Risk Factors Associated with Juvenile Idiopathic Arthritis: Exposure to Cigarette Smoke and Air Pollution from Pregnancy to Disease Diagnosis.

Abstract

To evaluate exposure to environmental factors inhaled during pregnancy and after birth until juvenile idiopathic arthritis (JIA) diagnosis among residents of a large city. This is an exploratory case-control study that consists of 66 patients with JIA and 124 healthy controls matched by age and sex, living in the São Paulo, Brazil, metropolitan area until JIA diagnosis, and whose mothers had resided in this region during pregnancy. A structured and reliable questionnaire (κ index for test-retest was 0.80) assessed demographic data, gestational and perinatal-related factors, and exposure to inhalable environmental elements during pregnancy and after birth (occupational exposure to inhalable particles and/or volatile vapor, exposure to cigarette smoke, and the presence of industrial activities or gas stations near the home, work, daycare, or school). Tropospheric pollutants included particulate matter (PM₁₀), sulfur dioxide (SO₂), nitrogen dioxide (NO₂), ozone (O₃), and carbon monoxide (CO). During pregnancy, intrauterine cigarette smoke exposure (OR 3.43, 95% CI 1.45-8.12, p = 0.005) and maternal occupational exposure (OR 13.69, 95% CI 4.4-42.3, p < 0.001) were significant independent risk factors for JIA diagnosis. In contrast, maternal employment (OR 0.06, 95% CI 0.02-0.2, p < 0.001) and ideal maternal weight gain (OR 0.36, 95% CI 0.2-0.8, p = 0.017) presented negative associations. Secondhand smoke exposure from birth to JIA diagnosis (OR 3.6, 95% CI 1.8-7.3, p < 0.001) and exposure to O₃ during the second year of life (OR 2.76, 95% CI 1.20-6.37, p = 0.017) were independent and significant risk factors for the pathogenesis of JIA. In our study, cigarette smoke exposure (intrauterine and after birth), exposure to O₃ in the second year of life, and maternal occupational exposure were identified as potential risk factors for JIA, warranting further study.