Procalcitonin as a biomarker of bacterial infection in critically ill patients admitted with suspected Sepsis in Intensive Care Unit of a tertiary care hospital

OBJECTIVE: To compare the diagnostic accuracy of procalcitonin (PCT), C- reactive protein (CRP), total leukocyte count (TLC) and lactate in critically ill patients admitted with suspicion of sepsis. METHODS: It was a cross sectional study conducted at the department of Chemical Pathology and Endocrinology AFIP, Rawalpindi, in collaboration with Medical and surgical intensive care units (ICU) of CMH Rawalpindi from January 2019 to December 2019. A total of 126 patients of both genders with age above 18 years and fulfilling the inclusion criteria of systemic inflammatory response syndrome (SIRS) were inducted in the study. RESULTS: Out of 126 patients 82 (65%) patients have positive blood culture results. Male predominance was noted in patients with positive blood culture. Out of 82 patients with positive blood culture results 69(84%) patients have positive PCT results as well whereas 13(15%) patients with positive blood culture results have negative PCT values. 57(69%) patients had Gram negative bacterial infection and 25(30%) patients had Gram positive bacterial infection. Significant difference was noted between the medians of PCT in blood culture positive and blood culture negative group (p value< 0.05) whereas no significant difference was found between medians of CRP, TLC and lactate between blood culture positive and blood culture negative patients (p value > 0.05). ROC curve analysis of PCT, CRP and TLC were done, keeping blood culture as reference standard, PCT showed largest area under the curve (AUC) and clearly outperformed TLC and CRP. PCT showed AUC of 0.781 as compared to CRP and TLC, which was 0.568 and 0.617 respectively. PCT showed sensitivity of 93.9%, specificity of 47.7%, positive predictive value (PPV) of 77% and negative predictive value (NPV) of 80.8%. CONCLUSION: Higher NPV makes it a reliable marker for screening out sepsis in suspected cases.