Prevalence of small airway dysfunction in the Swiss PneumoLaus Cohort

Abstract

Background Recent evidence identified exposure to particulate matter of size ⩽2.5 µm (PM2.5) as a risk factor for high prevalence of small airway dysfunction (SAD). We assessed the prevalence of SAD in a European region with low air pollution levels. Methods SAD was defined as a maximum mid-expiratory flow (MMEF) <65% of predicted value (PV) or MMEF <65% PV in 425 (12.7%) and MMEF <65% PV and MMEF <65% PV was observed for individuals aged >65 years only. In an area where ambient PM2.5 concentration was <15 µg·m−3 during the observation period (2010 and 2020), ⩾72% of participants with SAD were ever-smokers. Conclusions The observed low prevalence of SAD of 5.0–12.7% depending on criteria employed may be related to lower PM2.5 exposure. Smoking was the main factor associated with SAD in an area with low PM2.5 exposure. Employing a MMEF threshold <65% PV carries a risk of SAD overdiagnosis in elderly individuals.