Abstract
OBJECTIVE: Central line-associated bloodstream infections (CLABSIs) are life-threatening complications in critically ill patients, necessitating early identification for timely intervention. This study evaluates the predictive performance of Systemic Inflammatory Response Index (SIRI), a novel composite marker derived from routine blood counts, for early prediction of CLABSI within first two calendar days following central venous catheter (CVC) insertion. METHOD: In this observational study at a tertiary ICU, 234 adults with CVCs for over two days were classified as CLABSI-positive or negative per CDC/NHSN criteria. SIRI was calculated using the formula (neutrophils×monocytes/lymphocytes) based on day 2 complete blood counts. Logistic regression and receiver operating characteristic (ROC) curve analysis was done to determine diagnostic performance. RESULTS: CLABSI was diagnosed in 39 patients. Median SIRI values were significantly higher in CLABSI group (37.3 vs. 12.0; p<0.001). In univariate logistic regression, SIRI emerged as an independent predictor of CLABSI (OR=1.0097; 95% CI: 1.001-1.018; p=0.015). ROC analysis demonstrated a moderate discriminative power with AUROC=0.72 (95% CI: 0.64-0.80). At optimal threshold, SIRI achieved 84.6% sensitivity, 52.8% specificity, 58.1% accuracy, 26.4% positive predictive value (PPV) and a notably high negative predictive value (NPV) of 94.5%, supporting its value as an early rule-out marker for CLABSI. CONCLUSION: SIRI, derived from routine complete blood counts, shows strong potential as a non-invasive, early screening marker for CLABSI. Its high sensitivity and NPV support its use for early rule-out, especially in settings lacking rapid diagnostics. Further prospective validation is warranted.