Diagnostic and prognostic role of platelets in patients with sepsis and septic shock

Studies investigating the prognostic role of platelets commonly include critically ill patients, whereas data regarding the prognostic impact of platelet count in patients admitted with sepsis and septic shock is limited. Therefore, the study investigates the prognostic role of platelet count in patients with sepsis and septic shock. Consecutive patients with sepsis and septic shock from 2019 to 2021 were included monocentrically. Blood samples were retrieved from the day of disease onset (day 1), days 2, 3, 5, 7 and 10. Firstly, the diagnostic value of platelet count was tested for septic shock compared to sepsis. Secondly, the prognostic value of platelet count was tested for 30-day all-cause mortality. Statistical analyses included univariable t-test, Spearman's correlation, C-statistics, Kaplan-Meier analyses, as well as multivariable mixed analysis of variance (ANOVA), Cox proportional regression analyses and propensity score matching. A total of 358 patients with sepsis and septic shock were included with a median platelet count of 176 x 10(6)/ml. The presence of thrombocytopenia (i.e. <150 x 10(6)/ml) was associated with increased risk of 30-day mortality (HR = 1.409; 95% CI 1.057-1.878; p = .019), which was still demonstrated after propensity score matching. During the course of sepsis, a nadir was observed on sepsis day 5 with a decrease in the mean platelet count by 21.5%. Especially serum lactate, mean arterial pressure and the presence of malignancies were found to predict platelet decline during the course of sepsis/septic shock. The presence of platelet decline >25% was associated with an increased risk of 30-day all-cause mortality (HR = 1.484; 95% CI 1.045-2.109; p = .028). Following platelet decline, recovery was observed from day 5 to day 10 (mean increase 7.5%). However, platelet recovery was not found to be associated with 30-day all-cause mortality (HR = 1.072; 95% CI 0.567-2.026; p = .832). In conclusion, both thrombocytopenia and platelet decline during the course of sepsis were associated with an increased risk of 30-day all-mortality in patients admitted with sepsis or septic shock. Plain Language Summary What is the context? center dot Despite improved treatment strategies in intensive care medicine, sepsis and septic shock represent one of the major causes of death at intensive care units worldwide. center dot Although it is known that platelets are associated with prognosis, most studies included "critically illness" patients and were not restricted to patients admitted with sepsis or septic shock. Furthermore, studies focusing on patients with sepsis were predominantly published prior to the sepsis-3 criteria. Specifically, the course of the platelet count during ICU hospitalization needs further investigation. What is new? center dot The present study suggests that the platelet count reflects a reliable tool for the diagnosis of septic shock during the first week of ICU hospitalization. center dot Furthermore, platelet count and the platelet-to-white-blood-cell-ratio are predictive for 30-day all-cause mortality in the presence of sepsis or septic shock. center dot Especially, a decrease in platelet count during the first 5 days of ICU hospitalizations was associated with an increased risk of 30-day all-cause mortality in patients with sepsis and septic shock, whereas the platelet recovery was not found to be associated with a worse prognosis. What is the impact? center dot This study provides further evidence that the platelet count represents a reliable tool for the diagnosis of septic shock and furthermore predicts short-term prognosis in patients admitted with sepsis or septic shock during the first 10 days of ICU hospitalization.