A forced expiratory flow at 25‐75% value <65% of predicted should be considered abnormal: A real-world, cross-sectional study

Forced expiratory volume in 1 second (FEV₁) is considered an important parameter for asthma diagnosis and follow-up. However, it has been proposed that forced expiratory flow at 25‐75% (FEF_25‐75) could be more sensitive than FEV₁ to detect slight airways obstruction. In this regard, a cutoff FEF_25‐75 value has been recently established in a group of asthmatic children: FEF_25‐75 < 65% of predicted has been considered impaired. However, the considered population was specifically selected. Therefore, the aim of the present study was to confirm an FEF_25‐75 cutoff value in a large cohort of asthmatic children. Seven hundred allergic children (493 male subjects; median age, 11 years) with controlled and partly controlled asthma were evaluated by performing spirometry and skin-prick tests. Three hundred thirteen (44.7%) patients had FEF_25‐75% values of <65% of predicted. Two predictors were significantly associated with impaired FEF_25‐75 values: (i) sensitization to perennial allergens (adjusted odds ratio [OR_Adj], 3.4) and (ii) FEV₁ ≤ 86% of predicted (OR_Adj, 3.8). This study, conducted in real life, could suggest that FEF_25‐75 value of <65% of predicted may be considered abnormal.