Sepsis is a heterogeneous disease and identifying sepsis subphenotypes can help optimize sepsis management.

To identify sepsis subphenotypes and risk stratification using procalcitonin trajectories.

Retrospective analysis of 800 cases admitted to the General Hospital of Ningxia Medical University and 202 adult patients with sepsis (age >18 years) in Gansu Provincial Hospital from January 1, 2021 to August 1, 2023 was performed. 597 patients from the General Hospital of Ningxia Medical University were randomized into the development cohort (60%) , and another 202 and 203 from Gansu Provincial Hospital, totaling 405 patients, were included in the validation cohort (40%) . Firstly, the development cohort was divided into survival and death groups to analyze the prognostic value of procalcitonin measurements for sepsis at different times, and ROC curves were plotted to assess predictive efficacy. Then, Group-based trajectory modeling (GBTM) based on repeated measurements of procalcitonin was performed to identify sepsis subphenotypes, which were characterized based on trends in procalcitonin changes and clinical features, and survival analysis and risk stratification were performed, and, Finally, the predictive model was validated.

In the development cohort, 512 patients survived and 85 died, and the overall 28-day mortality was 14.2%. In the validation cohort, 341 patients survived and 64 died, with an overall 28-day mortality of 16.3%. The death group had significantly higher PCT d3, PCT d5, and PCT d7 than the survival group (P<0.01) , and PCT d7 had the highest predictive efficacy with an area under the ROC curve of 0.833. The "Middle Start Rapid Rise" was characterized by respiratory dysfunction; the "Low Start Slow Decline" had the lowest comorbidity and critical care scores and was considered to be the baseline group; the "High Start Rapid Decline" was characterized by higher comorbidity and critical care scores; and the "High Start Slow Decline" was characterized by multiple organ dysfunction and had the highest value of critical care scores and was considered to be the most severe group on admission. Survival analyses of the four subphenotypes showed that "Middle Start Rapid Rise" had the highest mortality rate and was defined as the high-risk group, followed by "High Start Slow Decline" and was defined as the intermediate-risk group, "Low Start Slow Decline" and "High Start Rapid Decline" had the lowest mortality rate and were defined as the low-risk group. The relative distributions of calcitonin trajectories and comorbidities in the validation and development cohorts were generally consistent.

Procalcitonin trajectories can be used to identify sepsis subphenotypes, and the combination of procalcitonin values and trajectories can be used to achieve risk stratification for sepsis, providing a theoretical basis for clinicians to assess the prognosis of patients using procalcitonin trajectories.