Introduction
Atopic dermatitis (AD) is a chronic relapsing inflammatory skin disease
with peak incidence in the first 2 years of life 1. It
affects approximately 8.4 million children (<18 years) in the
US , with 1 in 3 AD cases exhibiting moderate to severe forms of disease2. Moreover, children with severe AD exhibit lower
quality of life 3 and higher risk of comorbid chronic
health conditions, such as asthma and allergic rhinitis, compared to
mild AD, in addition to a two-fold higher healthcare utilization4. Early childhood caries (ECC), a chronic
diet-mediated oral infectious disease, affecting approximately 12.4
million children (<18 years) 5, is ranked
fifth amongst the top 30 global health conditions in terms of incidence
rates 6. Although two large-scale cross-sectional
studies in 0-17 year old American (N=79,667) 4 and
6-15 year old Japanese children (N=21,792) 7 reported
no association between allergic diseases (including AD) and dental
caries, our previous study using a longitudinal study design revealed a
potential link with higher ECC risk at 2- and 3-years in infants with
atopic dermatitis 8. However, validity of the
diagnostic criteria employed previously and effect of clinical severity
on the AD-ECC link remains unknown.
Large-scale population studies often employ caregiver-reported 1-year
history of a doctor-diagnosed AD as a proxy measure to estimate AD
prevalence in children 9, which has been reported to
render low sensitivity (70%) in identifying AD in 0-17 year old
children 10. As more than two-thirds of infants with
moderate-to-severe forms of AD demonstrate allergic sensitization in the
first 2 years of life 11, our previous study
supplemented the caregiver-reported history with a positive skin prick
test (SPT) for identification of AD 8. Nevertheless,
use of SPT in AD diagnosis has not been validated yet. Furthermore,
children with severe AD have been associated with poor oral
hygiene/dietary control possibly due to a distraction by symptoms and
management of AD 12; however the regression model
testing the previous AD-ECC link did not account for these behavioural
factors. Hence, the current study aimed to investigate if clinical
severity of AD by 3 years is associated with increased ECC risk among
3-year old children with/without control of potential
dietary/behavioural confounders. Additionally, diagnostic accuracy of
caregiver-reported history of doctor-diagnosed AD, with/without SPT, was
evaluated using physician diagnosis as the gold standard.