Value of bronchial reversibility to salbutamol, exhaled nitric oxide and responsiveness to methacholine to corroborate the diagnosis of asthma in children

It's high time for the scholarly societies to standardize the bronchodilator responsiveness in children

“…Dear editor, I read with curiosity the remarkable article of Mallol et al 1 aiming at determining the performance of commonly used tests for asthma diagnosis -that is, spirometry, bronchodilator responsiveness (BDR) to salbutamol, methacholine challenge test, and fractional exhaled nitric oxide (F e NO) to validate the diagnosis of asthma in children. I acknowledge the authors for their captivating idea, and I agree with their conclusion that "spirometry, BDR, and F e NO have a poor performance to corroborate asthma diagnosis in children."…”

“…I acknowledge the authors for their captivating idea, and I agree with their conclusion that "spirometry, BDR, and F e NO have a poor performance to corroborate asthma diagnosis in children." However, in the methodology section of the aforementioned article, 1 three points related to the bronchodilator test caught my intention.…”

“…(i) Mallol et al 1 have defined the positive BDR as ≥12% increase from baseline in forced expiratory volume in 1 s (ΔFEV 1%B ), and they have argued their choice by citing as a reference the 2005 task force published by the American thoracic and the European respiratory societies (ATS/ERS). 2 The approach of Mallol et al 1 is practical but "debatable." In fact, according to the ATS/ERS, 2 a positive BDR (regardless of the age) is a ΔFEV 1%B ≥ 12% and a ΔFEV 1AC (absolute change) ≥200 mL and/or an increase from baseline in forced vital capacity (ΔFVC %B ) ≥12%, and a ΔFVC AC ≥200 mL.…”

“…In fact, according to the ATS/ERS, 2 a positive BDR (regardless of the age) is a ΔFEV 1%B ≥ 12% and a ΔFEV 1AC (absolute change) ≥200 mL and/or an increase from baseline in forced vital capacity (ΔFVC %B ) ≥12%, and a ΔFVC AC ≥200 mL. Consequently, Mallol et al 1 "omitted" to express the FEV 1 BDR as an increase in Δ AC , and to evaluate an important spirometric datum (i.e., FVC). Notwithstanding its huge use in real-life clinical situation, Δ %B presents two key limitations.…”

“…3 On the other hand, patients with the highest basal FEV 1 displayed the smallest ΔFEV 1%B . 3 The approach of Mallol et al 1 to "omit" ΔFEV 1AC is realistic, since ΔFEV 1AC exhibits some correlations to age and height, and its changes are greater in tall children than in short ones. 3 In children, some scholarly societies 2,4 still indorse one spirometric standardized and reproducible datum (i.e., FVC) for at least two reasons.…”