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Step-by-Step (Febrile Infant ≤90 days)

Sequential European approach to the well-appearing febrile young infant. Work down in order - the first positive step decides risk.

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1 What is the Step-by-Step (Febrile Infant ≤90 days)?

The Step-by-Step (Febrile Infant ≤90 days) is a infectious scoring tool used in paediatric practice. Sequential European approach to the well-appearing febrile young infant. Work down in order - the first positive step decides risk. It scores 5 criteria and interprets the total across 5 bands, so the number always arrives with the severity it implies rather than on its own. In PediAid each criterion is shown as a labelled option with the weight it carries, so the total can be checked rather than taken on trust.

2 When to use it

  • Grading severity at the bedside in infectious
  • Recording an objective severity band in the case notes
  • Deciding when a total crosses the threshold for escalation
  • Re-scoring to track whether a child is improving or deteriorating
  • Checking the exact criteria of a score used infrequently

3 Formula & method

The score sums 5 criteria: Step 1 - Ill appearing; Step 2 - Age ≤ 21 days; Step 3 - Leukocyturia (positive urine dipstick/microscopy); Step 4 - Procalcitonin ≥ 0.5 ng/mL; Step 5 - CRP > 20 mg/L or ANC > 10 000 /µL. Totals are then banded: any score - Low risk: no flags - low risk of invasive bacterial infection (NPV ≈99.3%). Well infants >21 days with normal biomarkers may be managed without empirical antibiotics with close follow-up, per local policy; 1 risk flag or more - Intermediate risk: cRP >20 mg/L or ANC >10 000 only - intermediate risk. Observation ± admission; consider lumbar puncture and antibiotics per local protocol; 2 risk flags or more - High risk: leukocyturia or procalcitonin ≥0.5 - high risk. Full septic work-up including urine culture, blood culture ± LP, and empirical antibiotics; 4 risk flags or more - High risk - young age: age ≤21 days - treat as high risk regardless of biomarkers: full sepsis work-up including lumbar puncture, admit and start empirical antibiotics; 8 risk flags or more - High risk - ill appearing: ill-appearing infant - highest risk. Immediate full sepsis evaluation, empirical antibiotics and admission.
  • Steps are hierarchical: assess in order and stop at the first positive step.
  • Source: Gomez B et al. Validation of the "Step-by-Step" approach in the management of young febrile infants. Pediatrics 2016;138:e20154381.

4 Frequently asked questions

How many criteria does the Step-by-Step (Febrile Infant ≤90 days) use?

5. They are Step 1 - Ill appearing; Step 2 - Age ≤ 21 days; Step 3 - Leukocyturia (positive urine dipstick/microscopy); Step 4 - Procalcitonin ≥ 0.5 ng/mL; Step 5 - CRP > 20 mg/L or ANC > 10 000 /µL.

What do the bands of the Step-by-Step (Febrile Infant ≤90 days) mean?

The total is interpreted as: any score - Low risk: no flags - low risk of invasive bacterial infection (NPV ≈99.3%). Well infants >21 days with normal biomarkers may be managed without empirical antibiotics with close follow-up, per local policy; 1 risk flag or more - Intermediate risk: cRP >20 mg/L or ANC >10 000 only - intermediate risk. Observation ± admission; consider lumbar puncture and antibiotics per local protocol; 2 risk flags or more - High risk: leukocyturia or procalcitonin ≥0.5 - high risk. Full septic work-up including urine culture, blood culture ± LP, and empirical antibiotics; 4 risk flags or more - High risk - young age: age ≤21 days - treat as high risk regardless of biomarkers: full sepsis work-up including lumbar puncture, admit and start empirical antibiotics; 8 risk flags or more - High risk - ill appearing: ill-appearing infant - highest risk. Immediate full sepsis evaluation, empirical antibiotics and admission.

Does the score replace clinical judgement?

No. It is a structured way to record and communicate severity. A clinician concerned about a child should act on that concern regardless of the total.

Where does this score come from?

Steps are hierarchical: assess in order and stop at the first positive step.

Does it work offline?

Yes. Score definitions are bundled with the PediAid app, so the score computes without a connection.

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For qualified clinicians. This page and the PediAid app are a clinical aid only. Calculations and reference data must be verified against the patient's clinical context, the source guideline and your local protocols before any treatment decision is made.