Patients with systemic lupus erythematosus may modify the association between exposure to particles and the risk of chronic obstructive pulmonary disease: a nested case-control study

Abstract

Introduction. Due to a possible shared etiology between systemic lupus erythematosus (SLE) and chronic obstructive pulmonary disease (COPD), SLE patients may be a susceptible group that could exacerbate the risk of COPD development due to exposure to air pollution. However, no study has examined the association between air pollution and COPD in the subgroup of individuals with and without SLE. Methods. We conducted a nested case-control study in Taiwan. Individuals who aged 20 to 60 years were retrieved from the longitudinal health insurance database 2000 during 2001-2010. Cases were defined as individuals who received at least two consistent diagnoses of COPD. For each case, we randomly selected ten controls (1:10) and individual matched by date of birth (within 1 year), sex, and index date. The SLE patients were defined as individuals received diagnoses of SLE before the index date of COPD. Inverse distance weighting method was used to generate exposure surface of carbon monoxide (CO), nitrogen dioxide (NO2), ozone (O3), particles with aerodynamic diameter less than 10 μm (PM10) and sulfate dioxide (SO2). The effect of each pollutant for COPD was estimated by conditional logistic regression as the odds ratio (OR) and 95% confidence interval (CI) per 100-ppb change for CO, 10-ppb change for NO2 and O3, 10-μg/m3 change for PM10, and 1-ppb change for SO2. Results. There were 28,188 incident COPD cases were matched with 281,880 controls from the source population of 564,841 individuals during 2001-2010. The adjusted OR for COPD per 10-ppb increase in PM10 level was 1.36 (95% CI: 1.10, 1.67) for individuals with SLE and 1.05 (95% CI: 1.04, 1.06) for individuals without SLE (p for interaction=0.011). Conclusions. These results suggest that patients with SLE and exposure to particles are more likely to development of COPD.