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% (FEF25-75) could be more sensitive than FEV1 to detect slight airways obstruction. In this regard, a cutoff FEF25-75 value has been recently established in a group of asthmatic children: FEF25-75 < 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 FEF25-75 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 FEF25-75% values of <65% of predicted. Two predictors were significantly associated with impaired FEF25-75 values: (i) sensitization to perennial allergens (adjusted odds ratio [ORAdj], 3.4) and (ii) FEV1 ≤ 86% of predicted (ORAdj, 3.8). This study, conducted in real life, could suggest that FEF25-75 value of <65% of predicted may be considered abnormal