The question addressed by the study
Small airway collapse during expiration, known as expiratory flow limitation (EFL), can be
detected using oscillometry and is associated with worse clinical outcomes in chronic
obstructive pulmonary disease (COPD).
This study investigated the prevalence of EFL in a cohort of highly symptomatic patients,
evaluated clinical and lung function characteristics of patients with EFL and studied the
repeatability of EFL over 6 months.
Materials/patients and methods
Seventy patients were recruited. Clinical characteristics and lung function metrics were
collected at baseline and 6 months. Impulse oscillometry (IOS) was used to detect presence of
EFL. Patients were defined as EFLHigh (ΔX5 ≥0.28 kPa/L/s); EFLIntermediate (ΔX5 0.1-
0.27kPa/L/s) and EFLNone (ΔX5 <0.1 kPa/L/s).
EFLHigh was present in 47.8% of patients at baseline. ΔX5 showed excellent repeatability over
6 months (rho = 0.78, p<0.0001, ICC = 0.88), with the best repeatability observed in EFLNone
and EFLHigh patients (ICC = 0.77 and 0.65 respectively). Compared to EFLNone patients, EFLHigh
had a higher BMI, worse health-related quality of life and increased peripheral airway
resistance. EFLIntermediate was more variable over time with less severe physiological
Answer to the question
Overall, these data indicate that EFLHigh is a common, and relatively stable, component of
disease pathophysiology in highly symptomatic COPD patients. EFLHigh was also associated
with worse quality of life and obesity.