To investigate the association between exposure to air pollutants in the Sao Paulo metropolitan area and disease activity in juvenile-onset systemic lupus erythematosus (SLE) patients.
A longitudinal panel study based on 409 consecutive visits of juvenile-onset SLE patients living in the Sao Paulo metropolitan area was carried out. Disease activity was evaluated in accordance with the Systemic Lupus Erythematosus Disease Activity Index 2000 (SLEDAI-2K), and the patients were divided into 2 groups: those with SLEDAI scores ≤8 and those with SLEDAI scores >8. Daily concentrations of inhaled particulate matter (PM10 ), sulfur dioxide, nitrogen dioxide (NO2 ), ozone, and carbon monoxide (CO) were evaluated on the 21 days preceding the medical visits. A generalized estimation equation model was used to assess the impact of these measurements on SLEDAI-2K scores, considering the fixed effects for repetitive measurements. The models were adjusted for erythrocyte sedimentation rate, corticosteroid use (daily and cumulative doses), antimalarial use, the use of immunosuppressive agents, the presence of infection 20 days preceding the medical appointment, and the minimum temperature and relative humidity outdoors.
PM10 , NO2 , and CO were risk factors for juvenile-onset SLE disease activity (SLEDAI-2K score >8) approximately 2 weeks after exposure. A 13.4 μg/m(3) increase in the PM10 moving average (from lag 12 to lag 15) was associated with a 34% increase (95% confidence interval 7.0-68.0) in the risk of a SLEDAI-2K score >8.
This is the first study to show that exposure to inhaled pollutants may increase the risk of disease activity in children with juvenile-onset SLE in a large urban center.