Long-term variability of impulse oscillometry and spirometry in stable COPD and asthma

Area of Science:

• Pulmonary Medicine
• Respiratory Physiology
• Diagnostic Techniques

Background:

• Optimizing spirometry for lung function labs presents challenges.
• Long-term variability between impulse oscillometry (IOS) and spirometry in stable COPD and asthma remains unclear.
• The forced oscillation technique (IOS) is increasingly used in routine lung function testing.

Purpose of the Study:

• To determine the long-term variability of IOS parameters between clinic visits in stable COPD and asthma patients.
• To assess the relationship between IOS parameters' long-term variability and COPD severity.

Main Methods:

• Utilized data from 73 stable COPD and 119 stable asthma patients with at least three clinic visits.
• Calculated standard deviation (SDbv), coefficient of variation (COV), intraclass correlation coefficient (ICC), and coefficient of repeatability (COR).
• Employed statistical tests including Wilcoxon Mann-Whitney, Kruskal Wallis, Bonferroni, Spearman correlation, and multiple regression analyses.

Main Results:

• IOS resistance parameters demonstrated high repeatability (ICC > 0.8) in both COPD and asthma groups, outperforming IOS reactance parameters.
• Spirometry parameters exhibited lower repeatability (ICC < 0.8) compared to IOS resistance parameters, with worsening repeatability in higher GOLD stages of COPD.
• Airflow obstruction severity correlated with the long-term variability of R5 (resistance at 5 Hz) in GOLD 4 COPD patients.

Conclusions:

• IOS resistance parameters offer good long-term repeatability in patients with asthma and COPD.
• Spirometry parameter repeatability is inferior to that of IOS resistance parameters across varying stages of COPD severity.