Diagnostic Accuracy of Various Biomarkers of Sepsis (Serum Pro-Calcitonin, High-Sensitivity C-reactive Protein, and C-reactive Protein) and Band Cell Percentage in Critically lll Patients: A Prospective, Observational, Cohort Study.

Background: Despite the advances in medical sciences, the morbidity and mortality due to sepsis in critically ill medical or surgical patients remains high, hence the need for an early and accurate diagnosis. In the current armamentarium, we have various biomarkers such as procalcitonin (PCT), high-sensitivity C-reactive protein (hs-CRP), CRP, and band cell percentage for an early clue.

Aims: This study explores the accuracy of these markers in distinguishing sepsis from systemic inflammatory response syndrome (SIRS) and their correlation with sequential organ failure assessment (SOFA) scoring in critically ill patients.

Materials And Methods: After ethical committee approval and written informed consent from guardians, 180 consecutive patients, with clinically suspected infection from any source fulfilling at least two criteria of SIRS, were enrolled and 150 eligible patients were investigated and analyzed prospectively in one cohort, which was later subdivided into two different groups (Group A and Group B) based on microbiology reports, as having SIRS or sepsis, respectively. Samples for cultures (blood, tracheal, or urine as required), biomarkers such as PCT, hs-CRP, and CRP, and band cell percentage were sent from each patient on days 1, 2, 3, and 5 and whenever there were fever spikes. Clinical follow-up was done for 28 days, and demographics, ventilator days, duration of intensive care unit (ICU) stay, and the survival rates were noted.

Statistical Analysis: Receiver operating characteristics, area under curve (AUC-ROC) was used for each of the biomarker variables to decide the cutoff values and performance. Correlation coefficient was also seen for each of the biomarkers with SOFA scoring.

Results: Attributes of performance for all the biomarkers were satisfactory but was best for PCT (AUC-ROC of 0.987) followed by band cell percentage (0.881). SOFA scoring could also be used with good diagnostic accuracy (AUC-ROC of 0.920). SOFA score correlated best with PCT among the four biomarkers in diagnosing sepsis (Spearman's coefficient of + 0.734). Band cell percentage was significantly higher in the expired group of sepsis patients than survived patients ( = 0.02) and correlated well with ICU stay and 28-day mortality than rest (Spearman's coefficient of - 0.54).

Conclusions: The addition of PCT to the standard workup of critically ill patients with suspected sepsis increases diagnostic certainty and generates improved patient management. Band cell percentage also provides a cost-effective alternative to PCT with an analogous diagnostic performance.