[Predictive value of norepinephrine equivalence score on the 28-day death risk in patients with sepsis: a retrospective cohort study].

Objective: To elucidate the predictive value of norepinephrine equivalence (NEE) score on the 28-day death risk in patients with sepsis and provide evidence for its application in the diagnosis and treatment of sepsis and septic shock.

Methods: A retrospective cohort study was conducted based on the data of patients with sepsis from Medical Information Mart for Intensive Care-IV 2.2 (MIMIC-IV 2.2). The patients who received vasoactive agents within 6 hours after the diagnosis of sepsis or septic shock were enrolled, and they were divided into survival and non-survival groups based on their 28-day outcomes. The baseline characteristics, vital signs, and treatment data were collected. Multivariate Cox regression analysis was performed to identify factors influencing the 28-day death risk. Receiver operator characteristic curve (ROC curve) was drawn to analyze the predictive value of various parameters on the 28-day death risk of septic patients. Kaplan-Meier survival curve was used to evaluate cumulative survival rate in patients classified by different quantitative parameters based on the cut-off values obtained from ROC curve analysis.

Results: A total of 7 744 patients who met the Sepsis-3 diagnostic criteria and received vasopressor treatment within 6 hours post-diagnosis were enrolled, of which 5 997 cases survived and 1 747 died, with the 28-day mortality of 22.6%. Significant differences were observed between the two groups regarding age, gender, height, body weight, race, type of intensive care unit (ICU), acute physiology and chronic health evaluation II (APACHE II) score, sequential organ failure assessment (SOFA) score, Charlson comorbidity index (CCI) score, underlying comorbidities, and vital signs. Compared with the survival group, the non-survival group had poorer blood routine, liver and kidney function, coagulation function, blood gas analysis and other indicators. Multivariate Cox regression analysis revealed that age > 65 years old [hazard ratio (HR) = 0.892, 95% confidence interval (95%CI) was 0.801-0.994, P = 0.039] and male (HR = 0.735, 95%CI was 0.669-0.808, P < 0.001) were protective factors for 28-day death in patients with sepsis, and NEE score (HR = 1.040, 95%CI was 1.021-1.060, P < 0.001), shock index (HR = 1.840, 95%CI was 1.675-2.022, P < 0.001), APACHE II score (HR = 1.076, 95%CI was 1.069-1.083, P < 0.001), SOFA score (HR = 1.035, 95%CI was 1.015-1.056, P < 0.001), and CCI score (HR = 1.135, 95%CI was 1.115-1.155, P < 0.001) were independent risk factors for 28-day death in septic patients. ROC curve analysis showed that the area under the ROC curve (AUC) of NEE score for predicting the 28-day death risk of septic patients was 0.743 (95%CI was 0.730-0.756), which was comparable to the predictive value of APACHE II score (AUC = 0.742, 95%CI was 0.729-0.755) and ratio of mean arterial pressure (MAP)/NEE score (MAP/NEE; AUC = 0.738, 95%CI was 0.725-0.751, both P > 0.05), and better than SOFA score (AUC = 0.609, 95%CI was 0.594-0.624), CCI score (AUC = 0.658, 95%CI was 0.644-0.673), shock index (AUC = 0.613, 95%CI was 0.597-0.629) and ratio of diastolic blood pressure (DBP)/NEE score (DBP/NEE; AUC = 0.735, 95%CI was 0.721-0.748, all P < 0.05). According to the cut-off values of APACHE II and NEE scores obtained from ROC curve analysis, the patients were stratified for Kaplan-Meier survival curve analysis, and the results showed that the 28-day cumulative survival rate in the septic patients with an APACHE II score ≤ 22.5 was significantly higher than that in those with an APACHE II > 22.5 (Log-Rank test: χ² = 848.600, P < 0.001), and the 28-day cumulative survival rate in the septic patients with an NEE score ≤0.120 was significantly higher than that in those with an NEE score > 0.120 (Log-Rank test: χ² = 832.449, P < 0.001).

Conclusions: NEE score is an independent risk factor for 28-day death in septic patients who received vasoactive treatment within 6 hours of diagnosis and possesses significant predictive value. It can be used for severity stratification in sepsis management.