Higher Preoperative Red Blood Cell Distribution Width Increases the Risk of Myocardial Injury After Noncardiac Surgery in Advanced-Age Patients: A Retrospective Cohort Study

Background: Myocardial injury after noncardiac surgery (MINS) has been associated with worse outcomes. The aim of our study was to investigate the relationship between higher red blood cell distribution width (RDW) and postoperative 30-day MINS among advanced-age patients. Methods: This was a retrospective observational study including advanced-age patients (≥ 65 years old) who underwent noncardiac surgery between January 2017 and August 2019 at the First Medical Center of the Chinese People's Liberation Army General Hospital. Patients were divided into two groups according to the cutoff value identified the lowest risk using Restricted Cubic Splines (RCS) model. The primary outcome was the incidence of MINS within 30 days after surgery. The relationship between RDW and MINS was investigated by univariable and multi-variable logistic regression analysis. Propensity score (PS) analysis, including propensity score matching (PSM) and inverse probability treatment weighting (IPTW), as well as subgroup analysis were also conducted to identify the effect of RDW. Results: The result of the RCS analysis showed that the risk of MINS in advanced-age patients increases when the baseline RDW is > 12.8%. In the univariate analysis, baseline RDW > 12.8% was a risk factor for postoperative MINS [odds ratio (OR)=2.11; 95% confidence interval (CI): 1.83– 2.44; p< 0.001]. After adjustment for all possible components, there was also a high risk of MINS for patients with elevated RDW [Adjusted OR (aOR)=1.43; 95% CI: 1.27– 1.61; p< 0.001). The relationship remained after PS analysis (aOR=1.24; 95% CI: 1.04– 1.47; p=0.016 in PSM; aOR=1.23; 95% CI: 1.05– 1.44; p=0.012 in IPTW, respectively). Significant differences between two groups were established in the incidence rate of postoperative cardiac complications and mortality. Conclusion: Elevated preoperative RDW is significantly associated with an increased risk of MINS within postoperative 30 days. Keywords: myocardial injury after noncardiac surgery, red blood cell distribution width, advanced-age patients