The correlation between the hemoglobin-to-red cell distribution width ratio and all-cause mortality in patients with malignant tumors and sepsis: A retrospective cohort study using the MIMIC-Ⅳ database

Objective The aim of the study was to investigate the correlation between the hemoglobin-to-red cell distribution width ratio(HRR) and all-cause mortality in patients with malignant tumors and sepsis.Methods All patients who met the inclusion criteria of the Medical Information Mart for Intensive Care(MIMIC)-Ⅳ were selected and divided into four groups according to the quartile range of HRR distribution. Kaplan-Meier(K-M) analysis was used to plot the 28-day survival curve, and the log-rank test was used to compare the prognosis in each HRR group. A Cox proportional hazards regression model was used to evaluate the prognosis of HRR as both a continuous and categorical variable, and a restricted cubic spline was used to study the effect of HRR, as a continuous variable, on the mortality in patients with malignant tumors and sepsis. Interaction and subgroup analyses were performed to evaluate the consistency of correlations.Results A total of 3926 patients were included in the study, including 934 patients in the HRR ≤ 4.97 group, 988 patients in the 4.97 < HRR ≤ 6.26 group, 1005 patients in the 6.26 < HRR ≤ 7.84 group, and 999 patients in the HRR ≥ 7.84 group. According to the K-M analysis, the 28-day survival rate was the lowest in the HRR ≤ 4.97 group(59.53%), and there were significant differences in survival rates among different HRR levels(P < 0.001). The Cox proportional hazards regression model found that after adjusting for various potential confounding factors, HRR was negatively correlated with 28-day and 365-day mortality, and the risk of death in the HRR ≥ 7.84 group was significantly lower than that in the HRR ≤ 4.97 group(P = 0.030 and P = 0.008, respectively). The restricted cubic spline plot revealed a linear and negative relationship between the HRR and the 28-day and 365-day mortality rates. Subgroup analysis revealed an interaction between HRR, blood urea nitrogen, and SAPS II scores(P = 0.010 and P = 0.048, respectively).Conclusion Low HRR is an independent risk factor for all-cause mortality in patients with malignant tumors and sepsis and could be used as a prognostic indicator for these patients.