Association between small airway dysfunction and cardiac conditions: a Swiss urban population cross-sectional study.

Introduction: Small airway dysfunction (SAD) may be an early sign of cardiopulmonary overload due to small airway mucosal thickening or be related to the oxidative stress characteristic of cardiovascular diseases. A high prevalence of SAD coexisting with chronic heart failure may be associated with an increase in all-cause mortality. We analysed the association between SAD and cardiac conditions in the PneumoLaus study. Methods: PneumoLaus is based on the Swiss general urban population cohort CoLaus|PsyCoLaus. SAD was defined by maximal mid-expiratory flow (MMEF) before bronchodilatation <65% predicted or MMEF<lower limit of normal (LLN) based on GLI-2012. Self-reported cardiac events were defined as new occurrence of any cardiac condition since baseline analysis (approximately 10 years before spirometry). Adjudicated cardiac conditions correspond to the confirmed diagnosis in the local medical record. We performed analyses with SAD criteria adjusted for age, sex, smoking duration, smoking status and body mass index (model 1). A second model was additionally adjusted for N-terminal pro-brain natriuretic peptide (NT-proBNP). Results: Among 3342 subjects that underwent spirometry, 473 (14.2%) reported a new cardiac condition. SAD defined as MMEF<65% predicted or MMEF<LLN was associated with self-reported cardiac conditions (OR 1.38, 95% CI 1.05-1.82 and OR 1.60, 95% CI 1.07-2.40) for model 1). This association persisted for SAD defined MMEF<LLN after adjustment for NT-proBNP. Adjudicated cardiac conditions were associated with SAD (defined as MMEF<LLN) in the unadjusted model and in model 1 (OR 1.85, 95% CI 1.05-3.27). Conclusions: SAD defined as MMEF<LLN was associated with self-reported and adjudicated cardiac conditions.