The Influence of Preoperative Anaemia on Postoperative Outcomes in First Time Elective Isolated Aortic Valve Replacement Surgery in the Prince Charles Hospital: A Ten-Year Review

Abstract

Y. Ranawaka , C. Villanueva , B. Pearse , S. Gabriel , J. McGree , L. Nair , H. Thompson , D. Wall , P. Tesar 1 Cardiac Surgery Research Unit, Cardiac Surgery Program, The Prince Charles Hospital, Brisbane, Australia School of Mathematical Sciences, Queensland University of Technology, Brisbane, Australia Corresponding author. Introduction: Advancing age in the first world countries has led to an increased number of elderly patients requiring cardiovascular interventions including cardiac surgery. The elderly population have more chronic diseases and the number and proportion of patients with multiple comorbidities is growing. It is therefore common to find previously undiagnosed anaemia in the elective surgical patient cohort. The prevalence of anaemia increases with age with 11% of males and 10.2% of females over the age of 65 being anaemic. It has been previously described that preoperative anaemia increases the risk of in-hospital death, 30 day mortality, blood transfusion, stroke, infection and kidney failure, among others. This study aims to assess the relationship between preoperative anaemia and postoperative clinical outcomes in elective isolated aortic valve replacement (AVR) patients from The Prince Charles Hospital (TPCH). Methods: Between January 2002 and December 2011, clinical and outcomes data were collected in 815 isolated AVR surgeries from the Cardiac Surgical Registry at TPCH. Patients were partitioned into two groups (anaemic group: HCT < 0.34, n = 55; baseline group: HCT 0.34, n = 760). Characteristics between the anaemic and baseline groups were compared using regression techniques to investigate the relationships between preoperative anaemia and postoperative clinical outcomes. Preoperative risk factors and postoperative morbidities were analysed to determine the end points of ventilation time, length of ICU stay, length of hospital stay and red blood cell (RBC) transfusion. Results: Fifty-five patients of the 815 were found to be anaemic preoperatively. Preoperative anaemia was associated with increased hospital length of stay (p 0.001), increase in initial stay in ICU (p 0.001) and required prolonged ventilation (p 0.001). Anaemic patients were also shown to have a higher probability of requiring reopening for bleeding (p = 0.0708) and postoperative RBC transfusion (p 0.001). Discussion: This study shows that preoperative anaemia in 1st time elective AVR impacts on RBC transfusion, length of hospital and ICU stay as well as ventilation hours and returns to theatre for bleeding. These factors are associated with an increased cost for the health system and impacts on patients’ recovery. Our results will be used as a baseline to compare the postoperative outcomes of patients’ in the future after correction of anaemia preoperatively.