Are children with sickle cell disease at particular risk from the
harmful effects of air pollution? Evidence from a large,
urban/peri-urban cohort.
Abstract
Introduction Pathophysiologic pathways of sickle cell disease (SCD) and
air pollution involve inflammation, oxidative stress, and endothelial
damage. It is therefore plausible that children with SCD are especially
prone to air pollution’s harmful effects. Methods Patient data were
collected from a single center, urban/peri-urban cohort of children with
confirmed SCD. Daily ambient concentrations of particulate matter (PM
2.5) were collected via satellite-derived remote-sensing
technology, and carbon monoxide (CO), nitrogen dioxide (NO
2), and ozone from local monitoring stations. We used
multivariable regression to quantify associations of pollutant levels
and daily counts of emergency department (ED) visits, accounting for
weather and time trends. For comparison, we quantified the associations
of pollutant levels with daily all-patient (non-SCD) ED visits to our
center. Results From 2010-2018, there were 17 731 ED visits by 1740
children with SCD (64.8% HbSS/HbSβ 0). Vaso-occlusive
events (57.8%), respiratory illness (17.1%), and fever (16.1%) were
the most common visit diagnoses. Three-day (lags 0-2) rolling mean PM
2.5 and CO levels were associated with daily ED visits
among those with SCD (PM 2.5 incident rate ratio (IRR)
1.051 (95% CI 1.010-1.094) per 9.4 µg/m 3 increase;
CO 1.088 (1.045-1.132) per 0.5 ppm). NO 2 showed
positive associations in secondary analyses; ozone levels were not
associated with ED visits. The comparison, all-patient ED visit analyses
showed lower IRR for all pollutants. Conclusions Our results suggest
short-term air pollution levels as triggers for SCD events and that
children with SCD may be more vulnerable to air pollution than those
without SCD. Targeted pollution-avoidance strategies could have
significant clinical benefits in this population.