Preoperative Anemia is Associated with Increased Intraoperative Mortality in Patients Undergoing Cardiac Surgery

Prevalence and Comorbidities of Anemia in Hospitalized Adults

BACKGROUND

Anemia, characterized by a decline in hemoglobin levels insufficient to meet the body's physiological demands, poses significant health risks. Its unchecked presence in patients has been medically linked to a surge in mortality and morbidity rates and reduced treatment effectiveness.

OBJECTIVES

This research aims to (1) determine the prevalence of anemia occurrence among adult patients hospitalized at Thumbay University Hospital, (2) highlight the comorbidities accompanying anemic patients, and (3) assess anemia patterns across different age groups, with a focus on young adults.

METHODS

This hospital-centric, observational research analyzed the hematological test results of 437 patients. Participants were classified based on age, gender, hemoglobin concentration at admission, mean corpuscular volume, hospital stay duration, existing conditions and comorbidities at admission, and long-term medications. Anemia was diagnosed if hemoglobin levels were less than 120 g/L in females and under 130 g/L in males.

RESULTS

Among the hospitalized patients, 52.17% exhibited anemia, with females showing a higher prevalence than males. The highest occurrence of anemia was notably among the elderly population, particularly those over 65, while the lowest was found in adults aged between 31 and 40. The majority of cases were attributed to chronic disease-related anemia and infection, with the former being the most common underlying cause.

CONCLUSION

This research provides an assessment of anemia prevalence in a clinical setting, analyzing a substantial cohort of hospitalized adults. The results reveal a high occurrence of anemia, primarily mild or moderate, among patients admitted to internal medicine and long-term care wards. The study's findings can underscore the frequency of anemia in hospital settings. Further exploration is required to understand the heightened prevalence of anemia among young adults.

Analysis of Anemia, Transfusions, and CABG Outcomes in The Society of Thoracic Surgeons National Database

BACKGROUND

This study characterized the association of preoperative anemia and intraoperative red blood cell (RBC) transfusion on outcomes of elective coronary artery bypass grafting (CABG).

METHODS

Data from 53,856 patients who underwent CABG included in The Society of Thoracic Surgeons (STS) Adult Cardiac Database in 2019 were used. The primary outcome was operative mortality. Secondary outcomes were postoperative complications. The association of anemia with outcomes was analyzed with multivariable regression models. The influence of intraoperative RBC transfusion on the effect of preoperative anemia on outcomes was studied using mediation analysis.

RESULTS

Anemia was present in 25% of patients. Anemic patients had a higher STS Predicted Risk of Operative Mortality (1.2% vs 0.7%; P < .001). Anemia was associated with operative mortality (odds ratio [OR], 1.27; 99.5% CI, 1.00-1.61; P = .047), postoperative RBC transfusion (OR, 2.28; 99.5% CI, 2.12-2.44; P < .001), dialysis (OR, 1.58; 99.5% CI, 1.19-2.11; P < .001), and prolonged intensive care unit and hospital length of stay. Intraoperative RBC transfusion largely mediated the effects of anemia on mortality (76%), intensive care unit stay (99%), and hospital stay, but it only partially mediated the association with dialysis (34.9%).

CONCLUSIONS

Preoperative anemia is common in patients who undergo CABG and is associated with increased postoperative risks of mortality, complications, and RBC transfusion. However, most of the effect of anemia on mortality is mediated through intraoperative RBC transfusion.

Preoperative anemia and anemia treatment in cardiac surgery: a systematic review and meta-analysis

PURPOSE

We aimed to conduct a systematic review and meta-analysis to assess the effects of anemia and anemia severity on patient outcomes in cardiac surgery and determine whether preoperative treatments confer postoperative benefit.

SOURCE

We searched four international databases for observational and randomized studies published until 1 October 2022. Study quality was assessed via Newcastle-Ottawa scores and the Cochrane Risk-of-Bias 2 tool and certainty of evidence was rated with the Grading of Recommendations, Assessment, Development and Evaluations approach. We conducted random-effects meta-analyses for our primary outcome of mortality, for secondary outcomes including length of stay (LOS) in the hospital and intensive care unit, and for postsurgical complications. As part of a secondary analysis, we analyzed short-term preoperative anemia treatments and conducted trial sequential analysis of randomized trials to assess the efficacy of these treatment programs.

PRINCIPAL FINDINGS

We included 35 studies (159,025 patients) in our primary meta-analysis. Preoperative anemia was associated with increased mortality (odds ratio [OR], 2.5; 95% confidence interval [CI], 2.2 to 2.9; P < 0.001, high certainty). Study-level meta-regression revealed lower hemoglobin levels and studies with lower proportions of male patients to be associated with increased risk of mortality. Preoperative anemia was also associated with an increase in LOS and postsurgical complications. Our secondary analysis (seven studies, 1,012 patients) revealed short-term preoperative anemia treatments did not significantly reduce mortality (OR, 1.1; 95% CI, 0.65 to 1.9; P = 0.69). Trial sequential analysis suggested that there was insufficient evidence to conclude if treatment programs yield any benefit or harm.

CONCLUSIONS

Preoperative anemia is associated with mortality and morbidity after cardiac surgery. More research is warranted to test the efficacy of current anemia treatment programs.

STUDY REGISTRATION

PROSPERO (CRD42022319431); first submitted 17 April 2023.