Are prematurity and environmental factors determinants for developing childhood-onset systemic lupus erythematosus?

OBJECTIVE

The objective of this study is to evaluate the influence of exposure to air pollutants and inhalable environmental elements during pregnancy and after birth until childhood-onset systemic lupus erythematosus(cSLE) diagnosis.

METHODS

This case-control study comprised 30 cSLE patients and 86 healthy controls living in the Sao Paulo metropolitan area. A structured and reliable questionnaire (kappa index for test-retest was 0.78) assessed demographic data, gestational and perinatal-related-factors, and exposure to inhalable elements during pregnancy and after birth (occupational exposure to inhalable particles and/or volatile vapor, and/or tobacco, as well as, the presence of industrial activities or gas stations near the home/work/daycare/school). Tropospheric pollutants included: particulate matter (PM10), sulfur dioxide (SO2), nitrogen dioxide (NO2), ozone (O3) and carbon monoxide (CO).

RESULTS

The median current age was similar between cSLE patients and healthy controls [16.0 (5-21) versus 15.0 (4-21) years, p = .32], likewise the frequency of female gender (87% versus 78%, p = .43). The frequencies of prematurity (30% versus 6%, p = .001), maternal occupational exposure during pregnancy (59% versus 12%, p < .001), exposure to volatile vapor (48% versus 8%, p < .001) and fetal smoking (maternal and/or secondhand) (37% versus 19%, p = .008) were significantly higher in cSLE patients compared with controls. In a multivariate analysis regarding the gestation period, maternal occupational exposure (OR 13.5, 95% CI 2.5-72.4, p = .002), fetal smoking (OR 8.6, 95%CI 1.6-47, p = .013) and prematurity (OR 15.8, 95%CI 1.9-135.3, p = .012) remained risk factors for cSLE development. Furthermore, exposure to secondhand smoking during pregnancy and after birth (OR 9.1, 95%CI 1.8-42.1, p = .002) was also a risk factor for cSLE development.

CONCLUSIONS

Prematurity and environmental factors were risk factors for developing cSLE.