Abstract
Background Chronic obstructive pulmonary disease (COPD) is diagnosed and its severity graded by traditional spirometric parameters (forced expiratory volume in 1 s (FEV1)/forced vital capacity (FVC) and FEV1, respectively) but these parameters are considered insensitive for identifying early pathology. Measures of small airway function, including forced expiratory flow between 25% and 75% of vital capacity (FEF25-75), may be more valuable in the earliest phases of COPD. This study aimed to determine the prevalence of low FEF25-75 in ever-smokers with and without airflow limitation (AL) and to determine whether FEF25-75 relates to AL severity.
Method A retrospective analysis of lung function data of 1458 ever-smokers suspected clinically of having COPD. Low FEF25-75 was defined by z-score
Results Low FEF25-75 was present in 99.9% of patients with AL, and 50% of those without AL. Patients in the low FEF25-75/AL− group had lower spirometric measures (including FEV1 FEF25-75/FVC and FEV3/FVC) than those in the normal FEF25-75/AL− group. FEF25-75 decreased with AL severity. A logistic regression model demonstrated that in the absence of AL, the presence of low FEF25-75 was associated with lower FEV1 and FEV1/FVC even when smoking history was accounted for.
Conclusions Low FEF25-75 is a physiological trait in patients with conventional spirometric AL and likely reflects early evidence of impairment in the small airways when spirometry is within the ‘normal range’. FEF25-75 likely identifies a group of patients with early evidence of pathological lung damage who warrant careful monitoring and reinforced early intervention to abrogate further lung injury.
Data availability statement
Data are available on reasonable request. The lung function data used and evaluated during this study can be made available from the corresponding author, NYA, on reasonable request.
Method A retrospective analysis of lung function data of 1458 ever-smokers suspected clinically of having COPD. Low FEF25-75 was defined by z-score
Results Low FEF25-75 was present in 99.9% of patients with AL, and 50% of those without AL. Patients in the low FEF25-75/AL− group had lower spirometric measures (including FEV1 FEF25-75/FVC and FEV3/FVC) than those in the normal FEF25-75/AL− group. FEF25-75 decreased with AL severity. A logistic regression model demonstrated that in the absence of AL, the presence of low FEF25-75 was associated with lower FEV1 and FEV1/FVC even when smoking history was accounted for.
Conclusions Low FEF25-75 is a physiological trait in patients with conventional spirometric AL and likely reflects early evidence of impairment in the small airways when spirometry is within the ‘normal range’. FEF25-75 likely identifies a group of patients with early evidence of pathological lung damage who warrant careful monitoring and reinforced early intervention to abrogate further lung injury.
Data availability statement
Data are available on reasonable request. The lung function data used and evaluated during this study can be made available from the corresponding author, NYA, on reasonable request.
| Original language | English |
|---|---|
| Article number | e001385 |
| Journal | BMJ Open Respiratory Research |
| Volume | 9 |
| Issue number | 1 |
| DOIs | |
| Publication status | Published - 6 Oct 2022 |
Keywords
- COPD epidemiology
- Lung Physiology
- Respiratory Measurement
ASJC Scopus subject areas
- Pulmonary and Respiratory Medicine