Predictive value of dynamic plasma biomarkers for clinical outcomes in pediatric sepsis

Pediatric sepsis is a heterogeneous syndrome; data on early biomarker kinetics and their link to severity are scarce.

We prospectively enrolled 80 children with sepsis (March 2022 - June 2024). C-reactive protein (CRP), procalcitonin (PCT), erythrocyte sedimentation rate (ESR), interleukin-6 (IL-6), serum amyloid-A (SAA), and D-dimer were measured at admission (T0), 72 hours (T1) later and on Day 7 (T2). Disease severity was assessed using the pediatric Sequential Organ Failure Assessment (pSOFA); length of stay (LOS) was recorded. Baseline values, Day 7 levels, and changes Δ(T2-T0) were correlated with pSOFA and LOS.

Baseline inflammatory profiles differed by etiology: median CRP and PCT on admission were roughly doubled in bacterial versus viral disease, while IL‑6 was highest in respiratory and abdominal infections. Nevertheless, all six markers decreased significantly over seven days (p ≤ 0.015) and the proportional declines were uniform across pathogens or foci (interaction p > 0.18). Higher admission CRP, PCT, IL‑6 and D‑dimer modestly correlated with greater organ dysfunction (r ≤ 0.55), whereas steeper week‑long falls in the same markers tracked with larger pSOFA improvement (r = -0.41 to -0.53; all p ≤ 0.002). SAA showed a weaker inverse association (r = -0.32, p = 0.008), whereas the decline in ESR was not significant. A pragmatic two‑step algorithm (admission CRP  ≥ 60 mg/L, PCT  ≥ 3 ng/mL, IL‑6  ≥ 200 pg/mL or D‑dimer  ≥ 1.5 mg/L; plus a ≥ 50% drop in IL‑6 or PCT within 72 h) identified children who ultimately required intensive care unit (ICU) care or stayed ≥ 7 days with an area‑under‑the‑curve of 0.91.

Both initial elevations and early declines in CRP, PCT, IL-6 and D-dimer mirror organ dysfunction and hospitalization duration in pediatric sepsis. Serial monitoring of these readily available markers may improve early risk stratification and guide therapy.