Association of ambient air pollution with incident rheumatoid arthritis, subsequent respiratory diseases, and death: A multi-state analysis of a prospective cohort

Background

Previous studies have mostly examined the separate effects of air pollution exposure on the onset of rheumatoid arthritis (RA) or respiratory diseases. However, no studies have further explored the impact of air pollution on the progression from a baseline healthy population to the onset of RA, followed by the further complication of respiratory diseases and, ultimately, mortality.

Methods

Based on data from the UK Biobank, we included 340,485 participants without RA or respiratory diseases. Air pollution exposure levels were estimated by land use regression modeling, and multi-state modeling was used to assess the impact of air pollution on RA disease progression trajectories.

Results

During a median follow-up of 12.66 years, 3650 participants developed RA, of whom 553 subsequently developed respiratory diseases; 24,016 participants died during this process. We observed that PM_2.5, NO₂, and NO_x exposures adversely affected the development of RA, with PM_2.5 and NO₂ exposures contributing to the subsequent development of respiratory diseases. Furthermore, all four air pollutants were associated with increased mortality risk. Notably, PM_2.5 and NO₂ demonstrated the strongest effects on the transition from RA to death, with hazard ratios (HRs) per interquartile range (IQR) increase of 1.21 (95 % CI: 1.06–1.37) and 1.20 (95 % CI: 1.05–1.37), respectively. However, no significant effect of air pollution was observed on the further progression from respiratory diseases complicating RA to death.

Conclusion

Our findings suggest that air pollution abatement may help prevent the onset of RA as well as its further progression.