Systemic onset juvenile idiopathic arthritis and exposure to fine particulate air pollution.
OBJECTIVE
Fine particulate matter (PM2.5) is a measurable component of ambient pollution, and positive associations of short-term PM2.5 exposure with the clinical presentation of systemic onset juvenile idiopathic arthritis (SJIA) in young children have been described in a regional cohort. Our objective was to further establish associations between short-term pollution exposures and the reported clinical event of SJIA onset in cases residing from multiple metropolitan regions.


METHODS
A case-crossover study design was used to analyse associations of short-term PM2.5 exposures with the event of SJIA symptom onset from cases residing in five metropolitan regions. Time trends, seasonality, month, and weekday were controlled for by matching. Selected exposure windows (to 14 days) of PM2.5 were examined.


RESULTS
Positive, statistically significant associations between PM2.5 concentrations and elevated risk of SJIA were not observed. The most positive associations of short-term PM2.5 exposure with SJIA were in children <5.5 years (RR 1.75, 95% CI 0.85-3.62). An ad hoc extended pooled analysis including previously reported cases from Utah's metropolitan areas identified an increased risk of SJIA for children <5.5 years (RR = 1.76, 95% CI 1.07-2.89 per 10 μg/m3 increase in 3-day lagged moving average PM2.5).


CONCLUSIONS
In this multi-city, multi-period study small, statistically insignificant PM2.5-SJIA associations are observed. However, as found in prior study, the PM2.5-SJIA association is most suggestive in preschool aged children. Larger numbers of SJIA cases spatially located in geographic areas which experience a greater day to day ambient particulate burden may be required by the analysis to demonstrate effects.
Pediatric Rheumatology, The Cleveland Clinic, Cleveland, OH, USA. zefta@ccf.org.
Andrew S
AS
Zeft
Emory University School of Medicine, Atlanta, USA.
Sampath
S
Prahalad
University of Toronto, Hospital for Sick Children, Toronto, Canada.
Rayfel
R
Schneider
Harvard University, Boston Children's Hospital, MA, USA.
Fatma
F
Dedeoglu
University of Pennsylvania, Children's Hospital Philadelphia, PA, USA.
Pamela F
PF
Weiss
University of Cincinnati Medical Center; Cincinnati Children's Hospital, OH, USA.
Alexei A
AA
Grom
Brigham Young University, Provo, UT, USA.
Carter
C
Mix
Brigham Young University, Provo, UT, USA.
C Arden
CA
Pope Rd
D000367:Age Factors; D000393:Air Pollutants / Q000009:adverse effects*; D001171:Arthritis, Juvenile / Q000139:chemically induced* / Q000175:diagnosis / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D004781:Environmental Exposure / Q000009:adverse effects*; D005260:Female; D006801:Humans; D008297:Male; D009864:Ontario / Q000453:epidemiology; D010316:Particle Size; D052638:Particulate Matter / Q000009:adverse effects*; D018570:Risk Assessment; D012307:Risk Factors; D012621:Seasons; D013997:Time Factors; D014481:United States / Q000453:epidemiology; D014504:Urban Health
D000393:Air Pollutants; D052638:Particulate Matter