Evaluation of clinically and physiologically atypical asthma: If it doesn't wheeze it may still be asthma

ABSTRACT

Objective: Children with asthma-like symptoms may not clinically wheeze. The objectives of this study were to evaluate if children, without physician-documented wheeze, wheeze during bronchial-challenge-testing (BCT), and if measurements of O₂Sat and respiratory rate during BCT improve the BCT sensitivity? Methods: Seven hundred and twenty-four children, who were referred for suspicion of asthma, performed a BCT. Positive BCT was determined by the provocation concentration (PC) which resulted in a 20% decrease in FEV₁ (PC₂₀), (in those who were able to perform spirometry, group B), or (in those unable to perform spirometry, group A) a 50% increase in respiratory rate (PC_RR), or a 5% decrease in oxygen-saturation (PC_O2-Sat) or appearance of wheezing (PC_wheeze). Results: Five hundred and seven BCTs were positive: group A n = 89 age, median (IQR), 3 (2.5–3.7) years (17.6%), were unable to perform spirometry, and group B n = 418 age 10.7 (6.8–15.6) years (82.4%), were able to perform spirometry. Children, without physician-documented wheeze in the total population (groups A plus B), were more likely (65.5%) to have a positive BCT without wheeze compared with those with physician-documented wheeze (41.0%, P < 0.001). In group A, adding PC_RR and PC_O2-Sat increased BCT sensitivity by 23.6%. Conclusions: Many children in both groups did not wheeze despite reaching BCT endpoints. Children without physician-documented wheeze tended not to wheeze at BCT. This may result in clinical under-diagnosis of asthma if depending on the presence of wheeze. In young children, adding PC_RR and PC_O2-Sat substantially increases BCT sensitivity and may improve asthma diagnosis.

KEYWORDS:

• Asthma diagnosis
• bronchial challenge test
• children
• wheeze

Acknowledgements

We thank Professor Mona Boaz, PhD, Epidemiology and Research Unit, Wolfson Medical Center, who advised on statistics.

Declaration of interest

Dr Ater, Dr Amirav, Dr Attias, Dr Nakash, Dr Newhouse, and Dr Mandelberg declare that they have no competing interests and did not receive any financial support.

Contribution

Dr Ater, Dr Mandelberg, Dr Attias and Dr Nakash recruited patients for the study. Dr Ater and Dr Mandelberg wrote the first draft of the manuscript. Dr Amirav and Dr Newhouse significantly revised and edited the manuscript.

Dr Mandelberg is the guarantor of the paper, takes responsibility for the integrity of the work as a whole, from inception to published article.