Discussion
Summary
We present a flowchart to aid the interpretation of dietary history and
skin prick test results from children with AD less than two years of
age. This tool is based on a consensus exercise with a
multi-disciplinary panel of clinicians with expertise in the management
of children with AD and/or food allergies. It is underpinned by advice
on which 12 or 7 symptoms to consider relevant to possible immediate or
delayed allergy respectively and which skin prick test thresholds to
regard as negative or sensitised. Consensus was reached for the use of
commercial reagents for wheat and soya but not which specific regents to
use for milk or egg skin prick tests.
Strengths and limitations
This is the first published attempt to use a formal consensus process to
agree what dietary advice should be given to parent of children with AD
based a given combination of dietary symptoms and skin prick tests
results to four foods, which are commonly allergenic or are suspected by
parents as causing their child’s AD symptoms. The exercise benefitted
from with perspective of clinicians from different disciplines, working
in generalist and specialist care. Panellist engagement was high, frank
views were shared and anonymity was retained until the workshop.
A consensus exercise has recently been undertaken to address
uncertainties with the detection and management of milk allergy in
children under two years of age.[12] Modifications to the Delphi
process are not an isolated practice in the health sciences[13] and
were necessary for the sake of brevity.[14] The online format
allowed the panel to be drawn from across the UK, so findings could
reflect practice variations which may exist between regions and
populations being served, and support the panel member commitment to the
whole process. The short timescale over which the consensus exercise was
conducted may have helped recall of previous rounds and maintained
engagement.
Nevertheless, the findings will not apply to all young children with AD
and opinions outside of the 14 panel members and the UK may be more
varied. It is also possible that had all panellists been able to engage
with all stages, the findings may been different. Although participants
were proficient at contributing and exchanging views online, persuasive
arguments may have been made or received differently in a face-to-face
meeting. Skin prick tests for milk and egg are more reliable than wheat
or soya and these results do not directly correlate with specific IgE
levels from blood tests. Although decision-making about food allergy
testing and subsequent dietary modifications should be shared and
discussed with parents and carers in a clinical consultation, because of
its technical nature patients representatives were not involved in this
process. However, the findings do begin to address the research
priorities identified by patients, carers and clinicians of “What role
might food allergy tests play in treating eczema?” and “What is the
role of diet in treating eczema: exclusion diets and nutritional
supplements?”[15]
The complexity of food allergy in children is such that it can be argued
that decision-making cannot be protocolised.[16] Allergy history
taking takes time, expertise and can be a subtle art, where through
careful conversation, concerns or symptoms can be identified as relevant
or reassurance given. This is particularly the case with severe AD of
early onset, certain symptom complexes (e.g. co-occurrence of skin and
gut symptoms), when multiple foods are implicated and/or there is a
prior food allergy diagnosis. Similarly, evidence of impact on the
growth and/or micronutrient deficiency trajectory of a child are
important considerations.[17] Although treatment plans can be
decided and advised with multidisciplinary support, their implementation
and maintenance relies on parents/carers understanding and ability to
adhere to them for the long-term. In the absence of any benefits
outweighing potential harms from routine food allergy to guide dietary
advice for the management of AD,[8] parents should still be
supported to use topical therapies to treat their child’s skin.
In consensus exercises, the context in which questions are presented is
important.[14] The same questions presented in another setting may
have elicited different responses. The context for this exercise, where
skin prick tests are performed on “all-comers”, departs from usual
clinical practice where symptoms are usually assessed first to determine
the merit of food allergy tests. It also assumes that for any child who
needs it, oral food challenges will be done in a timely manner,
something which currently does not happen in the UK, for example.
Finally, it also supposes that parents and carers of trial children will
be supported to safely exclude or reintroduction of study food(s) as
appropriate.
Findings in the context of the
literature
Dietary modification by parents of children with AD, seeking to reduce
symptoms, is common and often without any healthcare input.[6]
Undiagnosed delayed food allergy as the cause for AD symptoms and the
use of blood specific IgE or skin prick food allergy tests to guide
dietary advice is controversial. Clinical opinions are divided with
healthcare professionals but those working in allergy and paediatrics
are more likely to request a food allergy test than those working in
dermatology or primary care.[7, 18] Mortz et al have published an
algorithm (based on “expert opinion and available literature”) on
“When and how to evaluate for immediate (IgE‐mediated) food allergy in
children with atopic dermatitis”.[19] This similarly recommends
that a careful dietary history and an assessment of AD severity is
obtained prior to any allergen testing. Consequently, decision making
for children with no symptoms, immediate symptoms and/or moderate-severe
AD is relatively straightforward. On-going research, based on our
findings, will help to address the gap where there are parental concerns
in a child with mild AD and/or possible delayed symptoms.[20]
A recent systematic review of 10 RCTs concluded that dietary elimination
“may lead to a slight, potentially unimportant improvement in AD
severity, pruritus, and sleeplessness” in patients with mild to
moderate AD.[8] However, only four of the included studies had
interventions based on positive allergy tests, oral food challenges, or
both.[21-24] There was limited data on potential harms from such
interventions and as the authors point out, any potential benefits must
be balanced against the psychosocial impact of food exclusion,
developmental and nutritional problems and indeed the risk of developing
IgE-mediated food allergy.[25]
Implications for research, policymakers or
clinicians
Until further research clarifies the relationship between food allergy
and AD, and the role of food allergy tests, use of IgE food allergy
tests in clinical settings should continue be confined to help confirm
or refute the diagnosis of immediate-type allergies, following an
allergy focused history.[18] Clinicians need to be mindful that
parental concerns about food allergy and modifications to the diets of
children with AD is under-recognised and a dissonance can exist between
parental and clinicians views.[26] Regardless of opinions about food
allergy testing, clinicians should seek to identify and address these
issues as they can be a barrier to effective use of topical treatments
and have consequences for nutrition and diet quality.
Although food allergy testing may be sought by parents of children with
AD to guide dietary exclusions, the findings from this exercise can also
guide introduction, reintroduction and inclusion of foods where parents
are unsure based on symptoms, or have misplaced concerns which are
addressed by a negative skin prick test result.