Initial Postoperative Hemoglobin Values and Clinical Outcomes in Transfused Patients Undergoing Noncardiac Surgery

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.

The impact of preoperative serum lactate dehydrogenase on mortality and morbidity after noncardiac surgery

Preoperative serum lactate dehydrogenase (LDH) has been reported to be associated with adverse outcomes following thoracic surgery. However, its association with outcomes in noncardiac surgery as a whole has not been investigated. We conducted a retrospective cohort study at West China Hospital, Sichuan University, from 2018 to 2020, including patients undergoing noncardiac surgery. Multivariable logistic regression and propensity score weighting were employed to assess the link between LDH levels and postoperative outcomes. Preoperative LDH was incorporated into four commonly used clinical models, and its discriminative ability, reclassification, and calibration were evaluated in comparison to models without LDH. Among 130,879 patients, higher preoperative LDH levels (cut-off: 220 U/L) were linked to increased in-hospital mortality (4.382% vs. 0.702%; OR 1.856, 95% CI 1.620-2.127, P < 0.001), myocardial injury after noncardiac surgery (MINS) (3.012% vs. 0.537%; OR 1.911, 95% CI 1.643-2.223, P < 0.001), and ICU admission (15.010% vs. 6.414%; OR 1.765, 95% CI 1.642-1.896, P < 0.001). The inverse probability of treatment-weighted estimation supported these results. Additionally, LDH contributed significantly to four surgical prognostic models, enhancing their predictive capability. Our study revealed a significant association between preoperative LDH and in-hospital mortality, MINS, and ICU admission following noncardiac surgery. Moreover, LDH provided supplementary predictive information, extending the utility of commonly used surgical prognostic scores.

Nadir Hemoglobin Concentration After Spinal Tumor Surgery: Association With Risk of Composite Adverse Events

STUDY DESIGN

Retrospective case-control study.

OBJECTIVE

To explore the association of early postoperative nadir hemoglobin with risk of a composite outcome of anemia-related and other adverse events.

METHODS

We retrospectively analyzed data from spinal tumor patients who received intraoperative blood transfusion between September 1, 2013 and December 31, 2020. Uni- and multivariate logistic regression was used to explore relationships of clinicodemographic and surgical factors with risk of composite in-hospital adverse events, including death. Subgroup analysis explored the relationship between early postoperative nadir hemoglobin and composite adverse events.

RESULTS

Among the 345 patients, 331 (95.9%) experienced early postoperative anemia and 69 (20%) experienced postoperative composite adverse events. Multivariate logistic regression analysis showed that postoperative nadir Hb (OR = .818, 95% CI: .672-.995, P = .044), ASA ≥3 (OR = 2.007, 95% CI: 1.086-3.707, P = .026), intraoperative RBC infusion volume (OR = 1.133, 95% CI: 1.009-1.272, P = .035), abnormal hypertension (OR = 2.199, 95% CI: 1.085-4.457, P = .029) were correlated with composite adverse events. The lumbar spinal tumor was associated with composite adverse events with a decreased odds compared to thoracic spinal tumors (OR = .444, 95% CI: .226-.876, P = .019). Compared to patients with postoperative nadir hemoglobin ≥11.0 g/dL, those with nadir <9.0 g/dL were at significantly higher risk of postoperative composite adverse events (OR = 2.709, 95% CI: 1.087-6.754, P = .032).

CONCLUSION

Nadir hemoglobin <9.0 g/dL after spinal tumor surgery is associated with greater risk of postoperative composite adverse events in patients who receive intraoperative blood transfusion.

Patient Blood Management, Anemia, and Transfusion Optimization Across Surgical Specialties

Patient blood management (PBM) is a systematic, evidence-based approach to improve patient outcomes by managing and preserving a patient's own blood and minimizing allogenic transfusion need and risk. According to the PBM approach, the goals of perioperative anemia management include early diagnosis, targeted treatment, blood conservation, restrictive transfusion except in cases of acute and massive hemorrhage, and ongoing quality assurance and research efforts to advance overall blood health.

Threshold heterogeneity of perioperative hemoglobin drop for acute kidney injury after noncardiac surgery: a propensity score weighting analysis

Background

Perioperative hemoglobin drop after noncardiac surgery is associated with acute kidney injury (AKI). However, opinion on the tolerable difference in postoperative hemoglobin drop in patients with different preoperative hemoglobin levels does not reach a consensus. This study aimed to identify hemoglobin drop thresholds for AKI after noncardiac surgery stratified by preoperative hemoglobin levels.

Method

This was a single-center retrospective cohort study for elective noncardiac surgery from January 1, 2012, to December 31, 2018. The endpoint was the occurrence of AKI 7 days postoperatively in the hospital. The generalized additive model described the non-linear relationship between hemoglobin drop and AKI occurrence. The minimum P-value approach identified cut-off points of hemoglobin drop within postoperative 7 days for patients with or without preoperative anemia. Stratified by preoperative anemia, hemoglobin drop’s odds ratio as continuous, quintile and dichotomous variables by various cut-off points for postoperative AKI were calculated in multivariate logistic regression models before and after propensity score weighting (PSW).

Results

Of the 35,631 surgery, 5.9% (2105 cases) suffered postoperative AKI. Non-linearity was found between hemoglobin drop and postoperative AKI occurrence. The thresholds and corresponding odds ratio of perioperative hemoglobin drop for patients with and without preoperative anemia were 18 g/L (1.38 (95%CI 1.14 -1.62), P < .001; after PSW: 1.42 (95%CI 1.17 -1.74), P < .001) and 43 g/L (1.81 (95%CI 1.35—2.27), P < .001; after PSW: 2.88 (95%CI 1.85—4.50), P < .001) respectively. Overall thresholds and corresponding odds ratio were 43 g/L (1.82 (95%CI 1.42—2.21)), P < .001; after PSW: 3.29 (95%CI 2.00—5.40), P < .001). Sensitivity analysis showed similar results. Heterogeneity subgroup analysis showed that intraoperatively female patients undergoing intraperitoneal surgery without colloid infusion seemed to be more vulnerable to higher hemoglobin drop. Further analysis showed a possible linear relationship between preoperative hemoglobin and perioperative hemoglobin drop thresholds. Additionally, this study found that the creatinine level changed simultaneously with hemoglobin level within five postoperative days.

Conclusions

Heterogeneity of hemoglobin drop endurability exists after noncardiac non-kidney surgery. More care and earlier intervention should be put on patients with preoperative anemia.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12882-022-02834-3.

Incidence and Perioperative Risk Factors of Acute Kidney Injury Among Lung Transplant Recipients

BACKGROUND

Acute kidney injury (AKI) is a significant burden in an early postoperative period after lung transplantation (LT). The development of severe AKI, including a need for continuous renal replacement therapy (CRRT), is associated with increased mortality among lung transplant recipients. Evaluation of AKI incidence and predictive factors related to the development of severe AKI and with the use of CRRT in the early postoperative period after LT.

METHODS

Retrospective study of 73 consecutive patients after LT operated between 2015 and 2018 in our center. We noted the stage of AKI according to KDIGO guidelines in the 7 postoperative days.

RESULTS

We noted AKI among 62 lung transplant recipients (84.9%). We recognized the first and second stages of AKI in 21 patients (28.8%) and 19 patients 26%, respectively (group A). We identified severe AKI (group C) in 22 recipients (30.1%), 9 of whom needed CRRT postoperatively. There was a nonsignificant difference between groups in baseline serum creatinine (0.69 ± 0.22 mg/dL vs 0.84 ± 0.34; P = .073). Group C subjects statistically more often suffered from pulmonary hypertension (P < .001) and diabetes (P < .001). In both groups, the duration of the procedure was comparable, but, among patients with severe AKI, procedures were performed more often with the use of extracorporeal circulation (50% vs 68%; P = .194) CONCLUSIONS: Pulmonary hypertension and diabetes could be significant risk factors of high-grade AKI development after LT. Identification of factors modifying renal insufficiency development in lung transplant recipients needs further investigations.

Principles for minimizing oxygen debt: can they translate to clinical application and improve outcomes?

Oxygen delivery is dependent on pulmonary gas exchange, cardiac output, blood oxygen-carrying capacity, and tissue oxygen extraction. Reduction in oxygen delivery or higher oxygen consumption can initiate complex protective cellular processes precipitating oxygen debt. In critically ill and potentially surgical patients, stress and consequent hormonal or metabolic changes can trigger oxygen debt which is associated with worse morbidity and mortality. Increase in oxygen delivery by augmenting cardiac output or by increasing fraction of inspired oxygen (FiO₂) can help reduce oxygen debt. However, the extent of oxygen debt in an individual patient is poorly defined and difficult to measure. Furthermore, large heterogeneity in clinical trials assessing outcomes benefit of increasing oxygen delivery limits our ability to recommend goal directed fluid therapy aimed at increasing cardiac ouput or higher FiO₂. To understand and prevent oxygen debt in critically ill and surgical patients, we need to develop continuous monitoring techniques to assess the balance of oxygen delivery and consumption. Furthermore, methods of increasing oxygen delivery like goal-directed fluid therapy, higher FiO₂ and anemia prevention should be rigorously evaluated with focus on establishing outcomes benefit.

Incidence and Predictive Factors of Acute Kidney Injury After Off-pump Lung Transplantation

OBJECTIVES

To determine the incidence and predictive factors of acute kidney injury (AKI) after off-pump lung transplantation.

DESIGN

A retrospective cohort study.

SETTING

The operating room and intensive care unit.

PARTICIPANTS

Adult patients who underwent lung transplant without cardiopulmonary bypass or extracorporeal membrane oxygenator between 2006 and 2016 at the Vanderbilt University Medical Center.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The presence of postoperative AKI was assessed by the Kidney Disease: Improving Global Outcomes criteria in the first seven postoperative days. Multivariate logistic regression analysis was used to determine the independent predictive factors of AKI. One hundred forty-eight patients were included in the final analysis, of whom 63 (42.6%) subsequently developed AKI: 43 (29.0%) stage 1, ten (6.8%) stage 2, and ten (6.8%) stage 3. Patients who had AKI had a longer hospital length of stay (12 days [interquartile range (IQR): 10-17] vs ten days [IQR: 8-12], p < 0.001). For every one-year increase in age, the odds of AKI decreased by 8% (odds ratio [OR] 0.92, 95% confidence interval [CI]: 0.87-0.98, p = 0.008). The odds of having AKI in patients with bilateral lung transplant was lower than patients with unilateral transplant (OR 0.09, 95% CI: 0.01-0.63, p = 0.015). Additionally, a diagnosis of chronic obstructive pulmonary disease increased the odds of AKI by four-fold compared with a diagnosis of idiopathic pulmonary fibrosis (OR 4.73, 95% CI: 1.44-15.56, p = 0.011).

CONCLUSIONS

AKI is a common complication after off-pump lung transplantation and is associated with increased hospital length of stay. Younger age, unilateral lung transplant, and diagnosis of chronic obstructive pulmonary disease are independently associated with AKI.

Perioperative Transfusion Associated With Increased Morbidity and Mortality in Geriatric Patients Undergoing Hip Fracture Surgery

Introduction:

Both conservative and liberal transfusion thresholds, in regard to hematocrit and hemoglobin levels, have been widely studied with varying outcomes. The aim of this study was to evaluate if transfusion administered peri- (anytime during the admission), pre-, intra-, or postoperatively an its association with morbidity and mortality in the geriatric population undergoing hip surgery.

Methods:

This study was an institutional review board approved retrospective analysis of data collected from 841 patients at a single urban institution who underwent surgical repairs for hip fractures from 2008 to 2010.

Results:

Our analysis included data from 841 surgical patients. Mean patient age was 83, 74% were female, 48% received spinal anesthesia while 52% underwent general anesthesia. Out of 841 patients, 425 were transfused during the perioperative period. Most transfusions occurred postoperatively. Perioperative, intraoperative and postoperative transfusion was associated with an increase in post-operative AKI. Intraoperative blood transfusion was associated with an increase in morbidity (11.6% increased to 22.2%) by 1.9 fold, AKI (3.9% increased to 11.1%) by 2.8 fold, as well as an increase in mortality (5.2 increased to 15.6%) within 60 days by 3 fold.

Conclusions:

This may suggest that patients transfused prior to surgery, despite having met a specific trigger hemoglobin level earlier, may have been treated before deteriorating to a point that would cause future systemic implications.

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.

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.

Impact of body weight on hemoglobin increments in adult red blood cell transfusion

BACKGROUND

Though weight is a major consideration when transfusing blood in pediatric patients, it is generally not considered when dosing transfusions in adults. We hypothesized that the change in hemoglobin (Hb) concentration is inversely proportional to body weight when transfusing red blood cells (RBC) in adults.

METHODS

A total of 13,620 adult surgical patients at our institution were assessed in this retrospective cohort study (2009-2016). Patients were stratified based on total body weight (kg): 40-59.9 (16.6%), 60-79.9 (40.4%), 80-99.9 (28.8%), 100-119.9 (11.3%), and 120-139.9 (2.9%). The primary outcome was the change in Hb per RBC unit transfused. Subgroup analyses were performed after stratification by sex (male/female) and the total number of RBC units received (1/2/≥3 units). Multivariable models were used to assess the association between weight and change in Hb.

RESULTS

As patients' body weight increased, there was a decrease in the mean change in Hb per RBC unit transfused (40-59.9 kg: 0.85 g/dL, 60-79.9 kg: 0.73 g/dL, 80-99.9 kg: 0.66 g/dL, 100-119.9 kg: 0.60 g/dL, 120-139.9 kg: 0.55 g/dL; p < .0001). This corresponded with a 35% difference in the change in Hb between the lowest and highest weight categories on univariate analysis. Similar trends were seen after subgroup stratification. On multivariable analysis, for every 20 kg increase in patient weight, there was a ~6.5% decrease in the change in Hb per RBC unit transfused (p < .0001).

CONCLUSIONS

Patient body weight differentially impacts the change in Hb after RBC transfusion. These findings justify incorporating body weight into the clinical decision-making process when transfusing blood in adult surgical patients.

Machine Learning for the Prediction of Red Blood Cell Transfusion in Patients During or After Liver Transplantation Surgery

Aim: This study aimed to use machine learning algorithms to identify critical preoperative variables and predict the red blood cell (RBC) transfusion during or after liver transplantation surgery. Study Design and Methods: A total of 1,193 patients undergoing liver transplantation in three large tertiary hospitals in China were examined. Twenty-four preoperative variables were collected, including essential population characteristics, diagnosis, symptoms, and laboratory parameters. The cohort was randomly split into a train set (70%) and a validation set (30%). The Recursive Feature Elimination and eXtreme Gradient Boosting algorithms (XGBOOST) were used to select variables and build machine learning prediction models, respectively. Besides, seven other machine learning models and logistic regression were developed. The area under the receiver operating characteristic (AUROC) was used to compare the prediction performance of different models. The SHapley Additive exPlanations package was applied to interpret the XGBOOST model. Data from 31 patients at one of the hospitals were prospectively collected for model validation. Results: In this study, 72.1% of patients in the training set and 73.2% in the validation set underwent RBC transfusion during or after the surgery. Nine vital preoperative variables were finally selected, including the presence of portal hypertension, age, hemoglobin, diagnosis, direct bilirubin, activated partial thromboplastin time, globulin, aspartate aminotransferase, and alanine aminotransferase. The XGBOOST model presented significantly better predictive performance (AUROC: 0.813) than other models and also performed well in the prospective dataset (accuracy: 76.9%). Discussion: A model for predicting RBC transfusion during or after liver transplantation was successfully developed using a machine learning algorithm based on nine preoperative variables, which could guide high-risk patients to take appropriate preventive measures.

Initial Postoperative Hemoglobin Values Are Independently Associated With One-Year Mortality in Patients Undergoing Double-Lung Transplantation Requiring Intraoperative Transfusion

OBJECTIVE

To evaluate the association of postoperative hemoglobin values and mortality in patients undergoing double- lung transplantation with intraoperative transfusion.

DESIGN

Retrospective cohort study.

SETTING

University hospital.

PARTICIPANTS

Adult patients who underwent double-lung transplantation at the authors' institution, with intraoperative transfusion of packed red blood cells between 2009 and 2015.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Intraoperative transfusion requirements and general characteristics of 554 patients were collected. A generalized additive model, controlling for postoperative hemoglobin levels, number of transfused units of packed red blood cells, perioperative change in hemoglobin levels, disease leading to lung transplantation, and postoperative extracorporeal membrane oxygenation, was created to predict one-year mortality. A postoperative hemoglobin level of 11.3 g/dL was calculated as an optimal cutoff point. The patients were stratified according to this level. The end -point was all-cause one-year mortality after double-lung transplantation, assessed using the Kaplan-Meier analysis with log-rank test. All-cause mortality of the 554 patients was 17%. Postoperatively, 171 patients (31%) were categorized as being below the cutoff point. Improved survival was observed in the group with higher postoperative hemoglobin values (p = 0.002).

CONCLUSION

Lower postoperative hemoglobin levels in double-lung transplantation recipients were associated with increased mortality during the first year after surgery. Confirmation of these findings in additional investigations could alter patient blood management for double-lung transplantation.

Hospital discharge hemoglobin values and posthospitalization clinical outcomes in transfused patients undergoing noncardiac surgery

BACKGROUND

Red blood cell (RBC) transfusion is common in surgical patients, yet optimal transfusion targets are incompletely defined in the perioperative period. Hemoglobin levels at the time of hospital discharge may provide insight into transfusion practices, anemia management, and patient outcomes.

STUDY DESIGN AND METHODS

This is an observational cohort study of adults receiving RBC transfusion during noncardiac surgery from 2010 to 2014. Multivariable regression was used to assess the relationships between hospital discharge hemoglobin concentrations, anemia severity (severe: <8 g/dL; moderate: 8-10 g/dL; mild/none: ≥10 g/dL), and clinical outcomes, including a primary outcome of 30-day hospital readmission and secondary outcomes of posthospitalization RBC transfusion, composite stroke or myocardial infarction, and mortality.

RESULTS

A total of 3129 patients were included: 165 (5%) with severe discharge anemia, 1962 (63%) moderate, and 1002 (32%) with mild/none. Five hundred ninety-two (19%) were readmitted, with the highest rates observed with severe anemia (26% vs 19% for mild/none). Readmissions were not significantly different after multivariable adjustment (overall P = .216); however, in those receiving postoperative intensive care, severe anemia was associated with increased readmission rates (hazard ratio [HR], 1.72; 95% confidence interval [CI], 1.09-2.71; reference mild/none]. Posthospitalization RBC transfusion rates were highest with severe anemia (25% vs 10% for mild/none; adjusted HR, 2.2; 95% CI, 1.5-3.3; P < .001). There were no significant differences in composite stroke/myocardial infarction, or mortality. RBC transfusion volumes did not modify anemia-outcome relationships.

CONCLUSION

Hospital discharge hemoglobin values for transfused surgical patients were not associated with hospital readmission rates except for those receiving postoperative intensive care. Further evaluation is warranted to understand downstream consequences of postsurgical anemia.