Related Experiment Video
Updated: Sep 8, 2025
A Neonatal Imaging Model of Gram-Negative Bacterial Sepsis
Published on: August 12, 2020
Utility of the systemic immune-inflammation index to predict serious bacterial infections in infants with fever
Ali Güngör1, Aytaç Göktuğ1, Raziye Merve Yaradılmış1
1Department of Pediatric Emergency Medicine, Dr. Sami Ulus Maternity and Child Health and Diseases Training and Research Hospital, Ankara, Turkey.
Insights
The systemic immune-inflammation index (SII) can help predict serious bacterial infections (SBIs) in infants with fever without source (FWS). High SII values are predictive of urinary tract infections in infants, offering a cost-effective diagnostic tool.
Area of Science:
- Pediatric Emergency Medicine
- Infectious Diseases
- Clinical Diagnostics
Background:
- Fever without source (FWS) is common in infants, necessitating accurate methods to identify serious bacterial infections (SBIs).
- Existing inflammatory markers have limitations in predicting SBIs in this population.
- The systemic immune-inflammation index (SII) is a novel marker derived from routine blood counts.
Purpose of the Study:
- To evaluate the utility of the systemic immune-inflammation index (SII) in predicting SBIs in infants presenting with FWS.
- To compare the efficacy of SII against other inflammatory markers like C-reactive protein (CRP), absolute neutrophil count (ANC), and white blood cell (WBC) count in diagnosing SBIs.
Main Methods:
- A retrospective study of 223 infants (1-4 months) with FWS evaluated in a pediatric emergency department.
- Infants were categorized into two groups: those with SBI and those without SBI.
- Analysis included comparison of inflammatory markers (SII, CRP, ANC, WBC) and their predictive values for SBI, with a focus on urinary tract infections (UTIs).
Main Results:
- SBIs were predominantly UTIs (62/223 infants), associated with higher hospitalization rates and longer stays.
- The mean SII was significantly higher in the SBI group (795.76) compared to the non-SBI group (318.24) (p < 0.001).
- SII demonstrated strong diagnostic performance (AUC: 0.84), comparable to CRP (AUC: 0.89) and ANC (AUC: 0.86), for predicting SBIs.
Conclusions:
- Elevated CRP and SII values are significant predictors of UTIs without bacteremia in infants with FWS.
- The SII is a valuable, cost-effective tool for predicting SBIs in infants, calculable from routine hemogram results without additional blood draws.
Introduction:
This study analyzed the utility of the systemic immune-inflammation index (SII) in predicting serious bacterial infections (SBIs) in infants with fever without a source (FWS).
Methods:
Infants (aged 1-4 months) evaluated in the pediatric emergency department for FWS were divided into two groups: with SBI and without SBI. The efficacy of inflammatory markers in predicting SBI was compared.
Results:
The study included 223 infants with a mean age of 76.65 ± 25.42 days; 62 (27.8%) of them were included in the SBI group, and all of them were diagnosed with a urinary tract infection (UTI). The hospitalization rate and length of hospital stay were significantly higher in UTI patients (p < 0.001 for each). The mean SII was 795.76 ± 475.85 in the SBI group and 318.24 ± 300.70 in the non-SBI group, and there was a significant difference between the groups (p < 0.001). In diagnosis of SBI, the area under the curve values were found to be 0.89 [95% confidence interval (CI): 0.85-0.94] for C-reactive protein (CRP), 0.86 (95% CI: 0.81-0.91) for absolute neutrophil count (ANC), 0.84 (95% CI: 0.78-0.89) for the SII, and 0.81 (95% CI: 0.74-0.87) for WBC. In the multivariate logistic regression analysis, high CRP and SII values were found to be predictive factors for UTI without bacteremia (p < 0.001 and p = 0.008, respectively).
Conclusion:
We found that high CRP and SII values could be predictive for UTI without bacteremia in infants with FWS. The SII may be preferred because it can be easily calculated using the hemogram results, is not accompanied by extra costs, and does not require further blood collection.
