Pre-operative Red Cell Distribution Width (RDW) as an easy and low-cost predictor of mortality after arterial vascular surgeries

Background Perioperative complications are a major cause of death worldwide, and patients submitted to arterial vascular surgeries face a very high-risk of cardiac complications. Risk-stratification in this setting remains challenging, as existing algorithms often underestimate risk. Red cell distribution width (RDW), a widely available hematological parameter, has emerged as a potential biomarker associated with adverse outcomes across various clinical conditions. However, its prognostic value in vascular surgery patients remains uncertain. Purpose: To assess the association between RDW and 30-day mortality and cardiovascular complications in patients submitted to arterial vascular surgeries. Methods Retrospective cohort that included patients submitted to arterial vascular surgery at a university tertiary referral hospital in Brazil from January 2012 to February 2020. The primary outcome was all-cause mortality assessed 30 days post-surgery. Secondary outcomes included major adverse cardiovascular events (MACE) at 30 days and perioperative myocardial injury / infarction (PMI). RDW was analyzed as a continuous variable and dichotomized at 16%. Cox proportional hazards models, Kaplan-Meier survival analysis, and receiver operating characteristic (ROC) curve analysis were used to assess RDW’s predictive ability. Fine and Gray’s competing-risk analysis was performed to evaluate the association of RDW and MACE. All events were adjudicated by independent cardiologists. Results A total of 1,425 patients undergoing 1,565 arterial vascular surgeries were included. A high burden of comorbidities was observed (Figure 1). Elevated RDW (≥16%) was independently associated with 30-day mortality (adjusted hazard ratio [aHR] 1.60, 95% CI 1.1 - 2.3; p=0.013). RDW alone had moderate predictive ability at ROC analysis (AUC = 0.62) but improved risk stratification when added to the Vascular Surgery Group Cardiac Risk Index (VSG-CRI) score (Figure 2). Adding RDW, anemia, non-elective surgery to the VSG-CRI score provided a net reclassification improvement of 23% (NRI 0.23, 95% CI 0.14 – 0.33). However, elevated RDW was not independently associated with MACE at 30 days (aHR 1.01, 95% CI 0.97 – 1.06; p=0.55) or PMI (aHR 1.02, 95% CI 0.96 – 1.09; p=0.49). Conclusions In patients undergoing arterial vascular surgery, RDW ≥ 16% was an independent predictor of 30-day mortality but did not predict MACE or PMI. Furthermore, RDW provided incremental value when added to existing perioperative risk algorithms. Given its wide availability and low cost, RDW may serve as a valuable adjunct in perioperative risk assessment.Table 1. ROC curves