Developing a new sepsis screening tool based on lymphocyte count, international normalized ratio and procalcitonin (LIP score)

Abstract

Exploring an effective sepsis screening tool that can be widely implemented is important for improving the prognosis of sepsis worldwide. This study aimed to develop a new simple screening tool for sepsis (LIP scoring system) that includes the peripheral blood lymphocyte count, international normalized ratio, and procalcitonin level. In a single-center, prospective, observational study, 444 acute sepsis inpatients and 444 nonsepsis inpatients were ultimately included based on the Sepsis-3 and exclusion criteria. The differences in the Lym, INR, PCT level and other clinical biomarkers were compared between the two groups. Univariable and multivariable logistic regression analyses and receiver operating characteristic analysis were used to establish a LIP screening tool for sepsis with a combination of biomarkers. The Kappa and McNemar tests were used to evaluate the differences between the LIP screening results (LIP score ≥ 3) and Sepsis-3 criteria (SOFA score ≥ 2). Logistic regression analysis showed that the lymphocyte count, INR, PCT level, platelets, neutrophil/lymphocyte ratio (NLR) and prothrombin time (PT) were independent risk factors for the development of sepsis. The ROC analysis showed that the lymphocyte count, INR, and PCT level had high area under the ROC curve values (AUROC (95% CI): Lym 0.84 (0.810-0.860), INR 0.921 (0.902-0.938), PCT level 0.928 (0.909-0.944)). The LIP tool had satisfactory screening efficacy for sepsis (sensitivity, 92.8%; specificity, 94.1%), and a LIP score equal to or greater than 3 points had good agreement with Sepsis-3 criteria in the diagnosis of sepsis (Kappa = 0862 in the Kappa test and P = 0.512 in the McNemar test). The LIP tool has satisfactory sensitivity and specificity for sepsis screening, and it can be used for rapid screening of patients with sepsis in outpatient and emergency departments or in economically underdeveloped areas with limited resources.

Figure 1

Flowchart of study participant enrollment. (A) The judgment process for sepsis in patients with suspected infection. SOFA ≥ 2 means that the SOFA score increases by 2 or more points compared to the base value. (B) Sepsis and nonsepsis patient cohort enrollment process.

Figure 2

The performance of individual biomarkers in the screening of sepsis was evaluated by ROC analysis. (A): All patients; (B): Nonpulmonary infection group; (C): Pulmonary infection group. Lym lymphocyte count; INR international normalized ratio; PCT Procalcitonin; NLR Neutrophil-to-lymphocyte ratio; PLT Platelet count; PT Prothrombin time.

Figure 3

The combined diagnostic efficacy of the biomarkers for sepsis as evaluated by ROC curves. (A): All patients; (B): Nonpulmonary infection group; (C): Pulmonary infection group. Lym Lymphocyte count; INR International normalized ratio; PCT Procalcitonin.

Figure 4

Performance of the LIP score in sepsis screening compared with the APACHE II score and SAPS II. The AUROCs of the SAPS II, APACHE II score, and LIP score were 0.922 (95% CI, 0.902–0.939), 0.853 (95% CI, 0.828–0.876), and 0.974 (95% CI, 0.961–0.983), respectively. AUROC (95% CI) Area under the receiver operating characteristic curve (95% confidence interval); APACHE II Acute Physiology and Chronic Health Evaluation II; SAPS II Simplified Acute Physiology Score II.