Association between CCL18 levels and the development of asthma
and sensitisation
Proceeding with the chemokines showing the strongest consistent
associations cross-sectionally, we set up GEE models studying each
chemokine at each age separately in relation to various intervals of
asthma and sensitisation development to study longitudinal relationships
over time. These models take into account correlations within
individuals, and as the data are not independent over time, this
provides an advantage of running both the GEE and logistic regression
models. Consistent longitudinal patterns were only revealed for
circulating levels of CCL18 at ages 1 and 8 (Figure 5).
Asthma: In a longitudinal model including information on asthma
from four time-points (ages 5, 8, 11 and 16), we observed a significant
association between increasing CCL18 levels at age 1 year and the higher
risk of asthma from early school age to adolescence (OR=2.9, 95% CI
1.1-7.6, p=0.028). Similarly, higher CCL18 levels at ages 1 (OR=3.5,
95% CI 1.3-9.8, p=0.01) and 8 years (OR=3.0, 95% CI 1.6-5.9, p=0.001)
were associated with an increased risk of asthma between ages 8 and 16
years.
Sensitisation: In a longitudinal model including information on
SPTs from five time-points (ages 3-16 years), the odds of becoming
sensitised increased significantly with increased CCL18 concentrations
at age 1 (OR=3.1, 95% CI 1.2-8.3, p=0.022). Similarly, the odds ratios
for developing sensitisation between the ages 8 and 16 years increased
significantly with increasing CCL18 levels at ages 1 (OR=3.5, 95% CI
1.3-9.9, p=0.018) and 8 years (OR=3.0, 95% CI 1.5-5.9, p=0.002).