Comparative analysis of procalcitonin kinetics between the first and second infectious events in the intensive care...

Sepsis arises from a dysregulated host response to infection. After the initial hyperinflammatory phase, some patients may develop sepsis-induced immunosuppression, predisposing them to new infectious episodes whose immunological behavior remains poorly understood. Procalcitonin (PCT) is a widely used biomarker in sepsis management, but its kinetics during recurrent infections have not been systematically evaluated.

Retrospective cohort study at a tertiary university hospital in Argentina, including adult intensive care unit patients who experienced two infectious events separated by 7 to 30 days. PCT levels and SOFA scores were analyzed using mixed-effects models, adjusting for infection source, bacterial isolation, and renal function.

55 patients met inclusion criteria. During the first infectious event, PCT levels were significantly higher: 42.13 pg/mL (95% CI 33.59-50.67) and showed a rapid daily decline of 5 pg/mL (95% CI -5.9 to -4; p<0.01). In contrast, the second event showed lower PCT peaks: 32.47 pg/mL (-9.66 pg/mL difference; p<0.01) and a slower decline (interaction coefficient 1.45; p=0.04). Organ dysfunction was greater during the first event, with higher delta SOFA scores compared to the second median 5 vs. 2 (coefficient -2.53; p<0.01).

These findings show distinct PCT kinetics between initial and subsequent infectious episodes, suggesting attenuated inflammatory responses and reduced organ dysfunction during the second event. The observed alteration in PCT values could reflect a change in the dynamics of the immune response secondary to the first infectious event.