A point score system for predicting the likelihood of blood transfusion after hip or knee arthroplasty

Mapping the landscape of machine learning models used for predicting transfusions in surgical procedures: a scoping review

Massive transfusion of blood products poses challenges in determining the need for transfusion and the appropriate volume of blood products. This review explores the use of machine learning (ML) models to predict transfusion risk during surgical procedure, focusing on the methodology, variables, and software employed to predict transfusion. This scoping review investigates the development and current state of machine learning models for predicting transfusion risk during surgical procedure, aiming to inform physicians about the field's progress and potential directions.The review was conducted using the databases Cochrane, Embase, and PubMed. The search included keywords related to blood transfusion, statistical models, and surgical procedures. Peer-reviewed articles were included, while literature reviews, case reports, and non-human studies were excluded.A total of 40 studies met the inclusion criteria. The most frequently studied biological variables included haemoglobin, platelet count, international normalized ratio (INR), activated partial thromboplastin time (aPTT), fibrinogen, creatinine, white blood cells, and albumin. Clinical variables of importance included age, sex, surgery type, blood pressure, weight, surgery duration, american society of anesthesiology (ASA) status, blood loss, and body mass index (BMI). The software employed varied, with Python, R, SPSS, and SAS being the most commonly used. Logistic regression was the predominant methodology used in 20 studies.Our scoping review highlights the need for improved reporting and transparency in methodology, variables, and software used. Future research should focus on providing detailed descriptions and open access to codes of respective models, promoting reproducibility, and enhancing the clinical relevance of transfusion risk prediction models.

Preoperative prediction of Bleeding Independently associated with Mortality after noncardiac Surgery (BIMS): an international prospective cohort study

BACKGROUND

Diagnostic criteria for Bleeding Independently associated with Mortality after noncardiac Surgery (BIMS) have been defined as bleeding that leads to a postoperative haemoglobin <70 g L^-1, leads to blood transfusion, or is judged to be the direct cause of death. Preoperative prediction guides for BIMS can facilitate informed consent and planning of perioperative care.

METHODS

In a prospective cohort study of 16 079 participants aged ≥45 yr having inpatient noncardiac surgery at 12 academic hospitals in eight countries between 2007 and 2011, 17.3% (2782) experienced BIMS. An electronic risk calculator for BIMS was developed and internally validated by logistic regression with bootstrapping, and further simplified to a risk index. Decision curve analysis assessed the potential utility of each prediction guide compared with a strategy of identifying risk of BIMS based on preoperative haemoglobin <120 g L^-1.

RESULTS

With information about the type of surgery, preoperative haemoglobin, age, sex, functional status, kidney function, history of high-risk coronary artery disease, and active cancer, the risk calculator accurately predicted BIMS (bias-corrected C-statistic, 0.84; 95% confidence interval, 0.837-0.852). A simplified index based on preoperative haemoglobin <120 g L^-1, open surgery, and high-risk surgery also predicted BIMS, but less accurately (C-statistic, 0.787; 95% confidence interval, 0.779-0.796). Both prediction guides could improve decision making compared with knowledge of haemoglobin <120 g L^-1 alone.

CONCLUSIONS

BIMS, defined as bleeding that leads to a postoperative haemoglobin <70 g L^-1, leads to blood transfusion, or that is judged to be the direct cause of death, can be predicted by a simple risk index before surgery.

CLINICAL TRIAL REGISTRATION

NCT00512109.

Total knee Arthroplasty: risk factors for allogeneic blood transfusions in the South Asian population

BACKGROUND

Total knee arthroplasty (TKA) is the recommended treatment for end-stage knee osteoarthritis. Considering the various risks associated with intra and postoperative blood transfusions, better understanding is required with respect to the risk factors contributing to a greater possibility of blood transfusion during or after surgery. Although literature highlights several such factors, our study is among the first to identify these risk factors in the South Asian population which differs from other populations in several ways.

METHODS

The study consists of a review of 658 patients undergoing TKA from 2005 to 2015. Data was obtained from patient medical records and was analysed using logistic regression analysis. The relationship between each predictor and the outcome variable was calculated as an Odds ratio (OR), the threshold of significance for which was p = 0.25 and p = 0.05 for univariate and multivariable analysis respectively.

RESULTS

The mean age of the patient population was 63 years (78% female), 25% of whom received one or more blood transfusions. Multivariable analysis revealed 5 significant independent predictors for increased risk of blood transfusions including bilateral knee surgery (OR:5.51), preoperative anemia (OR:4.15), higher ASA (American Society of Anaesthesiologists) status (3-4) (OR:1.92), female sex (OR:3.44) and BMI (Body mass index) ≤30 (OR:1.79) while increasing co-morbidities and age (>60) were found to be insignificant.

CONCLUSIONS

The factors identified for the South Asian population are largely similar to those for other populations. Identification of high risk patients will permit the application of an international multipronged approach which not only targets the modifiable risk factors but also the decision making process and blood management protocols in order to minimize the transfusion associated risks for a patient undergoing a TKA.

Predicting Perioperative Transfusion in Elective Hip and Knee Arthroplasty: A Validated Predictive Model

BACKGROUND

Preoperative anemia is a significant predictor of perioperative erythrocyte transfusion in elective arthroplasty patients. However, interactions with other patient and procedure characteristics predicting transfusion requirements have not been well studied.

METHODS

Patients undergoing elective primary total hip arthroplasty or total knee arthroplasty at a tertiary hospital in Adelaide, South Australia, Australia, from January 2010 to June 2014 were used to identify preoperative predictors of perioperative transfusion. A logistic regression model was developed and externally validated with an independent data set from three other hospitals in Adelaide.

RESULTS

Altogether, 737 adult patients in the derivation group and 653 patients in the validation group were included. Binary logistic regression modeling identified preoperative hemoglobin (odds ratio, 0.51; 95% CI, 0.43 to 0.59; P < 0.001 for each 1 g/dl increase), total hip arthroplasty (odds ratio, 3.56; 95% CI, 2.39 to 5.30; P < 0.001), and females 65 yr of age and older (odds ratio, 3.37; 95% CI, 1.88 to 6.04; P = 0.01) as predictors of transfusion in the derivation cohort.

CONCLUSIONS

Using a combination of patient-specific preoperative variables, this validated model can predict transfusion in patients undergoing elective hip and knee arthroplasty. The model may also help to identify patients whose need for transfusion may be decreased through preoperative hemoglobin optimization.

Bleeding impacting mortality after noncardiac surgery: a protocol to establish diagnostic criteria, estimate prognostic importance, and develop and validate a prediction guide in an international prospective cohort study

INTRODUCTION

Various definitions of bleeding have been used in perioperative studies without systematic assessment of the diagnostic criteria for their independent association with outcomes important to patients. Our proposed definition of bleeding impacting mortality after noncardiac surgery (BIMS) is bleeding that is independently associated with death during or within 30 days after noncardiac surgery. We describe our analysis plan to sequentially 1) establish the diagnostic criteria for BIMS, 2) estimate the independent contribution of BIMS to 30-day mortality and 3) develop and internally validate a clinical prediction guide to estimate patient-specific risk of BIMS.

METHODS

In the Vascular Events In Noncardiac Surgery Patients Cohort Evaluation (VISION) study, we prospectively collected bleeding data for 16 079 patients aged 45 years or more who had noncardiac inpatient surgery between 2007 and 2011 at 12 centres in 8 countries across 5 continents. We will include bleeding features independently associated with 30-day mortality in the diagnostic criteria for BIMS. Candidate features will include the need for reoperation due to bleeding, the number of units of erythrocytes transfused, the lowest postoperative hemoglobin concentration, and the absolute and relative decrements in hemoglobin concentration from the preoperative value. We will then estimate the incidence of BIMS and its independent association with 30-day mortality. Last, we will construct and internally validate a clinical prediction guide for BIMS.

INTERPRETATION

This study will address an important gap in our knowledge about perioperative bleeding, with implications for the 200 million patients who undergo noncardiac surgery globally every year. Trial registration: ClinicalTrials.gov, no NCT00512109.

Preoperative haemoglobin cut-off values for the prediction of post-operative transfusion in total knee arthroplasty

PURPOSE

The purpose of this study is to determine preoperative haemoglobin cut-off values that could accurately predict post-operative transfusion outcome in patients undergoing primary unilateral total knee arthroplasty (TKA). This will allow surgeons to provide selective preoperative type and screen to only patients at high risk of transfusion.

METHODS

A total of 1457 patients diagnosed with osteoarthritis and underwent primary unilateral TKA between January 2012 and December 2014 were retrospectively reviewed. Logistic regression analyses were applied to identify factors that could predict transfusion outcome.

RESULTS

A total of 37 patients (2.5 %) were transfused postoperatively. Univariate analysis revealed preoperative haemoglobin (p < 0.001), age (p < 0.001), preoperative haematocrit (p < 0.001), and preoperative creatinine (p < 0.001) to be significant predictors. In the multivariate analysis with patients dichotomised at 70 years of age, preoperative haemoglobin remained significant with adjusted odds ratio of 0.33. Receiver operating characteristic curve identified the preoperative haemoglobin cut-off values to be 12.4 g/dL (AUC = 0.86, sensitivity = 87.5 %, specificity = 77.2 %) and 12.1 g/dL (AUC = 0.85, sensitivity = 69.2 %, specificity = 87.1 %) for age above and below 70, respectively.

CONCLUSIONS

The authors recommend preoperative haemoglobin cut-off values of 12.4 g/dL for age above 70 and 12.1 g/dL for age below 70 to be used to predict post-operative transfusion requirements in TKA. To maximise the utilisation of blood resources, the authors recommend that only patients with haemoglobin level below the cut-off should receive routine preoperative type and screen before TKA.

LEVEL OF EVIDENCE

IV.

Comparison of Blood Loss between Neutral Drainage with Tranexamic Acid and Negative Pressure Drainage without Tranexamic Acid Following Primary Total Knee Arthroplasty

Purpose

There are many methods to reduce massive bleeding during total knee arthroplasty (TKA). In our study, tranexamic acid and neutral drainage were used to decrease total blood loss.

Materials and Methods

The study was performed on 97 TKA patients from March 2012 to January 2013. In the study group, tranexamic acid was administered and neutral drainage was applied. The study group had group I (unilateral, n=29) and group III (bilateral, n=17). The control group had group II (unilateral, n=35) and group IV (bilateral, n=16).

Results

In group I, the drainage volume on the 1st and 2nd postoperative days and the total drainage decreased with statistical significance (p<0.05). Between group III and group IV, group III had less drainage volume. In group III, the drainage volume on the 1st postoperative day and total drainage volume decreased statistically significantly (p<0.05). Between groups I and II, total blood loss showed no statistically significant difference, whereas between groups III and IV, the value was significantly different.

Conclusions

Intravenous administration of tranexamic acid with neutral drainage for 3 postoperative hours is a recommendable method because it can be helpful in reducing total blood loss in bilateral TKA.

Effect of Body Mass Index on Blood Transfusion in Total Hip and Knee Arthroplasty

Perioperative blood management remains a challenge during total hip arthroplasty (THA) and total knee arthroplasty (TKA). The purpose of this study was to systematically examine the relationship between body mass index (BMI) and perioperative blood transfusion during THA and TKA while attempting to resolve conflicting results in previously published studies. The authors retrospectively evaluated 2399 patients, 896 of whom underwent THA and 1503 of whom underwent TKA. Various outcome variables were assessed for their relationship to BMI, which was stratified using the World Health Organization classification scheme (normal, <25 kg/m(2); overweight, 25-30 kg/m(2); obese, >30 kg/m(2)). Among patients undergoing THA, transfusion rates were 34.8%, 27.6%, and 21.9% for normal, overweight, and obese patients, respectively (P=.002). Among patients undergoing TKA, transfusion rates were 17.3%, 11.4%, and 8.3% for normal, overweight, and obese patients, respectively (P=.002). Patients with an elevated BMI have decreased rates of blood transfusion following both THA and TKA. This same cohort also loses a significantly decreased percentage of estimated blood volume. No trends were identified for a relationship between BMI and deep venous thrombosis, pulmonary embolism, myocardial infarction, discharge location, length of stay, 30-day readmission rate, and preoperative hemoglobin level. Elevated BMI was significantly associated with increased estimated blood loss in patients undergoing THA and those undergoing TKA. There was a statistically significant trend toward increased deep surgical-site infection in patients undergoing THA (P=.043). Patients with increased BMI have lower rates of blood transfusion and lose a significantly smaller percentage of estimated blood volume following THA and TKA. [Orthopedics.2016; 39(5):e844-e849.].

Predicting Blood Loss in Total Knee and Hip Arthroplasty

Marked blood loss during lower extremity total joint arthroplasties may lead to higher rates of transfusion, which may negatively affect surgical outcomes and yield greater complication rates. It is therefore ideal to identify factors that may increase the likelihood of blood loss, so they can be modified. From this review, it can be concluded that preoperative anemia, older age, multiple comorbidities, increased operative time, and use of postoperative anticoagulation may lead to higher blood loss and transfusion rates, although the influence of other factors remains controversial.

Development and validation of a predictive score for perioperative transfusion in patients with hepatocellular carcinoma undergoing liver resection

BACKGROUND

Liver resection is a major surgery requiring perioperative blood transfusion. Predicting the need for blood transfusion for patients undergoing liver resection is of great importance. The present study aimed to develop and validate a model for predicting transfusion requirement in HBV-related hepatocellular carcinoma patients undergoing liver resection.

METHODS

A total of 1543 consecutive liver resections were included in the study. Randomly selected sample set of 1080 cases (70% of the study cohort) were used to develop a predictive score for transfusion requirement and the remaining 30% (n=463) was used to validate the score. Based on the preoperative and predictable intraoperative parameters, logistic regression was used to identify risk factors and to create an integer score for the prediction of transfusion requirement.

RESULTS

Extrahepatic procedure, major liver resection, hemoglobin level and platelets count were identified as independent predictors for transfusion requirement by logistic regression analysis. A score system integrating these 4 factors was stratified into three groups which could predict the risk of transfusion, with a rate of 11.4%, 24.7% and 57.4% for low, moderate and high risk, respectively. The prediction model appeared accurate with good discriminatory abilities, generating an area under the receiver operating characteristic curve of 0.736 in the development set and 0.709 in the validation set.

CONCLUSIONS

We have developed and validated an integer-based risk score to predict perioperative transfusion for patients undergoing liver resection in a high-volume surgical center. This score allows identifying patients at a high risk and may alter transfusion practices.

Efficacy of preoperative autologous blood donation for elective posterior lumbar spinal surgery

STUDY DESIGN

Retrospective review.

OBJECTIVE

Evaluate the transfusion patterns associated with preoperative autologous blood donation (PABD) during posterior lumbar spinal surgery.

SUMMARY OF BACKGROUND DATA

There is a paucity of evidence in the literature examining the utility of PABD in elective adult lumbar spinal surgery.

METHODS

Medical records of 541 patients treated for spinal stenosis between January 1997 and February 2000 were reviewed. Patients were divided into donors (PABD; n = 413) and nondonors (non PABD [NPABD]; n = 128).

RESULTS

Average preoperative hemoglobin (Hb) in the NPABD group was 0.62 units more than in the PABD group (95% confidence interval [CI] = 0.30-0.94). For PABD patients, there was a negative correlation (-0.3) between preoperative Hb and number of units donated. PABD patients who donated 1 and 2 units of blood were, respectively, 7.5 and 9 times more likely to be transfused within the first 24 hours than NPABD patients. NPABD patients were 25 times more likely to need a transfusion of allogeneic blood than PABD patients who donated at least 2 units of blood. Autologous donation was an independent predictor of perioperative blood loss (P < 0.05). Patients who donated at least 2 units of blood lost approximately 1.3 units of Hb more than NPABD patients. The odds of wastage for a PABD patient who had a decompression with noninstrumented fusion were 8.64 times that of a PABD patient who had a decompression with instrumented fusion.

CONCLUSION

Autologous blood donation induced preoperative anemia and resulted in a lower transfusion threshold than allogeneic blood usage. In addition, we found that autologous donation significantly increased blood loss in the preoperative period as measured by Hb lost. Usage of autologous blood was significantly more efficient in patients who underwent instrumented fusion than in patients with less complex surgery.

Warfarin management in patients on continuous anticoagulation therapy undergoing total knee replacement

We evaluated the safety and efficacy of total knee replacement in patients receiving continuous warfarin therapy.

We identified 24 consecutive patients receiving long-term warfarin therapy who underwent total knee replacement between 2006 and 2008 and compared them with a group of age- and gender-matched patients not on long-term anticoagulation. Primary observations were changes in haemoglobin, transfusion rates and complications. Secondary observations were fluctuations in the international normalised ratio (INR) and post-operative range of movement.

There was no significant difference between the two groups in pre- or post-operative haemoglobin, incidence of transfusion or incidence of post-operative complications. There were no surgical delays due to a high INR level. The mean change in INR during the peri-operative phase was minimal (mean 0.4; sd 0.7). There was no significant difference in the range of movement between the two groups after day two post-operatively.

Current American College of Chest Physicians guidelines recommend bridging therapy for high-risk patients receiving oral anticoagulation and undergoing major orthopaedic procedures. We have shown that a safe alternative is to continue the steady-state warfarin peri-operatively in patients on long-term anticoagulation requiring total knee replacement.

Drivers of transfusion decision making and quality of the evidence in orthopedic surgery: a systematic review of the literature

Reasons for variation in transfusion practice in orthopedic surgery are not well understood. This systematic review identified and appraised the quality of the literature in this area to assess the impact of factors associated with the use of allogeneic red blood cell (RBC) transfusion in orthopedic procedures. MEDLINE and EMBASE databases were searched for relevant English language publications. Articles containing a range of MeSH and text terms regarding "blood transfusion," "predictors," and "multiple logistic regression" were retrieved. Articles that focused on patients undergoing orthopedic procedures and that met prespecified inclusion criteria were appraised in terms of potential bias and the appropriateness of statistical approach. A total of 3641 citations were retrieved, and 29 met the inclusion criteria for the review. Articles reported on a range of orthopedic procedures including total hip arthroplasty; total knee arthroplasty, total shoulder arthroplasty, and spinal surgery. Most studies were conducted in the United States (n = 12) or Canada (n = 5). Study quality was moderate; 50% or more of the quality criteria were assessed in 15 articles. Particular areas of concern were the lack of prospective studies, lack of clarity in defining the time interval between risk factor assessment and transfusion outcome, and lack of model validation. A narrative synthesis found that 2 factors consistently influenced the use of RBC transfusion-decreased hemoglobin (n = 25) and increased patient age (n = 18). Increased surgical complexity (n = 12), low body weight (n = 9), presence of additional comorbidities (n = 9), and female sex (n = 7) were also important factors. The general quality of the studies in the field is weak. However, low hemoglobin and increasing age were consistently identified as independent risk factors for RBC transfusion in orthopedic practice. Additional or alternative analytical approaches are required to obtain a more comprehensive, holistic understanding of the decision to transfuse RBCs to patients undergoing orthopedic surgery.

The effects of applying adhesion prevention gel on the range of motion and pain after TKA

A mixed solution of sodium hyaluronate and sodium carboxymethylcellulose (HA/CMC) has been shown to be effective for decreasing postoperative adhesions in various kinds of surgeries. We evaluated the clinical efficacy and safety of HA/CMC gel on the early postoperative range of motion and pain relief after total knee arthroplasty (TKA). Thirty one patients who underwent bilateral TKA as a single-stage procedure for primary osteoarthritis were included in the study. At the completion of surgery, among both knees, the HA/CMC gel was applied to one knee (the HA/CMC group) and HA/CMC gel was not applied to the other knee (the control group). The primary outcome measure was the early assessment of range of motion and the secondary outcome measures were the VAS pain scores and the number of complications in each group. Periarticular application of HA/CMC gel was safe without causing any wound problems or infection. However, local application of HA/CMC gel neither increased the range of motion nor reduced the pain during the early postoperative period of TKA.

Association of allogeneic red-blood cell transfusion with surgeon case-volume

BACKGROUND

Surgeon case-volume predicts a variety of patient outcomes. We hypothesize that surgeon case-volume predicts RBC transfusion across different surgical procedures.

METHODS

We performed a cohort study of 372,670 in-patient surgical cases in the 52 non-federal hospitals in Maryland between 2004 and 2005. The main outcome measure was relative risk of receiving a transfusion.

RESULTS

Overall, 13.9% of patients received a transfusion. Patients seen by the highest case-volume surgeons (>161 cases/y) were more likely to receive a transfusion (16% versus 11%, P < 0.01) compared with middle case-volume surgeons (89-161 cases/y). After adjusting for confounders, the highest case-volume patients were still at increased risk of transfusion [relative risk (RR) 1.10, 1.07-1.14]. This result was true across many surgery types.

CONCLUSIONS

Surgeon case-volume is independently associated with the likelihood of RBC transfusion across a broad range of surgical procedures. Future efforts should be directed towards studying and standardization of transfusion practices.

Prospective evaluation of the clinical prediction of electrodiagnostic results in carpal tunnel syndrome

OBJECTIVE

To develop a unique clinical prediction point-score system for the diagnosis of carpal tunnel syndrome (CTS) and to prospectively evaluate this clinical rule to determine its ability to predict electrodiagnostic results.

DESIGN

Retrospective case control to develop the clinical point-score system and then prospective diagnostic study with blind comparison to electrodiagnostic results.

SETTING

Community-based electrodiagnostic laboratory.

PATIENTS

A total of 348 subjects referred to the electrodiagnostic laboratory with a clinical suspicion of CTS to develop the clinical point-score system and then a different population of 278 subjects referred to the electrodiagnostic laboratory over a 1-year period with a clinical suspicion of CTS to prospectively evaluate the ability of the clinical rule to predict electrodiagnostic results.

MAIN OUTCOME MEASURES

Clinical point-score system results were compared with the electrodiagnostic results for CTS, which served as the primary outcome measure.

RESULTS

A "weighted" point-score system was developed from 9 clinical variables including: gender, duration of symptoms, presence of wrist pain (negative predictor), presence of neck pain (negative predictor), nocturnal symptoms, presence of thenar atrophy, abductor pollicis brevis weakness, median sensory symptoms, and results of pinprick sensation examination. The prospective evaluation indicated that the clinical point-score rule, overall, performed moderately in predicting electrodiagnostic results (receiver operator characteristic curve = 0.80). The clinical point score was most predictive in a small subset of subjects with very high scores. However, in most subjects, the clinical point score could not accurately predict electrodiagnostic outcome in CTS, particularly in subjects with middle to low clinical point scores.

CONCLUSIONS

The developed clinical point-score rule was most predictive in subjects with high point score; however, the majority of the referrals to the electrodiagnostic laboratory indicated that the electrodiagnostic studies provided additional, independent information beyond what could be obtained by the clinical point score.

Relative risk factors for requirement of blood transfusion after total hip arthroplasty

One thousand thirty-five total hip arthroplasty (THA) cases were retrospectively reviewed, and the number and type (autologous and allogenic) of postoperative units of blood transfused were analyzed with respect to pre-, intra-, and postoperative variables. The most significant and consistent predictors of a blood transfusion after THA were advanced age and the use of low-molecular-weight heparin for deep venous thrombosis prophylaxis. Our recommendations for predonation are 1 unit for THA patients younger than 75 years if hemoglobin is 130 g/dL or greater and 2 units or a combination of 1 unit of predonated blood and 1 unit of directed or banked blood for THA patients older than 75 years.

A risk score for predicting perioperative blood transfusion in liver surgery

BACKGROUND

It would be desirable to predict which patients are most likely to benefit from preoperative autologous blood donation. This aim of this study was to develop a point scoring system for predicting the need for blood transfusion in liver surgery.

METHODS

The medical records of 480 consecutive patients who underwent hepatic resection were analysed. The data set was split randomly into a derivation set of two-thirds and a validation set of one-third. Univariable analysis was carried out to determine the association between clinicopathological factors and blood transfusion. Significant variables were entered into a multiple logistic regression model, and a transfusion risk score (TRS) was developed. The accuracy of the system was validated by calculating the area under the receiver-operator characteristic (ROC) curve.

RESULTS

Factors associated with blood transfusion in multivariable analysis included preoperative haemoglobin concentration below 12.5 g/dl, largest tumour more than 4 cm, need for exposure of the vena cava, need for an associated procedure, and cirrhosis. Each variable was assigned one point, and the total score was compared with the transfusion status of each patient in the validation set. The TRS accurately predicted the likelihood of blood transfusion. In the validation set the area under the ROC curve was 0.89.

CONCLUSION

Use of the TRS could lead to substantial saving by improving the cost-effectiveness of the autologous blood donation programme.

A restrictive use of both autologous donation and recombinant human erythropoietin is an efficient policy for primary total hip or knee arthroplasty

A limitation of preoperative autologous blood donation (PABD) in nonanemics and the use of recombinant human erythropoietin (EPO) in anemics (baseline hematocrit [Hct] < or = 39%) could be an efficient approach of the cost-benefit ratio of transfusion during primary total hip (THA) or knee (TKA) arthroplasties. We evaluated the consequences on transfusion rates and costs of two different applications of a transfusion policy based on personal requirements during primary THA or TKA. This quality assurance observational study compared two prospective successive time periods; each included successive patients treated by the same medical team and standardized care. In Study 1 (n = 182), PABD was indicated if there were insufficient estimated red blood cell reserve and a life expectancy > or = 10 yr, no use of EPO, and identical criteria for any transfusion. Because this policy led to a 50% allogeneic transfusion rate when baseline Hct < or = 37% and autologous blood wastage in the nonanemics (baseline Hct > 39%), 2 refinements were introduced in Study 2 (n = 708): EPO without PABD when baseline Hct < or = 37%, and life expectancy > or = 10 yr, and avoidance of PABD in nonanemics. This novel care induced a marked decrease in transfusion rates (respectively, from 41% to 7%, P < 0.0002, in nonanemics; from 58% to 27%, P < 0.003, in anemics; and from 43% to 12%, P < 0.0001, overall), with no change in allogeneic transfusion (10%) and discharge Hct, and a 39% financial savings. This saving effect is a result of the suppression of PABD in nonanemics, who represent 75% of this surgical population. Although erythropoietin is expensive, it can be used with cost savings in selected patients because the overall cost of transfusion is reduced.

Risks associated with blood transfusion after total knee arthroplasty

A retrospective study of 1,402 patients who underwent primary total knee arthroplasty (TKA) (1,194 unilateral, 208 bilateral) was performed. The strongest predictors for allogenic transfusion after surgery were advancing age (P<.001), low preoperative hemoglobin (P<.001), and the use of low-molecular-weight heparin postoperatively (P<.01). Pre-donation of 1 unit of autologous blood before TKA decreased the allogenic transfusion rate from a baseline of 38% to 11%, whereas pre-donating 2 units lowered the rate of breakthrough transfusion of allogenic blood to 7%. A patient with a preoperative hemoglobin >150 g/L or who is younger than age 65 with a preoperative hemoglobin >130 g/L may not benefit from pre-donation, and a high rate of wastage may result.

Effects of blood transfusion on clinical and functional outcomes in patients with hip fracture

BACKGROUND

Anemia and transfusion are common among elderly patients requiring surgery. The effects of transfusion on morbidity and mortality are controversial. The influence of transfusion on risk-adjusted mortality, readmissions, and functional mobility was examined.

STUDY DESIGN AND METHODS

A consecutive cohort of 551 patients undergoing surgery for hip fracture at four hospitals was prospectively studied. Outcomes were death, readmission, and functional independence measure-locomotion scores within 60 days of discharge. The trigger Hb level was defined as the lowest value before the first postoperative transfusion. Multivariate analyses adjusted for a validated, hip-fracture-specific risk model and predictors of transfusion.

RESULTS

Overall, 54.4 percent of patients received transfusions after surgery. Seventy-two percent of patients with a lowest postoperative Hb level of less than 10.0 g per dL received transfusions compared to 19.6 percent of those whose lowest measurement was at least 10.0 g per dL (p < 0.0001). In the 60 days after discharge, 3.8 percent of patients died and 16.9 percent were readmitted. Transfusion was associated with lower risk-adjusted odds of readmission (OR, 0.54; 95% CI, 0.30-0.97), but it did not influence mortality or mobility functioning. In subgroups analyses, the benefit of transfusion on readmission rates appeared to be concentrated among patients with a trigger Hb level of less than 10.0 g per dL. For patients with a trigger Hb level of at least 10.0 g per dL, transfusion did not affect risk-adjusted rates of death or readmission, but was associated with better risk-adjusted functional mobility scores (p < 0.01).

CONCLUSIONS

Postoperative transfusion reduced the risk of readmission but did not decrease mortality or improve mobility. Randomized controlled trials of different transfusion strategies will be needed to clarify the true benefits and risks of transfusion in surgical patients.

Review of the clinical practice literature on patient characteristics associated with perioperative allogeneic red blood cell transfusion

There is evidence to suggest that there exists considerable variation in red blood cell (RBC) transfusion practices, especially in the surgical specialties. This is in large part related to difficulties in defining specific transfusion threshold criteria, given that there is no minimum acceptable hemoglobin threshold concentration and there is variability in assigning importance to patient factors. The purpose of this study is to identify patient-related factors that might be associated with the need for allogeneic RBC transfusion in surgical patients. We systematically identified, selected, and reviewed all observational or interventional studies describing patient-specific or related variables associated with the need for allogeneic RBC transfusion in the surgical patient population. We also evaluated the methodological characteristics of the individual studies. Sixty-two studies met our inclusion criteria and were analyzed for this review. Most of these studies were conducted in patients undergoing cardiac surgery (n = 30) and orthopedic surgery (n = 16). Decreased preoperative red cell reserve was most frequently associated with RBC transfusions, being identified as a significant variable in 46 studies. The other factors commonly associated with transfusion were advancing age (n = 28), female gender (n = 21), and small body size (n = 14). Only 2 studies attempted to prospectively validate a predictive model for RBC transfusion based on the variables identified. This systematic review shows that preoperative anemia, advancing age, female gender, and small body size are often associated with perioperative allogeneic RBC transfusion. However, the retrospective nature of most of the studies and the small sample sizes make it difficult to formulate a clinically useful prediction rules regarding allogeneic RBC transfusion. Ongoing research in designing large prospective cohort studies evaluating transfusion patterns are needed to further elucidate how patient characteristics impact the transfusion threshold.

Identifying patients for blood conservation strategies

BACKGROUND

Generally, only the type of operation is used to estimate the need for perioperative homologous blood transfusion. This study quantified the extent to which the estimation could be improved if, in addition, simple patient characteristics were taken into account.

METHODS

Retrospective data on 24 509 consecutive adult surgical patients were used to derive and validate three models to predict perioperative homologous transfusion. The first model was a univariable model with type of operation as the only predictor. The second and third models were a full and a simplified multivariable logistic regression model. The performance of the multivariable models was tested in two validation sets: in similar patients who had operations in the same general hospital (internal validation) and in patients who had operations in a university hospital (external validation). The areas under the receiver-operator characteristic (ROC) curve were compared with that found in the derivation set.

RESULTS

There were no important differences in characteristics between the derivation and validation sets. The ROC area of the model including surgery only was 0.92 (99 per cent confidence interval (c.i.) 0.91 to 0.94) and that of the full and simplified multivariable models 0.95 (99 per cent c.i. 0.94 to 0.96) and 0.94 (99 per cent c.i. 0.93 to 0.95) respectively. The latter two were significantly different from the first one. In the external validation set the ROC area of the simplified model was 0.84 (95 per cent c.i. 0.83 to 0.86). Patients who had a preoperative haemoglobin level lower than 13 g/dl and underwent major invasive surgery had the highest risk (43 per cent) of transfusion.

CONCLUSION

A simple algorithm using type of operation and haemoglobin concentration was effective in identifying patients likely to need perioperative homologous blood transfusion.

Preoperative predictors of blood transfusion in colorectal cancer surgery

Transfusion is associated with multiple risks and morbidities. Little is known, however, about preoperative predictors of transfusion in gastrointestinal surgery patients. To identify factors that influence transfusion practices, we analyzed hospital discharge data from colorectal cancer surgery patients in Maryland between 1994 and 2000 (n = 14,052). The primary outcome variable was whether or not patients received a blood product ("Any Transfusion"). Characteristics independently associated with an increased risk of receiving Any Transfusion included: advanced age (>80 yr: OR 2.3; 95% CI 1.9-2.9; 70-79 yr: OR 1.6; 95% CI 1.4-2.0 vs. <60 yr), moderate to severe liver disease (OR 2.5; 95% CI 1.5-4.2), mild liver disease (OR 2.1; 95% CI 1.5-2.9), diabetes with complications (OR 2.1; 95% CI 1.6-2.6), chronic renal disease (OR 2.1; 95% CI 1.4-3.0), female gender (OR 1.3; 95% CI 1.2-1.5), chronic pulmonary disease (COPD) (OR 1.3; 95% CI 1.1-1.4), and metastatic disease (OR 1.2; 95% CI 1.1-1.4). Patients at hospitals with an annual case volume in the highest quartile were at an increased risk for receiving Any Transfusion (OR 2.1; 95% CI 1.3-3.4) and those with surgeons in the highest volume quartile (>12 cases/yr) were at a decreased risk (OR 0.8; 95% CI 0.6-0.99). The association between greater surgeon case volume and low transfusion rates was seen in all but the very high volume hospitals (>74 cases/yr). Blood product transfusion was associated with a 2.5-fold (95% CI 2.1-3.1) increased mortality, 3.7 day (95% CI 2.1-3.1) increase in hospital length of stay, and a 7120 dollars (95% CI 6472 dollars-7769 dollars) increase in total charges compared to patients that did not receive Any Transfusion. This data can be used by providers in discussions with patients regarding the risks for transfusion and in identifying patients in whom strategies to reduce transfusions should be evaluated.

Validation of a clinical prediction rule to reduce preoperative type and screen procedures

BACKGROUND

We have developed a prediction rule for the occurrence of perioperative red blood cell transfusion to help to reduce the number of unnecessary preoperative type and screen procedures. We evaluated the robustness of this prediction rule in patients from another hospital.

METHODS

The rule was retrospectively applied to 1282 consecutive patients ('validation set') who underwent similar surgical procedures to the patients in the derivation study. The outcome was similarly defined as any allogeneic transfusion on the day of surgery or during the first postoperative day. The predictive value of the rule was assessed using a Receiver Operating Characteristic curve (ROC) and compared with the results of the derivation study. Subsequently, the number of correctly predicted transfusions was compared.

RESULTS

The patient characteristics did not differ between the two sets, except for the incidence of transfusion (derivation study: 18%; present study: 8%). In the validation set, the ROC area of the prediction rule was 0.78 (95% confidence intervals [CI]: 0.73-0.82), which was within the CI of the ROC area found in the derivation study (0.75; 95% CI: 0.72-0.79). In total, 35% of the type and screen procedures could be omitted (derivation study: 50%), with 13% missed transfused patients (derivation study: 20%).

CONCLUSIONS

After comparing the results of this validation study with that of the derivation study, the prediction rule was robust and may work in other clinics as well.

Use of the blood transfusion service in total knee replacement arthroplasty. The cost implications

In view of the rising costs of blood transfusion and reports of inappropriate transfusions an audit of the local practice was organised. The aim was to investigate whether blood transfusion in primary unilateral Total Knee replacement Arthroplasty (TKA) operations was being used inappropriately locally, the resultant cost implications and suggest ways of reducing these. A 1-year retrospective survey of blood transfusion practice was conducted for all consecutive elective, primary, unilateral TKA operations at a District-General Hospital. 169 operations were performed and 58 (34%) patients were transfused. A retrospective Haemoglobin concentration (Hb) analysis was performed for all the transfused patients to identify the number of transfusions that satisfied the suggested transfusion criteria of a threshold Hb of 8 g/dl and when indicated, a minimum transfusion of 2 units. Complete transfusion data was available on 49/58 (84%) patients transfused. When applying the above criteria to this sample, the potential annual saving for the department was estimated at approximately 8000 pounds Sterling; only 9 of these patients were deemed to be appropriately transfused.

The reduction of preoperative autologous blood donation for primary total hip or knee arthroplasty: the effect on subsequent transfusion rates

We conducted this quality assurance observational study to examine the effects of a change in policy regarding preoperative autologous blood donation (PABD) and indications for perioperative blood transfusion in patients undergoing primary total hip or knee arthroplasty. Two successive time periods, each including 182 successive patients treated by the same medical team and with standardized anesthesia, were compared. The first study had the following standard transfusion policy: 3 U of PABD collected (n = 119) and liberal autologous transfusion (AT). The second study introduced a specific indication for PABD, on the basis of estimated red blood cell reserve and a life expectancy of more than 10 years; 2 U of PABD was collected (n = 81), and criteria were identical for AT and allogeneic transfusion. We mainly compared the incidence of AT; allogeneic and overall transfusions; the inclusion, admission, and discharge hematocrit values; and the wastage of PABD units. This novel policy increased the number of untransfused patients by a factor of 10 (5.5% vs 56.6%) (P < 0.0001), decreased the number of PABD patients by 30% with a 2.4-fold reduction in AT (30% vs 80%) (P < 0.0001), and did not change allogeneic requirements (13% vs 15%). Although fewer autologous units were collected (172 vs 426), the wastage was higher in Study 2 (46% vs 12%) (P < 0.0001). We conclude that incorporation of patients' individual factors improves the efficiency of transfusion for total hip and total knee arthroplasty surgeries.

IMPLICATIONS

We compared two transfusion policies for primary total hip or knee arthroplasties: first, a standard preoperative autologous donation with a liberal autologous transfusion policy; and second, a more restrictive indication for autologous donation that was based on patients' individual factors, with identical criteria for autologous and allogeneic transfusion. We found that this change of policy reduced autologous donation and transfusion with no increase in allogeneic transfusion.

Predictors of transfusion for spinal surgery in Maryland, 1997 to 2000

BACKGROUND

The purpose of this study was to identify preoperative patient, hospital, and surgeon characteristics associated with transfusion for spinal surgery.

STUDY DESIGN AND METHODS

Discharge data were obtained from 39 Maryland hospitals for adult patients (n = 3988) who had a primary procedure code for spinal surgery between July 1997 through June 2000, and with these codes, surgeons and hospitals were characterized by annual patient volume. Outcome variables included any allogeneic transfusion, any transfusion, RBCs, autologous blood, FFP, or platelet transfusion. Logistic regression was used for univariate and multivariate analyses.

RESULTS

Characteristics independently associated with an increased risk of receiving any allogeneic transfusion (n = 786) included age >54 (OR, 1.6; 95% CI, 1.3-2.1), age >66 (OR, 2.7; 95% CI, 2.0-3.5), female sex (OR, 1.6; 95% CI, 1.2-2.0), diabetes with chronic complications (OR, 2.5; 95% CI, 1.3-4.9), and metastatic tumor (OR, 4.9; 95% CI, 2.3-10.5), emergency room admission (OR, 2.3; 95% CI, 1.4-3.8), and greater hospital volume (OR, 4.0; 95% CI, 1.8-8.6). Characteristics independently associated with increased autologous transfusions (n = 574) included white race (OR, 1.7; 95% CI, 1.2-2.4), female sex (OR, 1.4; 95% CI, 1.1-1.8), and greater surgeon volume (OR, 3.5; 95% CI, 1.4-9.1).

DISCUSSION

This information can be used to provide informed risk-benefit discussions with patients regarding the risk for blood transfusion as well as to target high-risk patients and institutions for interventions to reduce the risk of exposure to blood components.

Effectiveness of a protocol to improve transfusion practice in knee replacement surgery

BACKGROUND AND OBJECTIVES

The available guidelines on red cell transfusion are not clearly defined and therefore have had only a modest impact on transfusion practice. The aims of this study were to assess the rate of compliance with a transfusion algorithm and its effect on transfusion practice.

MATERIALS AND METHODS

A prospective observational study was carried out on 101 patients who underwent primary elective total knee replacement surgery.

RESULTS

Only 30% of the patients were transfused. An overall compliance rate of 77% was achieved with the transfusion algorithm.

CONCLUSION

A transfusion algorithm, together with staff education, is effective in reducing both the number of patients transfused and inappropriate transfusions.

Transfusion practice in elective orthopaedic surgery

. The transfusion requirements of 2233 patients who underwent total hip or knee joint arthroplasty procedures at nine Canadian hospitals during 1995-1996 were evaluated. Although 64% of patients were eligible for participation in an autologous blood donation (ABD) programme, only 8% predonated blood. Patients who were eligible for ABD were younger (62 years vs. 70 years) and had fewer medical illnesses (18% vs. 44%) than those who did not predonate. The rate of allogeneic transfusion was 9.0% (95% confidence interval 4.9-13.1%) in patients who predonated as compared with 24.1% (95% confidence interval 22.2-25.9%) in those who did not. Risk factors for the occurrence of an allogeneic transfusion were type of procedure (primary or revision hip arthroplasty), lower baseline haemoglobin, lower body weight, older age and presence of rheumatoid arthritis (P < 0.001). Only patients without risk factors were predicted to have a less than 10% risk of receiving an allogeneic transfusion. Use of preventive strategies was minimal. Two models designed to predict the occurrence of an allogeneic transfusion were evaluated. If allogeneic transfusion rates are to be reduced, eligible patients should be encouraged to participate in ABD programmes. For patients who are ineligible, other preventative strategies should be introduced.

Autologous transfusion and other approaches to reduce allogeneic blood exposure

When used as the sole source of transfused blood, the principal advantage of autologous blood transfusion is the avoidance of transmission of infectious agents and the avoidance of the purported adverse immunomodulatory effects of allogeneic transfusion. In the 1990s, however, the risks of transfusion-transmitted diseases have been greatly reduced, and estimates of the cost-effectiveness of pre-operative autologous blood donations now vary between 2470 dollars and 3,400,000 dollars per quality-adjusted year of life saved, depending on assumptions about the existence and magnitude of any adverse immunomodulatory effects of allogeneic transfusion. There is a paucity of randomized controlled trials evaluating the clinical outcomes and the cost-effectiveness of autologous transfusion procedures, and this situation is unlikely to change in the near future because of the difficulties in conducting such trials. This chapter reviews the available evidence on the efficacy, safety and cost-effectiveness of the three common autologous transfusion procedures, that is, pre-operative autologous blood donation, acute normovolaemic haemodilution, and intra-operative and post-operative blood recovery.

Efficacy of preoperative autologous blood donation: analysis of blood loss and transfusion practice in total hip replacement

STUDY OBJECTIVE

To determine the frequency of allogeneic transfusion for total hip replacement (THR) surgery and to examine the efficacy of preoperative autologous blood donation (PABD) under specified, standardized blood transfusion guidelines.

DESIGN

Prospective, nonrandomized study.

SETTING

University medical center.

PATIENTS

All ASA physical status I, II, III, and IV patients undergoing single, primary, THR surgery from April 1998 to March 1999.

INTERVENTIONS

All patients received standardized transfusion and anticoagulation therapy. Demographic, blood loss, and transfusion data were collected and compared between all patients participating in PABD (donors) and patients not participating in PABD (nondonors). Overall allogeneic blood exposure was established. Since most anemic patients could not participate in PABD, allogeneic transfusion frequency was also examined in a subset of nonanemic patients (hemoglobin > or =12 g/dL) who were potentially able to participate in PABD.

MEASUREMENTS AND MAIN RESULTS

n = 231 patients, 142 donors and 89 nondonors. Mean estimated blood volume (EBV) of donors was 4991 +/- 1042 mL versus nondonors 4631 +/- 1108 mL (p < 0. 01). ASA physical status I-II/III-IV among donors was 118/24 versus nondonors 61/28 (p < 0.01). Overall allogeneic blood exposure was 22% (51/231). Allogeneic transfusion frequency for all donors was 15% (22/142) versus nondonors 33% (29/89) (p < 0.05). Among nonanemic patients, donor versus nondonor EBV and ASA physical status I-II/III-IV were 5074 +/- 1019 mL versus 4743 +/- 1172 mL and 107/20 versus 48/15 (p = NS); allogeneic transfusion frequency reduced to 13% (16/127) versus 17% (11/63) (p = NS), respectively.

CONCLUSIONS

Allogeneic blood exposure was >10% despite the use of PABD. The efficacy of PABD has been obscured by the fact that donors of autologous blood tend to be larger and healthier than nondonors. After exclusion of anemic patients, autologous donors and nondonors were clinically comparable and the difference in allogeneic blood exposure was not statistically significant. PABD offers only a modest, if any, benefit for THR surgery.

Blood conservation in patients undergoing non-cardiac surgery

Concerns about the safety, inventory, and cost of allogeneic blood have led to a renewed interest in blood conservation. Autologous blood collection techniques, including preoperative autologous donation, acute normovolemic hemodilution, and perioperative blood recovery are routinely used as alternatives to allogeneic transfusion. In the future, these techniques may be combined with pharmacological strategies, such as presurgical erythropoietin therapy or red cell substitutes, to reduce further the need for allogeneic blood.

A study of an educational intervention to decrease inappropriate preoperative autologous blood donation: its effectiveness and the effect on subsequent transfusion rates in elective hysterectomy

BACKGROUND

Decreasing the overcollection of preoperative autologous blood is difficult to achieve. The purpose of this study was to determine whether an educational intervention designed to outline the risks of preoperative autologous collection can decrease such donations and, if so, to determine how this decrease will affect subsequent transfusion rates.

STUDY DESIGN AND METHODS

An educational intervention consisting of a didactic presentation to the Department of Gynecology staff about the risks and benefits of autologous blood was implemented. Written material with similar information was given to patients. Subsequently, the percentage of patients donating autologous blood, the number of autologous units donated, and the rates of transfusion in patients eligible for autologous donation who were admitted for elective abdominal or vaginal hysterectomy were measured. These rates were compared to those in similar patients admitted in the 2 years before the educational intervention.

RESULTS

After an educational intervention, the proportion of patients donating autologous blood decreased from 53 percent to 26 percent (p<0.01), and the number of units collected per patient decreased from 0.86 to 0.31 (p<0.01); this resulted in a savings of 80 autologous donations per year. Despite no difference in estimated blood loss (p = 0.46), the overall transfusion rate decreased from 10 percent to 3.7 percent (p = 0.03), while the allogeneic transfusion rate demonstrated no significant change (1.1% vs. 2.2%; p = 0.40).

CONCLUSIONS

Unnecessary preoperative autologous donations by elective hysterectomy patients can be decreased by educating physicians and patients about the risks of preoperative autologous blood donation. Decreasing such unnecessary donations can decrease the subsequent autologous transfusion rate, with its attendant risks, without increasing the risk of allogeneic transfusion.

An analysis of blood management in patients having a total hip or knee arthroplasty

Three hundred and thirty orthopaedic surgeons in the United States participated in a study of transfusion requirements associated with total joint arthroplasty. A total of 9482 patients (3920 patients who had a total hip replacement and 5562 patients who had a total knee replacement) were evaluated prospectively from September 1996 through June 1997. Of those patients, 4409 (46 percent [57 percent of the patients who had a hip replacement and 39 percent of the patients who had a knee replacement]) had a blood transfusion. Two thousand eight hundred and ninety patients (66 percent) received autologous blood, and 1519 patients (34 percent) received allogenic blood. Ordered logistic regression analysis showed the most important predictors of the transfusion of allogenic blood to be a low baseline hemoglobin level and a lack of predonated autologous blood. Preoperative donation of autologous blood decreases the risk of transfusion of allogenic blood; however, inefficiencies in the procedures for obtaining autologous blood were identified. Sixty-one percent (5741) of the patients had predonated blood for autologous transfusion, but 4464 (45 percent) of the 9920 units of the predonated autologous blood were not used. Primary procedures and revision total knee arthroplasty were associated with the greatest number of wasted autologous units. Of the 5741 patients who had predonated blood, 503 (9 percent) needed a transfusion of allogenic blood. The frequency of allogenic blood transfusion varied with respect to the type of operative procedure (revision total hip arthroplasty and bilateral total knee arthroplasty were associated with the highest prevalence of such transfusions) and with a baseline hemoglobin level of 130 grams per liter or less. Transfusion of allogenic blood was also associated with infection (p < or = 0.001), fluid overload (p < or = 0.001), and increased duration of hospitalization (p < or = 0.01). These latter findings warrant further evaluation in controlled studies.

Prospective validation of a point score system for predicting blood transfusion following hip or knee replacement

BACKGROUND

The purpose of this study was to validate a previously published point score system for predicting the likelihood of a postoperative blood transfusion following hip or knee replacement.

STUDY DESIGN AND METHODS

Data were collected prospectively on 460 sequential patients undergoing elective hip and knee replacement at two academic hospitals. Blood transfusion frequency was determined for patients in each of the four risk strata, as defined by the point score system. The accuracy of the system was validated by calculating the area under the receiver operating characteristic (ROC) curve for each site. Data were then combined and inappropriate blood transfusions were eliminated, by using the American College of Physicians guidelines. The frequencies of blood transfusion within each strata were recalculated along with an ROC curve.

RESULTS

The point score system accurately predicted the likelihood of blood transfusion at both hospitals, despite marked differences in overall transfusion frequencies. The calculated areas under the ROC curves were 0.78 and 0.79 for the two sites. The point score system also proved valid when only appropriate blood transfusions were considered, with a calculated area under the ROC curve of 0.74.

CONCLUSION

The point score system can accurately predict the likelihood of postoperative blood transfusion following hip or knee replacement. Such a system can be used to target high-risk patients for preoperative autologous blood donation.

The transfusion audit as a tool to improve transfusion practice: a critical appraisal

Transfusion audits have a long history and they are required by many regulatory agencies. These audits have been touted as effective in reducing unnecessary transfusions as evidenced by many published articles on the subject. Most of these studies, however, have one or more flaws in their design including the use of historical controls, disregard of the Hawthorne effect, use of multiple interventions, and publication bias. Studies differ in the baseline rate of inappropriate transfusions and have different methods of measuring these rates. There is also little data on how long the effect of implementing a transfusion audit system may last. Transfusion audits appear most successful when there is a high baseline rate of inappropriate transfusions and interventions other than the audit itself are performed. Individual institutions should critically evaluate whether or not their current system of transfusion audits is useful.