Study on the value of prothrombin time for predicting the severity and prognosis of septic patients

Abstract

To explore the predictive efficacy of prothrombin time (PT) with regarding for the severity and prognosis of septic patients, along with comparing with other routine coagulation parameters. A retrospective analysis was conducted. The clinical data of 302 septic patients who were admitted to the intensive care unit (ICU) of Tongji Hospital, Tongji Medical College of Huazhong University of Science and Technology from January 1 to December 31 in 2019 were enrolled. Demographic and basic clinical data were collected. Laboratory data, including PT, activated partial thromboplastin time (APTT), thrombin time (TT), fibrinogen (FIB), D-dimer, fibrin (fibrinogen) degradation product (FDP), antithrombin (AT), platelet count (PLT) at ICU admission were recorded, and sequential organ failure assessment (SOFA) score, acute physiology and chronic health evaluation II (APACHE II) score within 24 hours of admission to ICU were also collected. What's more, some major clinical events, such as septic shock, disseminated intravascular coagulation (DIC), etc. during ICU stay were also monitored. A follow-up 28 days observation of prognosis was performed. The patients were divided into the septic shock group and the non-septic shock group according to the occurrence of septic shock, and they were divided into the survival group and the non-survival group according to the 28-day prognosis. The differences in terms of above parameters between each two groups were compared. Spearman correlation method was used to analyze the correlation between routine coagulation parameters and SOFA score or APACHE II score. Receiver operator characteristic curve (ROC curve) was plotted to determine the predictive efficacy of each routine coagulation parameter with regarding to predict septic shock and 28-day mortality. Based on the cut-off value of PT, the septic patients were divided into two risk stratifications, and then the major clinical and end point outcome were compared. Kaplan-Meier survival curve analysis was applied to investigate the difference of the 28-day cumulated survival rate based on the different risk stratifications of PT level. Finally, multivariate Logistic regression analysis was used to explore whether prolonged PT level was an independent risk factor for septic shock and 28-day mortality. The 302 patients were all enrolled, including 120 patients with septic shock and 182 patients without. Seventy-five patients died within 28 days, while 227 survived. Comparing with the non-septic shock group or the survival group, the septic shock group or the non-survival group patients both had longer PT, APTT and TT, higher D-dimer, FDP and lower PLT, FIB and AT. Correlation analysis revealed that PT and PLT were better correlated with SOFA score (r values were 0.503 and -0.524, both P < 0.01), and PT was better correlated with APACHE II score (r = 0.407, P < 0.01). ROC curve analysis showed that PT had the most powerful predictive efficacy for septic shock and 28-day mortality. The area under the ROC curve (AUC) and 95% confidence interval (95%CI) were 0.831 (0.783-0.879) and 0.739 (0.674-0.805), respectively. The cut-off value were 16.8 s and 16.3 s, respectively, with the sensitivity of 64.2%, 72.0% and the specificity of 89.0%, 70.9%, respectively. Risk stratification based on PT level revealed that the patients with PT > 16.5 s (n = 103) had higher rate of 28-day mortality, incidence of septic shock and DIC, and score of SOFA and APACHE II comparing to those with PT ≤ 16.5 s (n = 199). Kaplan-Meier survival curve analysis showed that the 28-day cumulative survival rate was significantly lower in the patients with PT > 16.5 s than those with PT ≤ 16.5 s (52.43% vs. 86.93%; Log-Rank test: χ2 = 49.428, P < 0.001). Multivariate Logistic regression analysis revealed that PT > 16.5 s was an independent risk factor both for septic shock and 28-day mortality [model 1 (enrolled SOFA score): odds ratio (OR) and 95%CI were 6.003 (3.040-11.855), 4.842 (2.114-11.089); model 2 (enrolled APACHE II score): OR and 95%CI were 7.675 (4.007-14.702), 5.160 (2.258-11.793)]. Compared with other routine coagulation parameters, PT has the potential best predictive value for evaluating the severity of sepsis and the prognosis. When a patient is diagnosed with sepsis and has a result of PT longer than 16.5 s at ICU admission, the patient may have a higher risk of progression to septic shock and short-term death.