Introduction
The epidemiology of pre-school wheeze is covered in detail elsewhere in
this series. In brief, this is a common problem with few solutions. In
the UK, the greatest burden of hospitalisations for wheeze is on
children age less than 5 years old [1,2]. Most suffer from recurrent
episodic, commonly viral induced attacks (EVW). Most remit over time
[3]. Worldwide, preschool wheeze is a problem in all environments
[4], which makes it all the more disappointing that we have so few
evidence based, personalised treatments
The treatment of preschool wheeze, especially the role of inhaled
corticosteroids (ICS), has been be-devilled by the mindless “at what
age can asthma be diagnosed?”. Clearly the answer depends on the
definition of asthma [5]. The Lancet Asthma Commission cut
through this by defining asthma purely clinically, wheeze, chest
tightness, breathlessness and sometimes excessive cough [6]. This is
because asthma is considered an umbrella term like anaemia (low
haemoglobin) and arthritis (hot, painful joints). As with anaemia and
arthritis, so with asthma, the next question is, “what sort of asthma
has this child got?” with a specific focus on treatable traits [7]
(Table 1). Notably, the treatable trait approach should be extended
beyond pulmonary disease; description of the detailed management of
extrapulmonary and social/environmental treatable traits is outwith the
scope of this review. However consideration of these traits is necessary
for the holistic management of the child Thus, asthma can be diagnosed
at any age if a good history is taken, but the underlying endotype will
vary across the life course. In preschool wheeze, the key treatable
traits are the presence or otherwise of eosinophilic airway
inflammation, bronchodilator responsiveness, and bacterial airway
infection. Thus the management approach set out in this review draws on
this paradigm to determine treatment options. Preschool is defined as
age 2-5 years inclusive. Very little is known about the pathophysiology
and management of wheeze in the first year of life [8]. We do know
that there is no evidence of airway inflammation in these very young
children, even if they are really severely affected, atopic and with
documented acute bronchodilator reversibility [9]; it is thus very
difficult to justify any prescription of ICS in wheezing babies.