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FEF25-75% Is a More Sensitive Measure Reflecting Airway Dysfunction in Patients with Asthma: A Comparison Study Using
Rundong Qin1, Jiaying An2, Jiaxing Xie1
1Department of Allergy and Clinical Immunology, State Key Laboratory of Respiratory Disease, National Clinical Researcher Center for Respiratory Disease, Guangzhou Institute of Respiratory Health, the First Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong, P.R. China.
Background:
Reduced forced expiratory flow between 25% and 75% of vital capacity percent predicted (FEF25-75%) representing small airway dysfunction (SAD) was associated with asthma development and progression.
Objective:
To investigate whether FEF25-75% was superior to forced expiratory volume in 1 second in predicted (FEV1%) in reflecting asthma features in adult patients.
Methods:
A retrospective spirometry dataset comprising 1801 adult patients with confirmed asthma and a subgroup of 332 patients having detailed clinical data were used to explore the association of FEF25-75% and/or FEV1% with clinical features of asthma.
Results:
Of the 1801 subjects, FEV1% and FEF25-75% ranged from 136.8% to 10.2% and 127.3% to 3.1%, respectively. FEF25-75% < 65% was present in 1,478 (82.07%) of patients. FEF25-75% was strongly correlated with matched FEV1% (r = 0.900, P < .001). FEF25-75% and FEV1% were both correlated with airway hyperresponsiveness (r = 0.436, P < .001; r = 0.367, P < .001), asthma control test score (r = 0.329, P < .001; r = 0.335, P < .001), and sputum eosinophil count (r = -0.306, P < .001; r = -0.307, P < .001). Receiver-operating characteristic curves showed that FEF25-75% had greater value in predicting severe asthma (area under the curve: 0.84 vs 0.81, P = .018), airflow obstruction (0.97 vs 0.89, P < .001), and severe bronchial hyperresponsiveness (0.74 vs 0.69, P = .012) as compared with FEV1%. Patients with SAD (FEF25-75% < 65%) in the presence of normal FEV1% exhibited higher sputum eosinophil counts and had an increased dosage of daily inhaled corticosteroids (P < .001 and P = .010) than patients with normal lung function and their FEF25-75% values correlated with sputum eosinophil count (r = -0.419, P = .015), but not FEV1%.
Conclusion:
FEF25-75% represented small airway function and was more sensitive at reflecting airway hyperresponsiveness, inflammation, and disease severity as compared with FEV1% in patients with asthma. Our data suggest further assessment of FEF25-75% in asthma management, particularly for those with SAD who present normal FEV1%.
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