The ‘clinically significant’ bronchodilator responsiveness (BDR) in children: a comparative study between six definitions of scholarly societies and a mini-review

Objective: To compare the percentages of children with and without airway obstruction (obstructive and non-obstructive groups, respectively) presenting a ‘clinically significant’ BDR according to the following definitions: GINA: FEV1 increase >12% predicted (∆Predicted), ATS/ERS: FEV1 increase ≥12% initial (∆Initial) and ∆FEV1 absolute (∆) ≥200 ml and/or ∆FVCInitial ≥12% and ∆FVC ≥200 ml, British thoracic society (BTS): ∆FEV1Initial ≥12%, National asthma education and prevention program (NAEPP): ∆FEV1Initial ≥12% and ∆FEV1 > 200 ml, Group of research on advances in pediatric pneumology: ∆FEV1Initial ≥12% or ∆PEFInitial ≥20%, and South African thoracic society (SATS): ∆FEV1Initial ≥12% or ∆FEV1 >200 ml and/or ∆FVCInitial ≥12% or ∆FVC >200 ml. Methods: This was a multicenter comparative study involving 278 children aged 6 to16 years: obstructive group (FEV1/FVC < lower-limit-of-normal, n = 116) and non-obstructive group (FEV1/FVC ≥ lower-limit-of-normal, n = 162). Spirometry was performed before/after a bronchodilator test. The Cochrane Q test was used to compare the percentage of responders according to the six definitions. Results: The percentages of responders among the obstructive [ranging from 51.72 (NAEPP) to 74.14% (SATS)] and the non-obstructive [ranging from 0.62 (NAEPP, BTS) to 8.64% (SATS)] groups were definition-dependent. Conclusion: In children, a ‘clinically significant’ BDR is definition-dependent.