Consensus modeling: Safer transfer learning for small health systems.

Predictive modeling is becoming an essential tool for clinical decision support, but health systems with smaller sample sizes may construct suboptimal or overly specific models. Models become over-specific when beside true physiological effects, they also incorporate potentially volatile site-specific artifacts. These artifacts can change suddenly and can render the model unsafe. To obtain safer models, health systems with inadequate sample sizes may adopt one of the following options. First, they can use a generic model, such as one purchased from a vendor, but often such a model is not sufficiently specific to the patient population and is thus suboptimal. Second, they can participate in a research network. Paradoxically though, sites with smaller datasets contribute correspondingly less to the joint model, again rendering the final model suboptimal. Lastly, they can use transfer learning, starting from a model trained on a large data set and updating this model to the local population. This strategy can also result in a model that is over-specific. In this paper we present the consensus modeling paradigm, which uses the help of a large site (source) to reach a consensus model at the small site (target). We evaluate the approach on predicting postoperative complications at two health systems with 9,044 and 38,045 patients (rare outcomes at about 1% positive rate), and conduct a simulation study to understand the performance of consensus modeling relative to the other three approaches as a function of the available training sample size at the target site. We found that consensus modeling exhibited the least over-specificity at either the source or target site and achieved the highest combined predictive performance.

Preoperative Anemia and Postoperative Outcomes in Cardiac Surgery: A Mediation Analysis Evaluating Intraoperative Transfusion Exposures.

BACKGROUND: Preoperative anemia is associated with adverse outcomes in cardiac surgery, yet it remains unclear what proportion of this association is mediated through red blood cell (RBC) transfusions. METHODS: This is a historical observational cohort study of adults undergoing coronary artery bypass grafting or valve surgery on cardiopulmonary bypass at an academic medical center between May 1, 2008, and May 1, 2018. A mediation analysis framework was used to evaluate the associations between preoperative anemia and postoperative outcomes, including a primary outcome of acute kidney injury (AKI). Intraoperative RBC transfusions were evaluated as mediators of preoperative anemia and outcome relationships. The estimated total effect, average direct effect of preoperative anemia, and percent of the total effect mediated through transfusions are presented with 95% confidence intervals and P -values. RESULTS: A total of 4117 patients were included, including 1234 (30%) with preoperative anemia. Overall, 437 of 4117 (11%) patients went on to develop AKI, with a greater proportion of patients having preoperative anemia (219 of 1234 [18%] vs 218 of 2883 [8%]). In multivariable analyses, the presence of preoperative anemia was associated with increased postoperative AKI (6.4% [4.2%-8.7%] absolute difference in percent with AKI, P < .001), with incremental decreases in preoperative hemoglobin concentrations displaying greater AKI risk (eg, 11.9% [6.9%-17.5%] absolute increase in probability of AKI for preoperative hemoglobin of 9 g/dL compared to a reference of 14 g/dL, P < .001). The association between preoperative anemia and postoperative AKI was primarily due to direct effects of preoperative anemia (5.9% [3.6%-8.3%] absolute difference, P < .001) rather than mediated through intraoperative RBC transfusions (7.5% [-4.3% to 21.1%] of the total effect mediated by transfusions, P = .220). Preoperative anemia was also associated with longer hospital durations (1.07 [1.05-1.10] ratio of geometric mean length of stay, P < .001). Of this total effect, 38% (22%, 62%; P < .001) was estimated to be mediated through subsequent intraoperative RBC transfusion. Preoperative anemia was not associated with reoperation or vascular complications. CONCLUSIONS: Preoperative anemia was associated with higher odds of AKI and longer hospitalizations in cardiac surgery. The attributable effects of anemia and transfusion on postoperative complications are likely to differ across outcomes. Future studies are necessary to further evaluate mechanisms of anemia-associated postoperative organ injury and treatment strategies.

Transfusion targets and adverse events in pediatric perioperative acute Anemia.

STUDY OBJECTIVE: To evaluate the association between pretransfusion and posttransfusion hemoglobin concentrations and the outcomes of children undergoing noncardiac surgery. DESIGN: Retrospective review of patient records. We focused on initial postoperative hemoglobin concentrations, which may provide a more useful representation of transfusion adequacy than pretransfusion hemoglobin triggers (the latter often cannot be obtained during acute surgical hemorrhage). SETTING: Single-center, observational cohort study. PATIENTS: We evaluated all pediatric patients undergoing noncardiac surgery who received intraoperative red blood cell transfusions from January 1, 2008, through December 31, 2018. INTERVENTIONS: None. MEASUREMENTS: Associations between pre- and posttransfusion hemoglobin concentrations (g/dL), hospital-free days, intensive care unit admission, postoperative mechanical ventilation, and infectious complications were evaluated with multivariable regression modeling. MAIN RESULTS: In total, 113,713 unique noncardiac surgical procedures in pediatric patients were evaluated, and 741 procedures met inclusion criteria (median [range] age, 7 [1-14] years). Four hundred ninety-eight patients (68%) with a known preoperative hemoglobin level had anemia; of these, 14% had a preexisting diagnosis of anemia in their health record. Median (IQR) pretransfusion hemoglobin concentration was 8.1 (7.4-9.2) g/dL and median (IQR) initial postoperative hemoglobin concentration was 10.4 (9.3-11.6) g/dL. Each decrease of 1 g/dL in the initial postoperative hemoglobin concentration was associated with increased odds of transfusion within the first 24 postoperative hours (odds ratio [95% CI], 1.62 [1.37-1.93]; P < .001). No significant relationships were observed between postoperative hemoglobin concentrations and hospital-free days (P = .56), intensive care unit admission (P = .71), postoperative mechanical ventilation (P = .63), or infectious complications (P = .74). CONCLUSIONS: In transfused patients, there was no association between postoperative hemoglobin values and clinical outcomes, except the need for subsequent transfusion. Most transfused patients presented to the operating room with anemia, which suggests a potential opportunity for perioperative optimization of health before surgery.

Postoperative Transfusions after Administration of Delayed Cold-stored Platelets versus Room Temperature Platelets in Cardiac Surgery: A Retrospective Cohort Study.

BACKGROUND: Delayed cold storage of room temperature platelets may extend shelf life from 5 to 14 days. The study hypothesized that the use of delayed cold-stored platelets in cardiac surgery would be associated with decreased postoperative platelet count increments but similar transfusion and clinical outcomes compared to room temperature-stored platelets. METHODS: This is an observational cohort study of adults transfused with platelets intraoperatively during elective cardiac surgery between April 2020 and May 2021. Intraoperative platelets were either room temperature-stored or delayed cold-stored based on blood bank availability rather than clinical features or provider preference. Differences in transfusion and clinical outcomes, including a primary outcome of allogenic transfusion exposure in the first 24 h postoperatively, were compared between groups. RESULTS: A total of 713 patient encounters were included: 529 (74%) room temperature-stored platelets and 184 (26%) delayed cold-stored platelets. Median (interquartile range) intraoperative platelet volumes were 1 (1 to 2) units in both groups. Patients receiving delayed cold-stored platelets had higher odds of allogeneic transfusion in the first 24 h postoperatively (81 of 184 [44%] vs. 169 of 529 [32%]; adjusted odds ratio, 1.65; 95% CI, 1.13 to 2.39; P = 0.009), including both erythrocytes (65 of 184 [35%] vs. 135 of 529 [26%]; adjusted odds ratio, 1.54; 95% CI, 1.03 to 2.29; P = 0.035) and platelets (48 of 184 [26%] vs. 79 of 529 [15%]; adjusted odds ratio, 1.91; 95% CI, 1.22 to 2.99; P = 0.005). There was no difference in the number of units administered postoperatively among those transfused. Platelet counts were modestly lower in the delayed cold-stored platelet group (-9 × 109/l; 95% CI, -16 to -3]) through the first 3 days postoperatively. There were no significant differences in reoperation for bleeding, postoperative chest tube output, or clinical outcomes. CONCLUSIONS: In adults undergoing cardiac surgery, delayed cold-stored platelets were associated with higher postoperative transfusion utilization and lower platelet counts compared to room temperature-stored platelets without differences in clinical outcomes. The use of delayed cold-stored platelets in this setting may offer a viable alternative when facing critical platelet inventories but is not recommended as a primary transfusion approach.

Coagulation Tests and Bleeding Classification After Cardiopulmonary Bypass: A Prospective Study.

OBJECTIVE: No recent prospective studies have analyzed the accuracy of standard coagulation tests and thromboelastography (TEG) to identify patients with excessive microvascular bleeding following cardiopulmonary bypass (CPB). The aim of this study was to assess the value of coagulation profile tests, as well as TEG, for the classification of microvascular bleeding after CPB. DESIGN: A prospective observational study. SETTING: At a single-center academic hospital. PARTICIPANTS: Patients ≥18 years of age undergoing elective cardiac surgery. INTERVENTIONS: Qualitative assessment of microvascular bleeding post-CPB (surgeon and anesthesiologist consensus) and the association with coagulation profile tests and TEG values. MEASUREMENTS AND MAIN RESULTS: A total of 816 patients were included in the study-358 (44%) bleeders and 458 (56%) nonbleeders. Accuracy, sensitivity, and specificity for the coagulation profile tests and TEG values ranged from 45% to 72%. The predictive utility was similar across tests, with prothrombin time (PT) (62% accuracy, 51% sensitivity, 70% specificity), international normalized ratio (INR) (62% accuracy, 48% sensitivity, 72% specificity), and platelet count (62% accuracy, 62% sensitivity, 61% specificity) displaying the highest performance. Secondary outcomes were worse in bleeders versus nonbleeders, including higher chest tube drainage, total blood loss, transfusion of red blood cells, reoperation rates (p < 0.001, respectively), readmission within 30 days (p = 0.007), and hospital mortality (p = 0.021). CONCLUSIONS: Standard coagulation tests and individual components of TEG in isolation agree poorly with the visual classification of microvascular bleeding after CPB. The PT-INR and platelet count performed best but had low accuracy. Further work is warranted to identify better testing strategies to guide perioperative transfusion decisions in cardiac surgical patients.

Non-invasive hemoglobin estimation for preoperative anemia screening.

BACKGROUND: Preoperative anemia is common and associated with adverse postoperative outcomes. Assessment of hemoglobin concentrations may facilitate optimization prior to surgery. However, phlebotomy-based hemoglobin measurement may contribute to patient discomfort and iatrogenic blood loss, which makes non-invasive hemoglobin estimation attractive in this setting. STUDY DESIGN AND METHODS: This is a prospective study of adult patients presenting for preoperative evaluation before elective surgery at a tertiary care medical center. The Masimo Pronto Pulse CO-Oximeter was utilized to estimate blood hemoglobin concentrations (SpHb), which were then compared with hemoglobin concentrations obtained via complete blood count. Receiver operating curves were used to identify SpHb values maximizing specificity for anemia detection while meeting a minimum sensitivity of 80%. RESULTS: A total of 122 patients were recruited with a median (interquartile range) age of 66 (58, 72) years. SpHb measurements were obtained in 112 patients (92%). SpHb generally overestimated hemoglobin with a mean (± 1.96 × standard deviation) difference of 0.8 (-2.2, 3.9) g/dL. Preoperative anemia, defined by hemoglobin <12.0 g/dL in accordance with institutional protocol, was present in 22 patients (20%). The optimal SpHb cut-point to identify anemia was 13.5 g/dL: sensitivity 86%, specificity 81%, negative predictive value 96%, and positive predictive value 53%. Utilizing this cut-point, 60% (73/122) of patients could have avoided phlebotomy-based hemoglobin assessment, while an anemia diagnosis would have been missed in <3% (3/122). CONCLUSION: The use of SpHb devices for anemia screening in surgical patients is feasible with the potential to reliably rule-out anemia despite limited accuracy.

Practical Anemia Bundle for Sustained Blood Recovery (PABST-BR) in critical illness: a protocol for a randomised controlled trial.

INTRODUCTION: Anaemia is highly prevalent in critical illness and is associated with impaired outcomes during and after hospitalisation. However, the impact of interventions designed to attenuate or treat anaemia during critical illness on post-hospitalisation haemoglobin recovery and functional outcomes is unclear. METHODS AND ANALYSIS: The Practical Anemia Bundle for Sustained Blood Recovery (PABST-BR) clinical trial is a pragmatic, open-label, parallel group, single-centre, randomised clinical trial assessing the impact of a multifaceted anaemia prevention and treatment strategy versus standard care for improvement of haemoglobin concentrations and functional outcomes after critical illness. The intervention, which will be delivered early in critical illness for those with moderate-to-severe anaemia (ie, haemoglobin <100 g/L), includes three components: (1) optimised phlebotomy, (2) clinical decision support and (3) pharmacological anaemia treatment directed at the underlying aetiology of anaemia. In-person assessments will occur at 1 and 3 months post-hospitalisation for laboratory evaluations and multidimensional functional outcome assessments. The primary outcome is differences in haemoglobin concentrations between groups, with secondary endpoints of anaemia-related fatigue, physical function, cognition, mental health, quality of life, phlebotomy volumes and frequency, transfusions, readmissions and mortality through 1-year post-hospitalisation. ETHICS AND DISSEMINATION: The study has been approved by the Institutional Review Board of the Mayo Clinic in Minnesota, USA. A Data Safety Monitoring Plan has been created in accordance with the policies of the Institutional Review Board and the study funder, the National Heart, Lung and Blood Institute of the National Institutes of Health (NIH). The study will comply with NIH data sharing and dissemination policies. Results will be presented at national and international meetings and published in peer-reviewed journals. Designing and testing strategies to optimise haemoglobin recovery and improve functional outcomes after critical illness remain important research gaps. The PABST-BR trial will inform the development of a larger multicentre clinical trial. TRIAL REGISTRATION NUMBER: NCT05167734.

A Contemporary Analysis of Phlebotomy and Iatrogenic Anemia Development Throughout Hospitalization in Critically Ill Adults.

BACKGROUND: Anemia is common in critically ill patients and may be exacerbated through phlebotomy-associated iatrogenic blood loss. Differences in phlebotomy practice across patient demographic characteristics, clinical features, and practice environments are unclear. This investigation provides a comprehensive description of contemporary phlebotomy practices for critically ill adults. METHODS: This is an observational cohort study of adults ≥18 years of age requiring intensive care unit (ICU) admission between January 1, 2019, and December 31, 2019, at a large academic medical center. Descriptive statistics were utilized to summarize all phlebotomy episodes throughout hospitalization, with each phlebotomy episode defined by unique peripheral venous, central venous, or arterial accesses for laboratory draws, exclusive of finger sticks. Secondarily, financial costs of phlebotomy and the relationships between phlebotomy practices, hemoglobin concentrations, and red blood cell (RBC) transfusions were evaluated. RESULTS: A total of 6194 patients were included: 59% were men with a median (interquartile range) age of 66 (54-76) years and median ICU and hospital durations of 2.1 (1.4-3.9) and 7.1 (4.3-11.8) days, respectively. The median number of unique laboratory draws was 41 (18-88) throughout hospitalization, with a median volume of 232 (121-442) mL, corresponding to 5.2 (2.6-8.8) draws and 29 (19-43) mL per day. Waste (ie, discard) volume was responsible for 10.8% of total phlebotomy volume. Surgical patients had a higher number of phlebotomy episodes and greater total phlebotomy volumes compared to nonsurgical patients. Phlebotomy practices differed across ICU types, with the greatest frequency of laboratory draws in the cardiac surgical ICU and the greatest daily phlebotomy volume in the medical ICU. Across hospitalization, ICU environments had the greatest frequency and volumes of laboratory draws, with the least intensive phlebotomy practice observed in the general hospital wards. Patients in the highest quartile of cumulative blood drawn experienced the longest hospitalizations, lowest nadir hemoglobin concentrations, and greatest RBC transfusion utilization. Differences in phlebotomy practice were limited across patient age, gender, and race. Hemoglobin concentrations declined during hospitalization, congruent with intensity of phlebotomy practice. Each 100 mL of phlebotomy volume during hospitalization was associated with a 1.15 (95% confidence interval [CI], 1.14-1.17; P < .001) multiplicative increase in RBC units transfused in adjusted analyses. Estimated annual phlebotomy costs exceeded $15 million (approximately $2500 per patient admission). CONCLUSIONS: Phlebotomy continues to be a major source of blood loss in hospitalized patients with critical illness, and more intensive phlebotomy practices are associated with lower hemoglobin concentrations and greater transfusion utilization.

A Global Definition of Patient Blood Management.

While patient blood management (PBM) initiatives are increasingly adopted across the globe as part of standard of care, there is need for a clear and widely accepted definition of PBM. To address this, an expert group representing PBM organizations from the International Foundation for Patient Blood Management (IFPBM), the Network for the Advancement of Patient Blood Management, Haemostasis and Thrombosis (NATA), the Society for the Advancement of Patient Blood Management (SABM), the Western Australia Patient Blood Management (WAPBM) Group, and OnTrac (Ontario Nurse Transfusion Coordinators) convened and developed this definition: "Patient blood management is a patient-centered, systematic, evidence-based approach to improve patient outcomes by managing and preserving a patient's own blood, while promoting patient safety and empowerment." The definition emphasizes the critical role of informed choice. PBM involves the timely, multidisciplinary application of evidence-based medical and surgical concepts aimed at (1) screening for, diagnosing, and appropriately treating anemia; (2) minimizing surgical, procedural, and iatrogenic blood losses and managing coagulopathic bleeding throughout the care; and (3) supporting the patient while appropriate treatment is initiated. We believe that having a common definition for PBM will assist all those involved including PBM organizations, hospital administrators, individual clinicians, and policy makers to focus on the appropriate issues when discussing and implementing PBM. The proposed definition is expected to continue to evolve, making this endeavor a work in progress.

Early Post-Hospitalization Hemoglobin Recovery and Clinical Outcomes in Survivors of Critical Illness: A Population-Based Cohort Study.

Anemia is common during critical illness, is associated with adverse clinical outcomes, and often persists after hospitalization. The goal of this investigation is to assess the relationships between post-hospitalization hemoglobin recovery and clinical outcomes after survival of critical illness. This is a population-based observational study of adults (≥18 years) surviving hospitalization for critical illness between January 1, 2010 and December 31, 2016 in Olmsted County, Minnesota, United States with hemoglobin concentrations and clinical outcomes assessed through one-year post-hospitalization. Multi-state proportional hazards models were utilized to assess the relationships between 1-month post-hospitalization hemoglobin recovery and hospital readmission or death through one-year after discharge. Among 6460 patients that survived hospitalization for critical illness during the study period, 2736 (42%) were alive, not hospitalized, and had available hemoglobin concentrations assessed at 1-month post-index hospitalization. Median (interquartile range) age was 69 (56, 80) years with 54% of male gender. Overall, 86% of patients had anemia at the time of hospital discharge, with median discharge hemoglobin concentrations of 10.2 (9.1, 11.6) g/dL. In adjusted analyses, each 1 g/dL increase in 1-month hemoglobin recovery was associated with decreased instantaneous hazard for hospital readmission (HR 0.87 [95% CI 0.84-0.90]; p < 0.001) and lower mortality (HR 0.82 [95% CI 0.75-0.89]; p < 0.001) through one-year post-hospitalization. The results were consistent in multiple pre-defined sensitivity analyses. Impaired early post-hospitalization hemoglobin recovery is associated with inferior clinical outcomes in the first year of survival after critical illness. Additional investigations are warranted to evaluate these relationships.

Characterization of Platelet Biologic Markers in the Early Pathogenesis of Postoperative Acute Respiratory Distress Syndrome.

Animal models and limited human studies have suggested a plausible role for platelets in the pathogenesis and resolution of acute respiratory distress syndrome (ARDS). However, there are little data regarding the role of platelets in ARDS development. OBJECTIVES: The objective of this study was to characterize the role of platelets in a postoperative ARDS model through an analysis of two platelet-specific biologic markers: thromboxane A2 (TxA2) and soluble CD-40-ligand (sCD40L). DESIGN SETTING AND PARTICIPANTS: This was a nested case-control study of ARDS cases matched to non-ARDS controls. Blood samples were collected from a cohort of 500 patients undergoing thoracic, aortic vascular, or cardiac surgery that placed them at high-risk of developing postoperative ARDS. MAIN OUTCOMES AND MEASURES: TxA2 and sCD40L were analyzed at baseline (prior to surgical incision) as well as 2 hours and 6 hours after the key intraoperative events believed to be associated with increased risk of postoperative ARDS. RESULTS: Of 500 patients enrolled, 20 ARDS cases were matched 1:2 to non-ARDS controls based on age, sex, surgical procedure, and surgical lung injury prediction score. Those who developed ARDS had longer surgeries, greater fluid administration, and higher peak inspiratory pressures. There were no significant differences in levels of TxA2 or sCD40L at baseline, at 2 hours, or at 6 hours. There was also no difference in the change in biomarker concentration between baseline and 2 hours or baseline and 6 hours. CONCLUSIONS: Two novel platelet-associated biologic markers (TxA2 and sCD40L) were not elevated in patients who developed ARDS in a postoperative ARDS model. Although limited by the relatively small study size, these results do not support a clear role for platelets in the early pathogenesis of postoperative ARDS.

Plasma, platelet and red blood cell transfusion ratios for life-threatening non-traumatic haemorrhage in medical and post-surgical patients: An observational study.

BACKGROUND AND OBJECTIVES: Despite the broad utilization of component-based transfusion strategies that aim to reconstitute whole blood during acute traumatic haemorrhage, data for haemorrhage occurring outside of trauma and surgery are limited. METHODS: This is an observational cohort study of adults experiencing critical non-traumatic, non-intraoperative haemorrhage during hospitalization at an academic medical centre from 2011 to 2015. The primary goal was to evaluate differences in plasma and platelet to red blood cell (RBC) transfusion ratios across patient demographic, clinical and laboratory characteristics. Secondarily, associations between transfusion ratios and clinical outcomes were assessed. RESULTS: Seven hundred nine patients were included: 498 (70.2%) medical and 211 (29.8%) post surgical. The gastrointestinal tract (36.7%) was the most common site of bleeding. Most patients received RBCs without plasma (35.5%) or platelets (54.2%). Among those receiving plasma, 82.3% received a plasma to RBC ratio < 1:1 at 24 h. For platelets, the most common ratio was 1-2:1 (52.9%). Transfusion ratios were generally consistent across comorbid disease severity, admission type and anatomic sites of bleeding. Higher plasma utilization was observed in the emergency department, while greater platelet utilization occurred in intensive care units. Higher transfusion ratios were observed in those with greater laboratory haemostatic abnormalities prior to the haemorrhagic event. Clinical outcome differences were limited, though greater platelet utilization in the first 24 h was associated with higher mortality and fewer hospital-free days. CONCLUSIONS: Transfusion ratios for critical non-traumatic haemorrhage were primarily related to laboratory abnormalities preceding the haemorrhagic event and practice environments. Clinical outcome differences across ratios were limited.

Implementation of a Comprehensive Patient Blood Management Program for Hospitalized Patients at a Large United States Medical Center.

OBJECTIVE: To assess changes in inpatient transfusion utilization and patient outcomes with implementation of a comprehensive patient blood management (PBM) program at a large US medical center. PATIENTS AND METHODS: This is an observational study of graduated PBM implementation for hospitalized adults (age ≥18 years) from January 1, 2010, through December 31, 2017, at two integrated hospital campuses at a major academic US medical center. Allogeneic transfusion utilization and clinical outcomes were assessed over time through segmented regression with multivariable adjustment comparing observed outcomes against projected outcomes in the absence of PBM activities. RESULTS: In total, 400,998 admissions were included. Total allogeneic transfusions per 1000 admissions decreased from 607 to 405 over the study time frame, corresponding to an absolute risk reduction for transfusion of 6.0% (95% confidence interval [CI]: 3.6%, 8.3%; P<.001) and a 22% (95% CI: 6%, 37%; P=.006) decrease in the rate of transfusions over projected. The risk of transfusion decreased for all blood components except cryoprecipitate. Transfusion reductions were experienced for all major surgery types except liver transplantation, which remained stable over time. Hospital length of stay (multiplicative increase in geometric mean 0.85 [95% CI: 0.81, 0.89]; P<.001) and incident in-hospital adverse events (absolute risk reduction: 1.5% [95% CI: 0.1%, 3.0%]; P=.04) were lower than projected at the end of the study time frame. CONCLUSION: Patient blood management implementation for hospitalized patients in a large academic center was associated with substantial reductions in transfusion utilization and improved clinical outcomes. Broad-scale implementation of PBM in US hospitals is feasible without signal for patient harm.

Quantifying the Importance of COVID-19 Vaccination to Our Future Outlook.

Predictive models have played a critical role in local, national, and international response to the COVID-19 pandemic. In the United States, health care systems and governmental agencies have relied on several models, such as the Institute for Health Metrics and Evaluation, Youyang Gu (YYG), Massachusetts Institute of Technology, and Centers for Disease Control and Prevention ensemble, to predict short- and long-term trends in disease activity. The Mayo Clinic Bayesian SIR model, recently made publicly available, has informed Mayo Clinic practice leadership at all sites across the United States and has been shared with Minnesota governmental leadership to help inform critical decisions during the past year. One key to the accuracy of the Mayo Clinic model is its ability to adapt to the constantly changing dynamics of the pandemic and uncertainties of human behavior, such as changes in the rate of contact among the population over time and by geographic location and now new virus variants. The Mayo Clinic model can also be used to forecast COVID-19 trends in different hypothetical worlds in which no vaccine is available, vaccinations are no longer being accepted from this point forward, and 75% of the population is already vaccinated. Surveys indicate that half of American adults are hesitant to receive a COVID-19 vaccine, and lack of understanding of the benefits of vaccination is an important barrier to use. The focus of this paper is to illustrate the stark contrast between these 3 scenarios and to demonstrate, mathematically, the benefit of high vaccine uptake on the future course of the pandemic.

Deployment of an Interdisciplinary Predictive Analytics Task Force to Inform Hospital Operational Decision-Making During the COVID-19 Pandemic.

In March 2020, our institution developed an interdisciplinary predictive analytics task force to provide coronavirus disease 2019 (COVID-19) hospital census forecasting to help clinical leaders understand the potential impacts on hospital operations. As the situation unfolded into a pandemic, our task force provided predictive insights through a structured set of visualizations and key messages that have helped the practice to anticipate and react to changing operational needs and opportunities. The framework shared here for the deployment of a COVID-19 predictive analytics task force could be adapted for effective implementation at other institutions to provide evidence-based messaging for operational decision-making. For hospitals without such a structure, immediate consideration may be warranted in light of the devastating COVID-19 third-wave which has arrived for winter 2020-2021.

Sex-Specific Associations Between Preoperative Anemia and Postoperative Clinical Outcomes in Patients Undergoing Cardiac Surgery.

BACKGROUND: Preoperative anemia is common in cardiac surgery, yet there were limited data describing the role of sex in the associations between anemia and clinical outcomes. Understanding these relationships may guide preoperative optimization efforts. METHODS: This is an observational cohort study of adults undergoing isolated coronary artery bypass grafting or single- or double-valve surgery from 2008 to 2018 at a large tertiary medical center. Multivariable regression assessed the associations between preoperative hemoglobin concentrations and a primary outcome of postoperative acute kidney injury (AKI) and secondary outcomes of perioperative red blood cell (RBC) transfusion, reoperation, vascular complications (ie, stroke, pulmonary embolism, and myocardial infarction), and hospital length of stay (LOS). Each outcome was a single regression model, using interaction terms to assess sex-specific associations between hemoglobin and outcome. RESULTS: A total of 4117 patients were included (57% men). Linear splines with sex-specific knots (13 g/dL in women and 14 g/dL in men) provided the best overall fit for preoperative hemoglobin and outcome relationships. In women, each 1 g/dL decrease in hemoglobin <13 g/dL was associated with increased odds of AKI (odds ratio = 1.49; 95% confidence interval [CI], [1.23-1.81]; P < .001), and there was no significant association between hemoglobin per 1 g/dL >13 g/dL and AKI (0.90 [0.56-1.45]; P = .67). The association between hemoglobin and AKI in men did not meet statistical significance (1.10 [0.99-1.22]; P = .076, per 1 g/dL decrease <14 g/dL; 1.00 [0.79-1.26]; P = .98 for hemoglobin per 1 g/dL >14 g/dL). In women, lower preoperative hemoglobin (per 1 g/dL decrease <13 g/dL) was associated with increased odds of RBC transfusion (2.90 [2.33-3.60]; P < .001), reoperation (1.27 [1.11-1.45]; P < .001) and a longer hospital LOS (multiplicative increase in geometric mean 1.05 [1.03-1.07]; P < .001). In men, preoperative hemoglobin (per 1 g/dL decrease <14 g/dL) was associated with increased odds of perioperative RBCs (2.56 [2.27-2.88]; P < .001) and longer hospital LOS (multiplicative increase in geometric mean 1.02 [1.01-1.04] days; P < .001) but not reoperation (0.94 [0.85-1.04]; P = .256). Preoperative hemoglobin per 1 g/dL >13 g/dL in women and 14 g/dL in men were associated with lower odds of RBCs transfusion (0.57 [0.47-0.69]; P < .001 and 0.74 [0.60-0.91]; P = .005, respectively). CONCLUSIONS: Preoperative anemia was associated with inferior clinical outcomes after cardiac surgery. The associations between hemoglobin and outcomes were distinct for women and men, with different spline knot points identified (13 and 14 g/dL, respectively). Clinicians should consider data-driven approaches to determine preoperative hemoglobin values associated with increasing risk for adverse perioperative outcomes across sexes.

Red blood cell transfusion threshold and mortality in cardiac intensive care unit patients.

BACKGROUND: The benefit of red blood cell (RBC) transfusion in anemic critically-ill patients with cardiovascular disease is uncertain, as is the optimal threshold at which RBC transfusion should be considered. We sought to examine the association between RBC transfusion and mortality stratified by nadir Hgb level and admission diagnosis among cardiac intensive care unit (CICU) patients. METHODS: Retrospective single-center cohort of 11,754 CICU patients admitted between 2007 and 2018. The association between RBC transfusion and hospital mortality at each nadir Hgb (<8 g/dL, 8-9.9 g/dL, ≥10 g/dL) was assessed using multivariable logistic regression adjusted for the propensity to receive RBC transfusion. RESULTS: The study population had a mean age of 68±15 years, including 38% females; 1,134 (11.4%) received RBC transfusion. Admission diagnoses included: acute coronary syndrome , 42%; heart failure, 50%; cardiac arrest , 12%; and cardiogenic shock , 12%. Patients who received RBC transfusion had higher crude hospital mortality (19% vs. 8%, P<.001). RBC transfusion was associated with lower adjusted hospital mortality in patients with nadir Hgb <8 g/dL after propensity adjustment, including subgroups with acute coronary syndrome, cardiac arrest, or cardiogenic shock (all P <.01). RBC transfusion was not associated with lower adjusted hospital mortality in any subgroup of patients with nadir Hgb ≥8 g/dL. CONCLUSIONS: These observational data suggest the use of a Hgb threshold <8 g/dL for RBC transfusion in most CICU patients, although we could not exclude a potential benefit of RBC transfusion at a nadir Hgb of 8 to 9.9 g/dL; we did not observe any benefit from RBC transfusion at a nadir Hgb ≥10 g/dL.

Bedside Allogeneic Erythrocyte Washing with a Cell Saver to Remove Cytokines, Chemokines, and Cell-derived Microvesicles.

BACKGROUND: Removal of cytokines, chemokines, and microvesicles from the supernatant of allogeneic erythrocytes may help mitigate adverse transfusion reactions. Blood bank-based washing procedures present logistical difficulties; therefore, we tested the hypothesis that on-demand bedside washing of allogeneic erythrocyte units is capable of removing soluble factors and is feasible in a clinical setting. METHODS: There were in vitro and prospective, observation cohort components to this a priori planned substudy evaluating bedside allogeneic erythrocyte washing, with a cell saver, during cardiac surgery. Laboratory data were collected from the first 75 washed units given to a subset of patients nested in the intervention arm of a parent clinical trial. Paired pre- and postwash samples from the blood unit bags were centrifuged. The supernatant was aspirated and frozen at -70°C, then batch-tested for cell-derived microvesicles, soluble CD40 ligand, chemokine ligand 5, and neutral lipids (all previously associated with transfusion reactions) and cell-free hemoglobin (possibly increased by washing). From the entire cohort randomized to the intervention arm of the trial, bedside washing was defined as feasible if at least 75% of prescribed units were washed per protocol. RESULTS: Paired data were available for 74 units. Washing reduced soluble CD40 ligand (median [interquartile range]; from 143 [1 to 338] ng/ml to zero), chemokine ligand 5 (from 1,314 [715 to 2,551] to 305 [179 to 488] ng/ml), and microvesicle numbers (from 6.90 [4.10 to 20.0] to 0.83 [0.33 to 2.80] × 106), while cell-free hemoglobin concentration increased from 72.6 (53.6 to 171.6) mg/dl to 210.5 (126.6 to 479.6) mg/dl (P < 0.0001 for each). There was no effect on neutral lipids. Bedside washing was determined as feasible for 80 of 81 patients (99%); overall, 293 of 314 (93%) units were washed per protocol. CONCLUSIONS: Bedside erythrocyte washing was clinically feasible and greatly reduced concentrations of soluble factors thought to be associated with transfusion-related adverse reactions, increasing concentrations of cell-free hemoglobin while maintaining acceptable (less than 0.8%) hemolysis.

The Prevalence and Clinical Significance of Preoperative Thrombocytopenia in Adults Undergoing Elective Surgery: An Observational Cohort Study.

BACKGROUND: Preoperative thrombocytopenia is associated with inferior outcomes in surgical patients, though concurrent anemia may obfuscate these relationships. This investigation assesses the prevalence and clinical significance of preoperative thrombocytopenia with thorough consideration of preoperative anemia status. METHODS: This is an observational cohort study of adults undergoing elective surgery with planned postoperative hospitalization from January 1, 2009 to May 3, 2018. Patients were designated into 4 groups: normal platelet and hemoglobin concentrations, isolated thrombocytopenia (ie, platelet count <100 × 109/L), isolated anemia (ie, hemoglobin <12 g/dL women, <13.5 g/dL men), and thrombocytopenia with anemia. Thrombocytopenia was further defined as incidental (ie, previously undiagnosed) or nonincidental. Multivariable regression analyses were utilized to assess the relationships between thrombocytopenia status and clinical outcomes, with a primary outcome of hospital length of stay. RESULTS: A total of 120,348 patients were included for analysis: 72.3% (95% confidence interval [CI], 72.1-72.6) normal preoperative laboratory values, 26.3% (26.1-26.6) isolated anemia, 0.80% (0.75-0.86) thrombocytopenia with anemia, and 0.52% (0.48-0.56) isolated thrombocytopenia (0.38% [0.34-0.41] nonincidental, 0.14% [0.12-0.17] incidental). Thrombocytopenia was associated with longer hospital length of stay in those with concurrent anemia (multiplicative increase of the geometric mean 1.05 [1.00, 1.09] days; P = .034) but not in those with normal preoperative hemoglobin concentrations (multiplicative increase of the geometric mean 1.02 [0.96, 1.07] days; P = .559). Thrombocytopenia was associated with increased odds for intraoperative transfusion regardless of anemia status (nonanemic: 3.39 [2.79, 4.12]; P < .001 vs anemic: 2.60 [2.24, 3.01]; P < .001). Thrombocytopenia was associated with increased rates of intensive care unit (ICU) admission in nonanemic patients (1.56 [1.18, 2.05]; P = .002) but not in those with preoperative anemia (0.93 [0.73, 1.19]; P = .578). CONCLUSIONS: Preoperative thrombocytopenia is associated with clinical outcomes in elective surgery, both in the presence and absence of concurrent anemia. However, isolated thrombocytopenia is rare (0.5%) and is usually identified before preoperative testing. It is unlikely that routine thrombocytopenia screening is indicated for most patients.

Renal Function Parameters and Serum Sodium Enhance Prediction of Wait-List Outcomes in Pediatric Liver Transplantation.

BACKGROUND AND AIMS: Reliance on exception points to prioritize children for liver transplantation (LT) stems from concerns that the Pediatric End-Stage Liver Disease (PELD) score underestimates mortality. Renal dysfunction and serum sodium disturbances are negative prognosticators in adult LT candidates and various pediatric populations, but are not accounted for in PELD. We retrospectively evaluated the effect of these parameters in predicting 90-day wait-list death/deterioration among pediatric patients (<12 years) listed for isolated LT in the United States between February 2002 and June 2018. APPROACH AND RESULTS: Among 4,765 patients, 2,303 (49.3%) were transplanted, and 231 (4.8%) died or deteriorated beyond transplantability within 90 days of listing. Estimated glomerular filtration rate (eGFR) (hazard ratio [HR] 1.09 per 5-unit decrease, 95% confidence interval [CI] 1.06-1.10) and dialysis (HR 7.24, 95% CI 3.57-14.66) were univariate predictors of 90-day death/deterioration (P < 0.001). The long-term benefit of LT persisted in patients with renal dysfunction, with LT as a time-dependent covariate conferring a 2.4-fold and 17-fold improvement in late survival among those with mild and moderate-to-severe dysfunction, respectively. Adjusting for PELD, sodium was a significant nonlinear predictor of outcome, with 90-day death/deterioration risk increased at both extremes of sodium (HR 1.20 per 1-unit decrease below 137 mmol/L, 95% CI 1.16-1.23; HR per 1-unit increase above 137 mmol/L 1.13, 95% CI 1.10-1.17, P < 0.001). A multivariable model incorporating PELD, eGFR, dialysis, and sodium demonstrated improved performance and superior calibration in predicting wait-list outcomes relative to the PELD score. CONCLUSIONS: Listing eGFR, dialysis, and serum sodium are potent, independent predictors of 90-day death/deterioration in pediatric LT candidates, capturing risk not accounted for by PELD. Incorporation of these variables into organ allocation systems may highlight patient subsets with previously underappreciated risk, augment ability of PELD to prioritize patients for transplantation, and ultimately mitigate reliance on nonstandard exceptions.