Introduction: Ongoing respiratory symptoms throughout childhood is often diagnosed as asthma in preterm children. Whether prematurity-associated lung disease (PALD) is actually asthma is subject to intense debate. The recent ERS clinical practice guidelines for the diagnosis of asthma in children aged 5?16 years (Gaillard et al. ERJ 2022) advocates for the use of two positive, evidence-based tests to confirm the diagnosis of asthma. We used the 2022 ERS guidelines to determine the rates of asthma in children born very-preterm (?32 weeks gestation).

Methods: Preterm children (N=128; mean±SD age=10.4±2.2) completed an ISAAC respiratory questionnaire, underwent spirometry, bronchodilator response (BDR) and fractional exhaled nitric oxide (FeNO) testing. A diagnosis of asthma was defined by two positive tests of either: a positive BDR (?12% ? in FEV₁) and/or abnormal spirometry (FEV₁ z-score<-1.645) and/or high FeNO (?25ppb).

Results: Respiratory symptoms were reported by 45% of the cohort in the past 3 months, with 25% of the cohort having previously received a clinical diagnosis of asthma. 51 individuals (39.8%) had at least one positive diagnostic for asthma (BDR, abnormal spirometry or high FeNO), however only 14% of the cohort met the new diagnostic criteria for asthma. Of those in the cohort with a previous clinical diagnosis of asthma (n=32), 12.5% (n=4) met the new asthma diagnostic criteria. Of the 18 individuals who met the new diagnostic criteria, only 3 reported any respiratory symptoms.

Conclusion: Prematurity-associated lung disease is frequently mis-diagnosed as asthma in those born very-preterm. However, there is likely a subset that do fit the asthma phenotype and may benefit from asthma treatment.