Calculators & Tools

Asthma Predictive Index (API)

Predicts later school-age asthma in a preschool child with recurrent wheeze.

1 What is the Asthma Predictive Index (API)?

The Asthma Predictive Index (API) is a respiratory scoring tool used in paediatric practice. Predicts later school-age asthma in a preschool child with recurrent wheeze. It scores 6 criteria and interprets the total across 2 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 respiratory
  • 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 6 criteria: ≥3 episodes of wheezing per year during the first 3 years (required); MAJOR - parent with physician-diagnosed asthma; MAJOR - physician-diagnosed atopic dermatitis in the child; MINOR - peripheral blood eosinophilia ≥ 4 %; MINOR - wheezing apart from colds; MINOR - allergic rhinitis diagnosed in the child. Totals are then banded: any score - Negative: frequent-wheeze criterion plus ≥1 major OR ≥2 minor criteria are needed for a positive index; 6 criteria or more - Positive API: positive stringent API - substantially higher risk of asthma at school age (about 4-10× that of a negative index). Supports closer follow-up and a controller trial when symptoms warrant.
  • Positive (stringent) API = frequent wheezing PLUS ≥1 major OR ≥2 minor criteria.
  • A negative API has a strong negative predictive value (~95%) for school-age asthma.
  • Source: Castro-Rodríguez JA et al. A clinical index to define risk of asthma in young children with recurrent wheezing. Am J Respir Crit Care Med 2000;162:1403-6.

4 Frequently asked questions

How many criteria does the Asthma Predictive Index (API) use?

6. They are ≥3 episodes of wheezing per year during the first 3 years (required); MAJOR - parent with physician-diagnosed asthma; MAJOR - physician-diagnosed atopic dermatitis in the child; MINOR - peripheral blood eosinophilia ≥ 4 %; MINOR - wheezing apart from colds; MINOR - allergic rhinitis diagnosed in the child.

What do the bands of the Asthma Predictive Index (API) mean?

The total is interpreted as: any score - Negative: frequent-wheeze criterion plus ≥1 major OR ≥2 minor criteria are needed for a positive index; 6 criteria or more - Positive API: positive stringent API - substantially higher risk of asthma at school age (about 4-10× that of a negative index). Supports closer follow-up and a controller trial when symptoms warrant.

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?

Positive (stringent) API = frequent wheezing PLUS ≥1 major OR ≥2 minor criteria.

Does it work offline?

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

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.