Sepsis is a systemic inflammatory response caused by an imbalance of the host immune response to infectious factors, potentially leading to life-threatening organ dysfunction. The application of immature platelet fraction (IPF) to assessing the severity and prognosis of sepsis has been previously analyzed. However, the application of IPF combined with other biomarkers to predict sepsis has been rarely reported.

To explore the predictive value of IPF combined with other biomarkers in the severity and prognosis of sepsis.

A total of 60 sepsis patients admitted to the Department of Critical Care Medicine, Zhongshan Hospital, Fudan University (Xiamen Branch) from November 2020 to November 2022 were retrospectively recruited for analyzing their clinical data. Patients were classified into the severe sepsis group (n=24) and septic shock group (n=36) based on the severity of sepsis. Divided by the Sequential Organ Failure Assessment (SOFA) score, 60 sepsis patients were assigned into the low SOFA group (SOFA score<6 points, n=26) and high SOFA group (SOFA score ≥6 points, n=34). According to the outcome, there were 39 cases in the survival group and 21 cases in the death group. IPF and other blood indicators, including neutrophil to albumin ratio (NAR), platelet to lymphocyte ratio (PLR), neutrophil to lymphocyte ratio (NLR), and lactate to albumin ratio (LAR) were compared. The receiver operating characteristic (ROC) curves of IPF combined with other biomarkers for predicting the severity and prognosis of sepsis were plotted, and the area under the curve (AUC) was calculated.

The proportion of lung diseases, baseline Acute Physiology and Chronic Health Evaluation Ⅱ (APACHE Ⅱ) scores and baseline SOFA scores were significantly higher in the death group compared to those of the survival group (P<0.05). Similarly, the proportion of lung diseases, baseline APACHE II scores and mortality were significantly higher in the high SOFA group compared to those of the low SOFA group (P<0.05). IPF at 48 hours of treatment was significantly higher in the septic shock group than that of the severe sepsis group, which was significantly higher in the high SOFA group compared to that of the low SOFA group, and significantly higher in the death group compared to that of the survival group (P<0.05). Given the significant difference in 48 h IPF between groups, the laboratory indicators at this time point were selected for further research and analysis. The AUC of IPF in predicting septic shock, a high SOFA score and death was 0.70 (95%CI=0.55 to 0.83, cut-off value 3.95%) and 0.72 (95%CI=0.60 to 0.86, cut-off value 7.70%), 0.73 (95%CI=0.58 to 0.89, cut-off value 6.10%), respectively. The AUC of IPF + baseline APACHE Ⅱscore + NLR, and IPF + baseline APACHE Ⅱ score + LAR in predicting a high SOFA score was 0.91 (95%CI=0.84 to 0.98) and 0.93 (95%CI=0.84 to 0.99), respectively. The AUC of IPF + NAR + PLR in predicting the death in sepsis patients was 0.90 (95%CI=0.81 to 0.98) .

IPF combined with different blood indicators can improve the ability to assess the severity and prognosis of sepsis in clinical practice. Specifically, 48 h IPF + baseline APACHE Ⅱ score+48 h NLR and 48 h IPF + baseline APACHE Ⅱscore+48 h LAR have high efficacy in predicting the severity of sepsis; whereas 48 h IPF+NAR+PLR shows a superior efficacy in predicting the prognosis of sepsis.