Association of Particulate Matter with Autoimmune Rheumatic Diseases among Adults in South Korea.

OBJECTIVE The primary objective is to investigate adverse effects of ambient particulate matter (PM) in various size on the incidence of prevalent autoimmune rheumatic diseases (AIRDs): Rheumatoid Arthritis (RA), Ankylosing Spondylitis (AS), and Systemic Lupus Erythematosus (SLE). METHODS We investigated 230,034 participants in three metropolitan cities of South Korea from the National Health Insurance Service-National Sample Cohort (NHIS-NSC). Starting from January 2010, subjects were followed up until the first event of prevalent AIRDs, death, or December 2013. 2008-2009 respective averages of PM2.5 (< 2.5μm) and PMcoarse (2.5μm to 10μm) were linked with participants' administrative district codes. Adjusted hazard ratios (aHRs) and 95% confidence intervals (CIs) were estimated using Cox regression analysis in one- and two-pollutant model. RESULTS Adjusted for age, sex, region, and household income in two-pollutant model, RA incidence was positively associated with 10μg/m³ increment of PM2.5 (aHR = 1.74, 95% CI: 1.06-2.86), but not with PMcoarse (aHR = 1.27, 95% CI: 0.87-1.85). In one-pollutant model, an elevated incidence rate of RA was slightly attenuated (PM2.5 aHR = 1.61, 95% CI: 0.99-2.61; PMcoarse aHR = 1.13, 95% CI: 0.80-1.61), with marginal statistical significance of PM2.5. RA incidence was also higher in 4th quartile group of PM2.5 compared to 1st quartile group (aHR = 1.83, 95% CI: 1.07-3.11). No adverse effects of PM were found on AS or SLE in one- and two-pollutant models. CONCLUSION Important components of PM10 associated with RA incidence were fine fractions (PM2.5), while no positive association was found between PM and AS or SLE.