Shapiro Decision Rule, Systemic Inflammatory Response Index, and Systemic Immune-Inflammation Index as Rapid...

Bacteremia is a serious condition that can progress to sepsis, septic shock, and multiple organ dysfunction syndrome (MODS) if not promptly treated. Blood culture is the gold standard for diagnosis but has a long turnaround time, low positivity, and risk of false positives, often leading to excessive culture sampling in the emergency department (ED). The Shapiro Decision Rule (SDR), Systemic Inflammatory Response Index (SIRI), and Systemic Immune-Inflammation Index (SII) offer rapid, low-cost alternatives. This study compared their accuracy for predicting bacteremia in ED patients undergoing blood culture.

This retrospective, single-center cross-sectional study included adult ED patients at Dr. Hasan Sadikin General Hospital, Bandung (May 2023-July 2025) who underwent blood culture and complete hematology testing. Patients with prior antibiotics (within 48 h), immunosuppression, active hematological disorders, or contaminated cultures were excluded. Sensitivity, specificity, predictive values, Youden index, ROC-AUC, the DeLong test, and multivariable logistic regression were computed in SPSS v25.

Of 745 patients meeting inclusion, 216 (29%) had positive cultures; the full eligible cohort was then analyzed, comprising 481 patients (111 with confirmed bacteremia, 370 without; prevalence 23.1%). SDR showed the highest discrimination (sensitivity 87.4%, specificity 51.9%; AUC 0.696, 95% CI 0.653-0.737; p<0.001), outperforming SIRI (79.3%, 41.4%; AUC 0.601, 95% CI 0.556-0.645; p<0.001) and SII (76.6%, 28.9%; AUC 0.508, 95% CI 0.462-0.554; p=0.799). The DeLong test confirmed SDR's AUC significantly exceeded those of SIRI and SII, and SDR remained an independent predictor of bacteremia after adjustment for heart failure and chronic kidney disease (p<0.001).

The Shapiro Decision Rule is significantly superior to the simple hematological indices SIRI and SII for predicting bacteremia with an AUC indicating moderate discrimination. It retains value as a practical exclusion tool to help rationalize blood-culture requests in the ED. Given the retrospective, single-center design, external validation is warranted before routine adoption.