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Role of FEF25–75 in children sent by primary care paediatricians for asthma diagnosis

Spirometry is the goldstandard tool for detecting airflow limitation in asthma (www.ginas thma.org). Forced expiratory volume in 1 s (FEV1) and ratio between FEV1 and the forced vital capacity (FVC) are the most reliable marker of bronchial obstruction, although can be normal in some children despite inadequate asthma control.1 Conversely, the forced expiratory flow between 25% and 75% of vital capacity (FEF25– 75) could be a reliable marker for revealing airway impairment even when FEV1 and FEV1/FVC are normal. 2 An everincreasing body of evidence on FEF25– 75 reliability has been accumulating from 1972 to today. Impaired FEF25– 75 can reflect airway hyperresponsiveness, inflammation and disease severity more precisely than FEV1 in asthmatic adults and children. 3 Therefore, the current study aimed to investigate the practical role of FEF25– 75 in children sent by primary care paediatricians for confirming asthma diagnosis. This crosssectional study included children consecutively visited at a paediatric thirdlevel asthma clinic between January 2022 and March 2022. The inclusion criterion was the asthma diagnosis (www.ginas thma.org). The exclusion criteria were other respiratory diseases and infections, recent asthma exacerbation. The visit included history, clinical examination, spirometry, children's asthma control test (CACT) questionnaire and asthma control assessment proposed by GINA guidelines. The local Ethics Committee approved the study (code number: 22253/2017). Predictive values (ECCS 1993) and zscores (GLI 2012) of spirometry parameters were calculated.4 A univariate and multivariable logistic regression model was performed to detect factors significantly associated with impaired FEF25– 75. The significance level (αerror) was set at 0.05. SPSS v.24 was used for computation.