Association between ambient fine particulate matter and adult outpatient visits for rheumatoid arthritis in Beijing, China

The association between fine particulate matter (PM2.5) and rheumatoid arthritis (RA) is currently unclear, especially in Beijing, a city with severe air pollution. Our study aimed to explore the relationship between short-term outdoor exposure to PM2.5 and RA outpatient visits using a time-series analysis in Beijing. We used the Beijing's Medical Claims for Employees database to identify patients with RA in 2010-2012. A generalized additive model with a Poisson link was used to estimate the percentage change in RA outpatient visits after the PM2.5 concentration increased by 10 mu g/m(3). From January 1, 2010, to June 30, 2012, a total of 541,061 RA outpatient visits were identified. During the study period, the average daily (standard deviation) concentration of PM2.5 was 99.5 (75.3) mu g/m(3). A 10 mu g/m(3) increase in PM2.5 concentration was correlated with a 0.21% (95% CI, 0.18-0.23%) increase in outpatient visits for RA on the same day. A significant association for the cumulative effect of PM2.5 was found, and the largest significant association was observed for a lag of 0-3 days (0.26%; 95% CI, 0.23-0.29%). Stratified analyses revealed that females (0.29%, 95% CI: 0.26-0.33%) and 18-65 years old patients (0.29%, 95% CI: 0.25-0.32%) were most susceptible to the effects of PM2.5 exposure. The current findings showed that short-term exposure to PM2.5 was followed by an increase in the number of outpatient visits for RA in Beijing. Future studies should investigate the mechanisms underlying this association.

Automated summary

This study aimed to explore the relationship between short-term exposure to fine particulate matter (PM2.5) and rheumatoid arthritis (RA) outpatient visits in Beijing. The results showed that short-term exposure to PM2.5 was associated with an increase in RA outpatient visits, and this association had a lag effect. Females and patients aged 18-65 years were most susceptible to the effects of PM2.5 exposure.