Prognostic value of dynamic procalcitonin (PCT-Δ) for adverse outcomes in patients with pyogenic liver abscess: a retrospective cohort study

To characterize the clinical profile of pyogenic liver abscess (PLA) complicated by sepsis and investigate the prognostic value of dynamic Procalcitonin (PCT-Δ, peak-to-trough difference) for adverse outcomes (primary: death, multiple organ dysfunction syndrome MODS; secondary: hospital stay > 14 days) in PLA patients, and to analyze its non-linear association with adverse outcomes. This retrospective cohort study enrolled 170 consecutive PLA patients at a tertiary hospital in Guangzhou (January 2020–December 2024). Sepsis was defined per Sepsis-3 criteria (infection + acute organ dysfunction, SOFA score increment ≥ 2 or absolute score > 2) and was assessed throughout hospitalization. Clinical/laboratory data, including PCT levels at admission, peak, and trough during hospitalization, were collected. Restricted cubic spline (RCS) analysis with 3 knots explored non-linear associations between PCT-Δ and adverse outcomes. Receiver operating characteristic (ROC) curves with 1000-iteration bootstrap resampling and calibration curves evaluated the prognostic performance of PCT-Δ, with multivariable logistic regression models adjusted for sex, age, diabetes, biliary disease, malignancy, and abscess size. Of 170 patients, 72 (42.35%) developed sepsis during hospitalization. The cohort had a median age of 61 years (IQR 51.0–70.0) with male predominance (67.60%). PCT-Δ (median 30.03 vs. 1.28 ng/mL, P < 0.001) was significantly higher in PLA patients with adverse outcomes. RCS analysis revealed a significant non-linear relationship between PCT-Δ and adverse outcomes (P-overall < 0.001, P-nonlinear = 0.002): the risk of adverse outcomes rose rapidly when PCT-Δ was 0–50 ng/mL and slowed above 50 ng/mL. ROC analysis showed robust prognostic performance: Model 1 (PCT-Δ alone) AUC = 0.833 (95% CI: 0.771–0.895); Model 2 (adjusted for covariates) AUC = 0.843 (95% CI: 0.784–0.902). Bootstrap validation yielded a corrected C-statistic of 0.834 (AUC SD = 0.0423), with calibration curves showing excellent agreement between predicted and observed probabilities. Sepsis complicating PLA is associated with poor outcomes. PCT-Δ is significantly non-linearly associated with adverse outcomes in PLA patients and has good prognostic value for this population. This dynamic biomarker may assist clinicians in risk stratification of PLA patients, particularly those with complicated sepsis. However, the application of PCT-Δ is limited by its time window of measurement, and prospective multicenter validation is needed to confirm its clinical utility. Not applicable.