Biomarkers in sepsis-looking for the Holy Grail or chasing a mirage!

Table 4 Procalcitonin for prognosis of sepsis

Ref.	Type of study	Patient population	Aim	No. of patients/studies	Results	Conclusion of study
Ryu et al[52], 2015	Observational	Adults	To compare changes in PCT and CRP concentration in critically ill septic patients to determine which marker better predicts outcome	157 patients; 171 episodes	CPCTc and CRPc are significantly associated with treatment failure (P = 0.027 and P = 0.03 respectively) and marginally significant with 28 d mortality (P = 0.064 and 0.062 respectively). AUC for prediction of treatment success-PCTc-0.71 (95%CI: 0.61-0.81); CRPc-0.71 (95%CI: 0.61-0.81); AUC for survival prediction-PCTc-0.77 (95%CI: 0.66-0.88); CRPc-0.77 (95%CI: 0.67-0.88)	Changes in PCT and CRP concentrations were associated with outcomes of critically ill septic patients. CRP may not be inferior to PCT in predicting outcomes in these patients
Patnaik et al[32], 2020	Meta-Analysis	Adults	To evaluate the results of all non-clearance of serial PCT as a mortality predictor	10 studies, 1974 patients	AUC varied between the studies between 0.52 and 0.86. Overall AUC-0.711 (95%CI: 0.662-0.760) under fixed effect model and 0.708 (95%CI: 0.648-0.769) under random effect model. Overall proportion of mortality-37.54%	PCT non clearance is a marker for increased mortality. Optimal cut off points for PCT non clearance in septic patients admitted to ICU are not known
Park et al[53], 2013	Observational	Adults	To evaluate the value of PCT in women with APN at ED	240	AUC for predicting 28 d mortality for PCT-0.68. For predicting mortality, a cut off value of 0.42 ng/mL, sensitivity was 80% and specificity was 50%. Disease classification systems were predicted to be superior to PCT in predicting 28 d mortality	By distinguishing the severity of sepsis related to APN mortality, PCT levels help clinicians in disease severity classification and treatment decisions at ED
Oberhoffer et al[54], 1999	Observational	Adults	To predict outcome with traditional and new inflammatory markers in septic patients	242	AUC for PCT was 0.878 which was highest as compared to other markers	PCT may be a better marker than other inflammatory markers, CRP, leukocyte count, body temperature to identify patients endangered by severe infection or sepsis
Arora et al[31], 2015	Meta-Analysis	Adults	To study the procalcitonin levels in survivors and non survivors of sepsis	25 studies; 2353 patients	Mean difference in procalcitonin levels between survivors and non survivors on day 1 (P = 0.02) and day 3 (P = 0.03) was statistically significant	Significantly lower levels of procalcitonin were observed in survivors as compared to non survivors in early stages of sepsis

APN: Acute pyelonephritis; AUC: Area under the receiver operator characteristic curve; CRP: C-reactive protein; CRPc: Clearance of CRP; PCT: Procalcitonin; PCTc: Clearance of PCT.