Optimizing Management of Febrile Young Infants Without Serum Procalcitonin
Bibliographic record
Abstract
BACKGROUND: Febrile young infants are at risk of invasive bacterial infections (IBIs; bacteremia or bacterial meningitis). American Academy of Pediatrics (AAP) guidelines recommend that when procalcitonin testing is unavailable, C-reactive protein (CRP), absolute neutrophil count (ANC) and temperature should be used to identify low-risk infants. We sought to determine the optimal combination of these inflammatory markers to predict IBI when procalcitonin is unavailable. METHODS: This was a secondary analysis of prospectively collected data for all febrile infants aged 60 days or younger evaluated at a tertiary pediatric emergency department (January 2018 to July 2023). Previously healthy term infants aged 8 to 60 days with rectal temperatures of 38.0°C or greater meeting AAP inclusion/exclusion criteria were analyzed. A decision rule was derived by classification and regression tree analysis with 10-fold cross-validation then compared to AAP-recommended thresholds of ANC ≤ 5200/mm3, CRP ≤ 20 mg/L, and temperature ≤ 38.5°C. RESULTS: Among 1987 infants, 38 (1.9%) had IBIs. The AAP-recommended thresholds missed no IBIs (sensitivity: 100.0% [95% CI, 88.6%-100.0%]; negative predictive value (NPV): 100.0% [95% CI, 99.5%-100.0%]; specificity: 50.7% [95% CI, 48.5%-53.0%]). Optimal derived thresholds were CRP ≤ 22.2mg/L, temperature ≤ 39.0°C, and ANC ≤ 4500/mm3; urinalysis and age were not selected. The derived rule also missed no IBIs (sensitivity: 100.0% [95% CI, 88.6%-100.0%]; NPV: 100.0% [95% CI, 99.7%-100.0%]); however, specificity improved to 83.8% (95% CI, 82.1%-85.4%). Area under the receiver operating curve for the cross-validated rule (91.9% [95% CI, 91.1%-92.7%]) was higher than at AAP-recommended thresholds (75.4% (95% CI, 74.3%-76.5%]). CONCLUSIONS: The combination of ANC, CRP, and temperature at statistically derived thresholds improved diagnostic accuracy for identifying infants at low risk of IBIs compared to AAP-recommended thresholds.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".