Diagnostic Accuracy of Serum Procalcitonin (PCT) as an Early Biomarker of Neonatal Sepsis using Blood Culture as Gold Standard

Objective: To ascertain the diagnostic accuracy of serum PCT as an early biomarker of neonatal sepsis using blood culture as gold standard, so that the condition could be diagnosed and managed early to prevent and reduce morbidity and mortality in neonates. Study Design: Cross-sectional study. Place and Duration of Study: Dr. Ziauddin University Hospital, Karachi, from March 2019 to December 2019. Methodology: A total of 171 neonates, 1-29 days of age, presented with clinical diagnosis of neonatal sepsis, were included in this study. Patients' data regarding age, gender, birth weight, prematurity and premature rupture of membranes (PROM) were collected. Blood cultures were performed in Microbiology Department; and Serum PCT was analyzed on Electrochemiluminescence Immunnoassay Analyzer (Cobas e601). Diagnostic accuracy, including sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of PCT were calculated with contingency tables using blood culture findings as gold standard. Results: Out of 171 clinically diagnosed cases of neonatal sepsis, 86 (50.3%) were confirmed as having neonatal sepsis (blood culture positive). There was a significant difference in serum PCT levels in both the groups. The sensitivity of PCT was 97.7%; specificity 70.6%; PPV 77.1; NPV 96.8%; likelihood ratio of a positive test (LR+ve) 3.32; likelihood ratio of a negative test (LR - ve) 0.03, and cumulative diagnostic accuracy of PCT 84.2%. Conclusion: PCT is a very useful biomarker for the early diagnosis of neonatal sepsis, showing 84.2% diagnostic accuracy. Thus PCT can help in making early clinical decisions regarding management of patients.