Clinical value of the red blood cell distribution width to albumin ratio in the assessment of prognosis in critically ill patients with sepsis: a retrospective analysis

Abstract

Background: Red blood cell (RBC) distribution width (RDW) to albumin ratio is a novel biomarker and its prognostic effect on critically ill patients with sepsis has not been extensively investigated. The objective of this study was to identify the prognostic value of the RDW to albumin ratio in these patients.

Methods: Data were extracted from the Medical Information Mart for Intensive Care III (MIMIC-III) database. A Cox proportional hazards model and restricted cubic spline model were used to determine the association of RDW to albumin ratio with mortality. Receiver operating characteristic (ROC) curves and Kaplan-Meier survival curves were applied, and the area under the curve (AUC) was used to compare the predictive value.

Results: A total of 3,969 eligible patients were enrolled. The median RDW to albumin ratio was significantly higher in non-survivors than in survivors at 30 and 90 days. Patients were divided into groups according to the RDW to albumin ratio, and the risk of 30- and 90-day mortality markedly increased in the group with a higher ratio. The relationship between the RDW to albumin ratio as a continuous variable and 30-day mortality also showed an upward trend in the restricted cubic spline. The AUC of the RDW to albumin ratio was 0.633 in discriminating 30-day mortality which was similar to that of the lactate to albumin ratio (AUC =0.617; P=0.133) and higher than that of the neutrophil percentage to albumin ratio (AUC =0.559; P<0.001).

Conclusions: The RDW to albumin ratio is a promising biomarker for assessing the prognosis of critically ill patients with sepsis. Its predictive value in determining mortality was found to be similar to that of the lactate to albumin ratio and superior to that of the neutrophil percentage to albumin ratio.

Keywords: Sepsis; albumin; prognosis; red blood cell distribution width (RDW).

Figure 1

Flowchart of patients enrolled from the MIMIC-III database. ICU, intensive care unit; MIMIC-III, Medical Information Mart for Intensive Care III.

Figure 2

Comparison of RDW to albumin ratio between non-survivors and survivors at 30 and 90 days. The overall median RDW to albumin ratio at both 30 and 90 days in the non-survivor group was significantly higher than that in the survivor group. RDW, red blood cell distribution width; Alb, albumin.

Figure 3

The association between RDW to albumin ratio as a continuous variable and mortality in critically ill patients with sepsis. Crude and adjusted HR and 95% CI for the RDW to albumin ratio in 30- and 90-day mortality. The adjusted confounding factors are shown in model 2 (Table 2), and it is evident that an increased RDW to albumin ratio is associated with the risk of death in patients with sepsis. HR, hazard ratio; CI, confidence interval; RDW, red blood cell distribution width.

Figure 4

Adjusted HR and 95% CI of the RDW to albumin ratio for 30-day mortality subgroup. Confounding factors were adjusted as shown in model 1 (Table 2), and the adjusted HR and 95% CI were calculated and compared to those of the RDW to albumin ratio <4.915 group. RDW, red blood cell distribution width; HR, hazard ratio; CI, confidence interval; COPD, chronic obstructive pulmonary disease.

Figure 5

Prognostic value of indicators for predicting 30-day mortality in patients with sepsis (Table 3). RDW, red blood cell distribution width; AUC, area under the curve.

Figure 6

Kaplan-Meier survival curve at 30 days between the low and high RDW to albumin ratio groups. The 30-day mortality rate in the high RDW to albumin ratio group (≥5.246) was significantly higher than that in the low RDW to albumin ratio group (<5.246) (P for log rank test <0.001). RDW, red blood cell distribution width.