Early Diagnostic Markers and Risk Stratification in Sepsis: Prognostic Value of Neutrophil-to-Lymphocyte Ratio, Platelets, and the Carmeli Score

Abstract

Background/Objectives: Sepsis is characterized by a dysregulated host response to infection, where immune-inflammatory and thrombo-inflammation drive organ dysfunction. Early recognition of high-risk patients is essential. In addition, the increasing prevalence of multidrug-resistant (MDR) pathogens complicates therapeutic strategies, as delays in appropriate antimicrobial therapy are strongly associated with poor outcomes. Methods: We conducted a retrospective, single-center cohort study including 120 critically ill patients fulfilling Sepsis-3 criteria. Demographic, clinical, and laboratory data were collected at intensive care unit (ICU) admission, 48 h, and 72 h. The neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR) were calculated from complete blood counts. At the same time, the Carmeli score was used as a surrogate for MDR infection risk. Prognostic accuracy was assessed using ROC curve analysis and multivariable logistic regression. Results: Persistently elevated NLR at 72 h and a delayed decline in platelet counts were associated with higher mortality. NLR at 72 h showed good predictive accuracy (AUC = 0.765; 95% CI 0.668–0.863), and the combination of APACHE II and NLR improved prognostic performance (AUC = 0.827). Importantly, the Carmeli score, reflecting MDR infection risk, was an independent predictor of outcome, linking antimicrobial resistance risk with sepsis prognosis. Conclusions: Dynamic immune-inflammatory biomarkers (NLR, platelets), when integrated with MDR risk assessment through the Carmeli score, provide a simple and cost-effective strategy for early prognostic stratification in sepsis. This combined approach may help facilitate early therapeutic decisions and patient care triage.