Health-related quality of life (HRQL) is associated with small airway dysfunction (SAD) in mild COPD and smokers at risk – cross-sectional baseline data from CAPTO-COPD

Abstract

<b>Background:</b> Severe COPD is associated with significant impairment in HRQL. Typical symptoms can be already present early despite normal spirometry. This is attributable to SAD for which currently used tests are insensitive. We aimed to assess the impact of SAD on HRQL in symptomatic (ex)-smokers and mild COPD using advanced lung function testing. <b>Methods:</b> We included 152 patients (age 63±10y) with mild COPD (n=90, post-bronchodilator FEV₁/VC&lt;70% + FEV₁≥70%pred) or (ex)-smokers at risk (n=62 FEV₁/VC≥70%, ≥10 pack years + CAT ≥10 or long-acting bronchodilator) in the CAPTO-COPD longitudinal observational study. Conventional lung function testing included spirometry, body plethysmography and TLCO. Airwave oscillometry and SF₆-multiple breath washout (MBW) were additionally performed. SGRQ-c separated subjects with better (&lt;25) or worse (≥25) HRQL. <b>Results:</b> Mean FEV₁ was 82±14%pred, RV/TLC 126±19%pred and TLCO 78±16%pred. Abnormal lung function parameters (ULN or LLN) were found in up to 60% of patients using advanced measurements (AX) and about 40% using conventional measurements (FEV₁, TLCO). Mean SGRQ total score was 25.3±15.3. Meaningful differences between better or worse HRQL were found for SAD parameters (AX, FDR and S_cond) as well as central obstruction (FEV₁). Effects were most pronounced for peripheral resistance (FDR, p=0.03) and elastic properties (AX p=0.06). <b>Conclusion:</b> SAD is associated with an impairment in HRQL even in symptomatic (ex)-smokers and mild COPD underlining the clinical relevance of this lung functional abnormality.