Organizational Contributors to the Variation in Red Blood Cell Transfusion Practices in Cardiac Surgery: Survey Results From the State of Michigan

Nonclinical factors affecting intraoperative red blood cell transfusion: a systematic review

PURPOSE

There is significant variability in intraoperative red blood cell (RBC) transfusion practice. We aimed to use the theoretical domains framework (TDF) to categorize nonclinical and behavioural factors driving intraoperative RBC transfusion practice in a systematic review of the literature.

SOURCE

We searched electronic databases from inception until August 2021 to identify studies evaluating nonclinical factors affecting intraoperative RBC transfusion. Using the Mixed Methods Appraisal Tool, we assessed the quality of included studies and identified relevant nonclinical factors, which were coded into TDF domains by two independent reviewers using NVivo (Lumivero, QSR International, Burlington, MA, USA). We identified common themes within domains and sorted domains based on the frequency of reported factors.

PRINCIPAL FINDINGS

Our systematic review identified 18 studies: nine retrospective cohort studies, six cross-sectional surveys, and three before-and-after studies. Factors related to the social influences, behavioural regulation, environmental context/resources, and beliefs about consequences domains of the TDF were the most reported factors. Key factors underlying the observed variability in transfusion practice included the social effects of peers, patients, and institutional culture on decision-making (social influences), and characteristics of the practice environment including case volume, geographic location, and case start time (environmental context/resources). Studies reported variable beliefs about the consequences of both intraoperative transfusion and anemia (beliefs about consequences). Provider- and institutional-level audits, educational sessions, and increased communication between surgeons/anesthesiologists were identified as strategies to optimize intraoperative transfusion decision-making (behavioural regulation).

CONCLUSION

Our systematic review has synthesized the literature on nonclinical and behavioural factors impacting intraoperative transfusion decision-making, categorized using the TDF. These findings can inform evidence-based interventions to reduce intraoperative RBC transfusion variability.

STUDY REGISTRATION

Open Science Framework ( https://osf.io/pm8zs/?view_only=166299ed28964804b9360c429b1218c1 ; first posted, 3 August 2022).

Patient-, Clinician-, and Institution-level Variation in Inotrope Use for Cardiac Surgery: A Multicenter Observational Analysis

BACKGROUND

Conflicting evidence exists regarding the risks and benefits of inotropic therapies during cardiac surgery, and the extent of variation in clinical practice remains understudied. Therefore, the authors sought to quantify patient-, anesthesiologist-, and hospital-related contributions to variation in inotrope use.

METHODS

In this observational study, nonemergent adult cardiac surgeries using cardiopulmonary bypass were reviewed across a multicenter cohort of academic and community hospitals from 2014 to 2019. Patients who were moribund, receiving mechanical circulatory support, or receiving preoperative or home inotropes were excluded. The primary outcome was an inotrope infusion (epinephrine, dobutamine, milrinone, dopamine) administered for greater than 60 consecutive min intraoperatively or ongoing upon transport from the operating room. Institution-, clinician-, and patient-level variance components were studied.

RESULTS

Among 51,085 cases across 611 attending anesthesiologists and 29 hospitals, 27,033 (52.9%) cases received at least one intraoperative inotrope, including 21,796 (42.7%) epinephrine, 6,360 (12.4%) milrinone, 2,000 (3.9%) dobutamine, and 602 (1.2%) dopamine (non-mutually exclusive). Variation in inotrope use was 22.6% attributable to the institution, 6.8% attributable to the primary attending anesthesiologist, and 70.6% attributable to the patient. The adjusted median odds ratio for the same patient receiving inotropes was 1.73 between 2 randomly selected clinicians and 3.55 between 2 randomly selected institutions. Factors most strongly associated with increased likelihood of inotrope use were institutional medical school affiliation (adjusted odds ratio, 6.2; 95% CI, 1.39 to 27.8), heart failure (adjusted odds ratio, 2.60; 95% CI, 2.46 to 2.76), pulmonary circulation disorder (adjusted odds ratio, 1.72; 95% CI, 1.58 to 1.87), loop diuretic home medication (adjusted odds ratio, 1.55; 95% CI, 1.42 to 1.69), Black race (adjusted odds ratio, 1.49; 95% CI, 1.32 to 1.68), and digoxin home medication (adjusted odds ratio, 1.48; 95% CI, 1.18 to 1.86).

CONCLUSIONS

Variation in inotrope use during cardiac surgery is attributable to the institution and to the clinician, in addition to the patient. Variation across institutions and clinicians suggests a need for future quantitative and qualitative research to understand variation in inotrope use affecting outcomes and develop evidence-based, patient-centered inotrope therapies.

EDITOR’S PERSPECTIVE

Risk and Safety Perceptions Contribute to Transfusion Decisions in Coronary Artery Bypass Grafting

Variability persists in intraoperative red blood cell (RBC) transfusion rates, despite evidence supporting associated adverse sequelae. We evaluated whether beliefs concerning transfusion risk and safety are independently associated with the inclination to transfuse. We surveyed intraoperative transfusion decision-makers from 33 cardiac surgery programs in Michigan. The primary outcome was a provider's reported inclination to transfuse (via a six-point Likert Scale) averaged across 10 clinical vignettes based on Class IIA or IIB blood management guideline recommendations. Survey questions assessed hematocrit threshold for transfusion ("hematocrit trigger"), demographic and practice characteristics, years and case-volume of practice, knowledge of transfusion guidelines, and provider attitude regarding perceived risk and safety of blood transfusions. Linear regression models were used to estimate the effect of these variables on transfusion inclination. Mixed effect models were used to quantify the variation attributed to provider specialties and hematocrit triggers. The mean inclination to transfuse was 3.2 (might NOT transfuse) on the survey Likert scale (SD: .86) across vignettes among 202/413 (48.9%) returned surveys. Hematocrit triggers ranged from 15% to 30% (average: 20.4%; SE: .18%). The inclination to transfuse in situations with weak-to-moderate evidence for supporting transfusion was associated with a provider's hematocrit trigger (p < .01) and specialty. Providers believing in the safety of transfusions were significantly more likely to transfuse. Provider specialty and belief in transfusion safety were significantly associated with a provider's hematocrit trigger and likelihood for transfusion. Our findings suggest that blood management interventions should target these previously unaccounted for blood transfusion determinants.

Number and Type of Blood Products are Negatively Associated With Outcomes Following Cardiac Surgery

BACKGROUND

The association between blood transfusion and adverse outcome is documented in cardiac surgery. However, the incremental significance of each unit transfused, whether red blood cell (RBC) or non-RBC, is uncertain. This study examined the relationship of patient outcomes with type and number of blood product units transfused.

METHODS

Statewide data from adult cardiac surgery patients were included (N=24,082). Relationship with blood transfusion was assessed for morbidity and 30-day mortality using total number of RBC and non-RBC units transfused, specific type of non-RBC units, and different combinations of transfusion (only RBC, only non-RBC, RBC+non-RBC). Multivariable logistic regressions examined these associations.

RESULTS

Median age was 66 years (30% female) with 51% of patients transfused (31%-66% across hospitals). Risk-adjusted analyses found each blood product unit associated with 9%, 7%, and 4% greater odds for 30-day mortality, major morbidity, and minor morbidity (all P<0.001). Odds for 30-day mortality were 13% greater with each RBC unit (P<0.001) and 6% greater for each non-RBC unit (P<0.001). Each unit of fresh frozen plasma (P<0.001) and platelets (P<0.001) increased odds for 30-day mortality, but no effect for cryoprecipitate (P=0.725). Odds for 30-day mortality were lower for non-RBC only (OR=0.52, P=0.030) and greater for RBC+non-RBC (OR=2.98, P<0.001) compared to RBC only transfusion.

CONCLUSIONS

Independent of center variability on transfusion methods, each additional unit transfused was associated with increased odds for complications, with RBC transfusion carrying greater risk compared to non-RBC. Comprehensive evidence-based clinical approaches and coordination are needed to guide each blood transfusion event following cardiac surgery.

Determinants of hospital variability in perioperative red blood cell transfusions during coronary artery bypass graft surgery

OBJECTIVE

To identify to what extent distinguishing patient and procedural characteristics can explain center-level transfusion variation during coronary artery bypass grafting surgery.

METHODS

Observational cohort study using the Perfusion Measures and Outcomes Registry from 43 adult cardiac surgical programs from July 1, 2011, to July 1, 2017. Iterative multilevel logistic regression models were constructed using patient demographic characteristics, preoperative risk factors, and intraoperative conservation strategies to progressively explain center-level transfusion variation.

RESULTS

Of the 22,272 adult patients undergoing isolated coronary artery bypass surgery using cardiopulmonary bypass, 7241 (32.5%) received at least 1 U allogeneic red blood cells (range, 10.9%-59.9%). When compared with patients who were not transfused, patients who received at least 1 U red blood cells were older (68 vs 64 years; P < .001), were women (41.5% vs 15.9%; P < .001), and had a lower body surface area (1.93 m² vs 2.07 m²; P < .001), respectively. Among the models explaining center-level transfusion variability, the intraclass correlation coefficients were 0.07 for model 1 (random intercepts), 0.12 for model 2 (patient factors), 0.14 for model 3 (intraoperative factors), and 0.11 for model 4 (combined). The coefficient of variation for center-level transfusion rates were 0.31, 0.29, 0.40, and 0.30 for models 1 through 4, respectively. The majority of center-level variation could not be explained through models containing both patient and intraoperative factors.

CONCLUSIONS

The results suggest that variation in center-level red blood cells transfusion cannot be explained by patient and procedural factors alone. Investigating organizational culture and programmatic infrastructure may be necessary to better understand variation in transfusion practices.

Evaluation for Perioperative Blood Transfusion during Major Abdominal Procedures in a Pediatric Population: A Retrospective Observation Cohort Study

Objectives

The purpose of this study was to examine modifiable factors and their impact on perioperative blood transfusion for pediatric patients with major abdominal procedures.

Methods

This is a retrospective review of 1,506 patients who underwent major abdominal surgical procedures in a tertiary medical center from January 2008 to June 2018. Clinical data about blood administration including triggers and targets for intra- or postoperative transfusion were collected and analyzed. The inappropriate transfusion (transfusion > 8.0 g/dL of hemoglobin [Hb] trigger) and overtrans-fusion criteria (target transfusion > 10.0 g/dL or > 2 g/dL of target minus trigger level) were applied to examine the intraoperative factors with the intraoperative transfusion practice. Perioperative morbidity was further assessed based on the inappropriate transfusion and overtransfusion status.

Results

Intraoperative transfusion was used in 468 (31.1%) of the 1,506 patients included in the study. Among them, 212 (45.3%) intraoperative transfusion episodes were classified as inappropriate, and 135 cases (28.8%) were confirmed as overtransfusion. On univariate analysis, inappropriate transfusions were observed more commonly among patients with younger age (p < 0.001) and who underwent hepatic resection (p < 0.001) or intestinal resection (p < 0.001). Overtransfusion was also associated with elevated trigger of 8.0 g/dL Hb (p = 0.006) and younger age (p = 0.003). No perioperative complications were associated with inappropriate transfusions and overtransfusion under multivariate analysis.

Conclusions

Overtransfusion was common in hepatic resection and younger age, but to definitely prove this hypothesis, a prospective randomized trial needs to be performed.