 1213 RCE procedures. Median baseline age was 12.5 (range 7-29) years, 55% of subjects were male, and 85% had a HbS goal of <30%. Median cluster duration was 9.2 (range 3.3-35.7) months, with a median of 12 transfusions per cluster and 3 RBC units per RCE (range 2-10). In paired analyses, baseline TBV was significantly larger in IHD clusters vs. standard (3240 mL vs 2851 mL, p<0.001), as was baseline hematocrit (28.3% vs 26.4%, p<0.001). Mean inter-procedure interval was 25 days in both clusters. Target fraction of cells remaining (FCR), representing the proportion of subject RBCs remaining after RCE, was lower in the IHD clusters (38.3% vs. 45.0%, p<0.001). RBC units/mL TBV did not differ between cluster categories, with 0.0012 RBC units/mL in both groups. In RCEs with HbS goal < 30%, mean pre-RCE HbS was 29.9% in IHD vs. 30.9% in standard clusters. This difference was not statistically significant (p = 0.22). Our multivariate mixed effects model included HbS goal, hematocrit, year, and TBV, with interactions between RCE type and both baseline TBV and TBV change between clusters. Results were modeled to simulate no TBV change between clusters. TBV modified the effect of IHD on RBC units per procedure; partial unit savings with IHD were predicted in patients with a larger TBV.In individuals with TBV values < 3900 mL (at baseline), units per procedure did not differ between standard and IHD clusters. However, in those with TBV ≥ 3900mL, IHD conferred a statistically significant but small RBC unit savings that increased with larger TBVs. The peak saving with the largest TBV in our sample, 5055 mL, was 0.78 units/procedure (95% CI: 0.1 - 1.5 units saved, p =0.026). IHD was not associated with a significant change in annualized RBC unit exposure. However, there was a similar trend towards RBC unit savings with increasing TBV, with a predicted 5.69 units/yr saved with IHD at a TBV of 5055 mL (95% CI: 18.2 units saved to 6.8 units gained, p = 0.373). Discussion:Our study suggests that IHD has limited utility in patients with small TBV receiving chronic red cell exchange. In patients with a lower TBV, IHD did not result in meaningful savings of RBC units. Conversely, larger patients may benefit from IHD. Prospective, multi-center studies are needed to standardize approaches to RCE and identify appropriate IHD candidates.

Anti-D can occur in D-positive patients who inherit RHD genetic variants encoding partial D antigen expression, but unexpected anti-D is also found in the plasma of patients with sickle cell disease who have conventional RHD gene(s) and are transfused with units from Black donors. These anti-D are likely stimulated by variant Rh expressed on donor cells, however patients with anti-D, regardless of cause, are transfused for a lifetime with D-negative (Rh-negative) blood. This results in significant increased use of Rh-negative units, especially for those requiring chronic transfusion, which can strain Rh-negative blood inventories. We tested whether D-positive patients who made anti-D and had conventional RhD by RHD genotyping could safely be returned to D-positive transfusions without anti-D reappearance or compromised RBC survival using RHD genotype-matched units from Black donors. Five patients receiving chronic red cell exchange received an increasing number of D-positive units per procedure with a total of 72 D-positive RHD genotyped units transfused, with no anti-D restimulation. Unexpected anti-C and anti-E were identified during the study associated with donors with variant RHCE alleles. RH genotyping of D-positive units for transfusion may improve use and allocation of valuable Black donor units and reduce demand for Rh-negative blood.

This extraordinary case showcases the identification of a rare anti-En a specificity that was assisted by DNA-based red blood cell antigen typing and collaboration between the hospital blood bank in the United States, the home blood center in Qatar, the blood center Immunohematology Reference Laboratory, as well as the American Rare Donor Program (ARDP) and the International Society for Blood Transfusion (ISBT) International Rare Donor Panel. En a is a high-prevalence antigen, and blood samples from over 200 individuals of the extended family in Qatar were crossmatched against the patient’s plasma with one compatible En(a–) individual identified. The ISBT International Rare Donor Panel identified an additional donor in Canada, resulting in a total of two En(a–) individuals available to donate blood for the patient.

Background Red cell alloimmunization remains a challenge for individuals with sickle cell disease (SCD) and contributes to increased risk of hemolytic transfusion reactions and associated comorbidities. Despite prophylactic serological matching for ABO, Rh, and K, red cell alloimmunization persists, in part, due to a high frequency of variant RH alleles in patients with SCD and Black blood donors. Study Design and Methods We compared RH genotypes and rates of alloimmunization in 342 pediatric and young adult patients with SCD on chronic transfusion therapy exposed to >90,000 red cell units at five sites across the USA. Genotyping was performed with RHD and RHCE BeadChip arrays and targeted assays. Results Prevalence of overall and Rh‐specific alloimmunization varied among institutions, ranging from 5% to 41% ( p = .0035) and 5%–33% ( p = .0002), respectively. RH genotyping demonstrated that 33% RHD and 57% RHCE alleles were variant in this cohort. Patients with RHCE alleles encoding partial e antigens had higher rates of anti‐e identified than those encoding at least one conventional e antigen ( p = .0007). There was no difference in anti‐D, anti‐C, or anti‐E formation among patients with predicted partial or altered antigen expression compared to those with conventional antigens, suggesting that variant Rh on donor cells may also stimulate alloimmunization to these antigens. Discussion These results highlight variability in alloimmunization rates and suggest that a molecular approach to Rh antigen matching may be necessary for optimal prevention of alloimmunization given the high prevalence of variant RH alleles among both patients and Black donors.

Previous research suggests that individuals with 22q11.2 deletion syndrome (DS) have an increased risk of bleeding following cardiac surgery. However, current guidelines for management of patients with 22q11.2DS do not provide specific recommendations for perioperative management. This study sought to identify specific risk factors for bleeding in this patient population. Examine the factors determining bleeding and transfusion requirements in patients with 22q11.2DS undergoing cardiac surgery. This was a single center review of patients who underwent cardiac surgery at the Children’s Hospital of Philadelphia from 2000 to 2016. Data was extracted from the medical record. Frequency of bleeding events, laboratory values, and transfusion requirements were compared. We included 226 patients with 22q11.2DS and 506 controls. Bleeding events were identified in 13 patients with 22q11.2DS (5.8%) and 27 controls (5.3%). Platelet counts were lower among patients with 22q11.2DS than in control patients, but not statistically different comparing bleeding to not bleeding. Patients with 22q11.2DS received more transfusions (regardless of bleeding status). However, multivariate analysis showed only procedure type was associated with increased risk of bleeding (p = .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.

Introduction Most red blood cell (RBC) alloimmunization in sickle cell disease (SCD) is caused by sensitization to Rh (D, C, c, E, and e) and K antigens. Provision of serologic Rh and K-matched RBCs has reduced but not eliminated Rh alloantibody formation due to the high genetic variation within the RH loci in Blacks. Over 85% of patients with SCD, as well as Black donors needed to support CEK matching programs, have variant RHD or RHCE alleles that result in loss or alteration of Rh antigens. These variant Rh proteins are not detected by standard serologic tests, and thus, genetically matched RBCs may be necessary to prevent all Rh alloimmunization events. We previously used bioinformatic modeling to show that RH genetic matching was achievable for a cohort of ~200 patients of whom ~50% were chronically transfused, and represented 98 different RHD/RHCE allele combinations, with only 10 additional donations each weekday (~1050 Black donors/month) than required for serologic Rh and K matching. The real-world feasibility of providing RH genotype-matched RBCs to patients requiring regular transfusion has not been tested. Methods We performed a pilot study to evaluate the feasibility of providing RH genotype-matched RBCs from Black and Hispanic donors to non-Rh- and Rh-alloimmunized chronically transfused patients with SCD (1 to 18 years old). Black donor units at the blood center were first screened by serology, HEA BeadChip, and in-house RH SNP assays, and those selected for transfusion to study subjects had comprehensive RHD and RHCE genotyping. Data captured included RH genotypes of matched units identified, transfusion delays, unit age at time of transfusion, and pre-transfusion hemoglobin (Hb) and HbS levels. On-study values were compared to pre-study values obtained in the 6 to 12 transfusion visits prior to study enrollment. Results The study opened in February 2020. Due to the COVID-19 pandemic, donor center collections dropped to a nadir of ~500 Black donor units/month in 2020 but returned to ~1500 units/month currently, similar to pre-COVID numbers. For 14 participants (13 Black, 1 Hispanic), we transfused 327 RH genotype-matched units; 287 (88%) were exact RH genotype-matched (donor with identical genotype, homozygous for a matching RH haplotype, or RH allele match) and 40 (12%) were RH matched with the provision that RHD*RHD and *DAU0 and RHCE*ce and *ce48C are equivalent since no epitopes appear to differ between these alleles. No transfusion visits (n=183) were postponed due to the inability to identify RH genotype-matched units, including during the pandemic and national blood shortages that had a disproportionate impact on Black donations. Using individual patients as factors, ANOVA showed no statistically significant difference in unit age (days, Figure) or pre-transfusion Hb values between pre- and on-study transfusion visits. Although the goal maintenance pre-transfusion HbS levels varied between 30 and 50%, a statistically significant lower mean HbS on- (n=183) vs pre-study (n=139) (ANOVA F-ratio 15.4, p=0.000) (Figure) potentially suggests improved transfused RBC survival with RH genotype matching. This feasibility trial was not powered to detect a difference in alloantibody formation, but no Rh nor non-Rh antibody have been detected. Conclusion Recruitment of minority blood donors is a growing initiative nationally needed to support CEK matching. Our preliminary results suggest that genetic RBC matching at the RH loci may be feasible with Black and Hispanic donors. Donor center RH genotyping can facilitate transfusion of RH genotype-matched RBCs, improve allocation of minority and rare donor units and, at the same time, potentially improve patient care by avoiding Rh alloimmunization for individuals with SCD.

RH diversity among patients and donors contributes to Rh immunization despite serologic Rh‐matched red cell transfusions. Anti‐D can occur in D+ patients with RHD variants that encode partial D antigens. Anti‐D has also been reported in patients with conventional RHD transfused primarily with units from Black donors who frequently have variant RHD. We report 48 anti‐D in 690 D+ transfused individuals with sickle cell disease, categorized here as expressing conventional D, partial D or D antigen encoded by RHD*DAU0. Anti‐D formed in a greater proportion of individuals with partial D, occurred after fewer D+ unit exposures, and remained detectable for longer than for those in the other categories. Among all anti‐D, 13 had clinical or laboratory evidence of poor transfused red cell survival. Most individuals with anti‐D were chronically transfused, including 32 with conventional RHD who required an average of 62 D− units/year following anti‐D. Our findings suggest that patients with partial D may benefit from prophylactic D− or RH genotype‐matched transfusions to prevent anti‐D. Future studies should investigate whether RH genotype‐matched transfusions can improve use of valuable donations from Black donors, reduce D immunization and minimize transfusion of D− units to D+ individuals with conventional RHD or DAU0 alleles.

The COVID-19 pandemic has created major disruptions in health care delivery, including a severe blood shortage. The inventory of Rh and K antigen–negative red cell units recommended for patients with hemoglobinopathies became alarmingly low and continues to be strained. Because patients with sickle cell disease requiring chronic red cell exchange (RCE) incur a large demand for red cell units, we hypothesized that implementation of 2 measures could reduce blood use. First, obtaining the pretransfusion hemoglobin S (HbS) results by procedure start time would facilitate calculation of exact red cell volume needed to achieve the desired post-RCE HbS. Second, as a short-term conservation method, we identified patients for whom increasing the targeted end procedure hematocrit up to 5 percentage points higher than the pretransfusion level (no higher than 36%) was not medically contraindicated. The goal was to enhance suppression of endogenous erythropoiesis and thereby reduce the red cell unit number needed to maintain the same target HbS%. These 2 measures resulted in an 18% reduction of red cell units transfused to 50 patients undergoing chronic RCE during the first 6 months of the COVID-19 pandemic. Despite reduction of blood use, pretransfusion HbS% target goals were maintained and net iron accumulation was low. Both strategies can help alleviate a shortage of Rh and K antigen–negative red cells, and, more generally, transfusing red cell units based on precise red cell volume required can optimize patient care and judicious use of blood resources.

Chronically transfused patients with thalassemia are at risk for red cell alloimmunization. No studies have specifically examined alloimmunization after implementation of prophylactic Rh (D, C, E) and K matched red cells in a racially diverse population of thalassemia patients and donors. This retrospective study examined Rh antibodies among 40 chronically transfused patients (Asian, White, Black, Indian, Middle Eastern) with thalassemia receiving a mean of 174 serologic prophylactic RhD, C, E, and K matched red cell units. We examined the patients’ RH genotype, as well as donor race and Rh phenotypes over 3 transfusion events preceding antibody detection. Eighteen alloantibodies were detected in 13 of 40 patients (32.5%), with an alloimmunization rate of 0.26 antibodies per 100 units transfused. Thirteen antibodies (72.2%) were directed against Rh (5 anti-D, 4 anti-C, 2 anti-E, 1 anti-e, 1 anti-V), despite donor phenotypes that confirmed lack of transfusion of D, C, or E antigens to patients lacking the corresponding antigen(s). Ten of 40 patients had an altered RH genotype, but the Rh antibodies were not associated with patients with variant RH. Black donors with a known high frequency of RH variants provided 63% of the units transfused in the 3 visits preceding unexplained anti-Rh detection. Rh alloimmunization not explained by the thalassemia patients’ RH genotype or the donors’ serologic phenotype suggests more precise matching is needed, and the role of donor RH genotypes on alloimmunization should be explored. Extending Rh D, C, and E matching to include c and e would result in better-matched units and further minimize Rh alloimmunization.