Prevalence of small airway dysfunction in the Swiss PneumoLaus Cohort

Brice Touilloux; Cedric Bongard; Benoit Lechartier; Minh Khoa Truong; Pedro Marques-Vidal; Peter Vollenweider; Julien Vaucher; Alessio Casutt; Christophe von Garnier

doi:10.1183/23120541.00381-2023

Prevalence of small airway dysfunction in the Swiss PneumoLaus Cohort

ERJ Open Res. 2023 Sep 11;9(5):00381-2023. doi: 10.1183/23120541.00381-2023. eCollection 2023 Sep.

Authors

Brice Touilloux^{1

2}, Cedric Bongard¹, Benoit Lechartier¹, Minh Khoa Truong¹, Pedro Marques-Vidal³, Peter Vollenweider³, Julien Vaucher^{3

4

5}, Alessio Casutt^{1

6

7}, Christophe von Garnier^{1

7}

Affiliations

¹ Division of Pulmonology, Department of Medicine, Lausanne University Hospital (CHUV) and University of Lausanne (UNIL), Lausanne, Switzerland.
² Division of Pulmonology, Department of Medicine and Specialties, Fribourg Hospital, Fribourg, Switzerland.
³ Division of Internal Medicine, Department of Medicine, CHUV and UNIL, Lausanne, Switzerland.
⁴ Division of Internal Medicine, Department of Medicine and Specialties, Fribourg Hospital, Fribourg, Switzerland.
⁵ University of Fribourg, Fribourg, Switzerland.
⁶ Division of Pneumology, Ospedale Regionale di Lugano, Ente Ospedaliero Cantonale, Lugano, Switzerland.
⁷ These authors contributed equally.

Abstract

Background: Recent evidence identified exposure to particulate matter of size ≤2.5 µm (PM_2.5) 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 <lower limit of normal (LLN) measured by spirometry in the Swiss PneumoLaus cohort. We performed bivariate and multivariable analysis with MMEF criteria, age, sex, body mass index, respiratory symptoms and smoking status. Mean PM_2.5 values were obtained from a Swiss national database.

Results: Among 3351 participants (97.6% Caucasian, 55.7% female sex, mean age 62.7 years), we observed MMEF <65% PV in 425 (12.7%) and MMEF <LLN in 167 (5.0%) individuals. None of the participants had both MMEF <LLN and ≥65% PV. MMEF <65% PV and MMEF <LLN were significantly associated with age, smoking status, cough, sputum and dyspnoea, whereas a positive association with MMEF <65% PV was observed for individuals aged >65 years only. In an area where ambient PM_2.5 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 PM_2.5 exposure. Smoking was the main factor associated with SAD in an area with low PM_2.5 exposure. Employing a MMEF threshold <65% PV carries a risk of SAD overdiagnosis in elderly individuals.