Longitudinal lung function in urban firefighters: A group-based multi-trajectory modelling approach

Area of Science:

• Occupational Health
• Pulmonary Medicine
• Epidemiology

Background:

• Firefighters face physical and chemical hazards impacting lung health.
• The long-term effects of chronic exposure and acute insults on firefighter spirometry are not well understood.

Purpose of the Study:

• To identify distinct spirometry trajectories in firefighters.
• To investigate associations between these trajectories and demographic, lifestyle, and occupational factors.

Main Methods:

• Utilized group-based multi-trajectory modeling (GBMTM) on six waves of data from South Australian Metropolitan Fire Service Study (2007-2019).
• Analyzed spirometry parameters including Forced Expiratory Volume in 1 second (FEV1) and Forced Vital Capacity (FVC) z-scores.
• Assessed differences in baseline characteristics across identified trajectory groups using ANOVA and chi-square tests.

Main Results:

• Identified five distinct spirometry trajectories (three stable, two declining) among 669 firefighters.
• Found significant associations between trajectory group membership and body mass index (BMI) and respiratory health.
• No significant differences were observed in relation to years of service, respiratory protection use, or smoking history.

Conclusions:

• Group-based multi-trajectory modeling effectively defined distinct spirometry trajectories in firefighters.
• Lung function trajectories are linked to BMI and respiratory conditions, but not traditional occupational or smoking factors.