Is it Difficult to Treat Asthma in Children?

Asthma, the commonest chronic lung disease in childhood, is managed effectively with inhaled medications in most of the cases. But a subset of pediatric asthma patients continues to experience substantial morbidity even after higher doses of medications; they are referred to as problematic severe asthma. In many such cases, the apparent resistance to therapy is actually due to a number of remediable factors. These cases are called ‘difficult to treat asthma’. The physician dealing with a child with problematic severe asthma needs to follow a systematic step- wise approach to find any possible underlying causes of poor response to therapy. The evaluation starts with revisiting the diagnosis of asthma and goes through a checking the prescription, patient compliance, assessment for co-morbidities, environmental triggers and psychological factors. Only in a very small number of cases where no such remediable factors are identified, a diagnosis of severe therapy-resistant asthma is made and the child should be referred to a pediatric pulmonologist for further evaluation and therapy.


Introduction
Childhood asthma is the most common chronic lung disease of childhood and is one of the greatest burdens on healthcare resources [1].
Though the disease can be controlled adequately with inhaled corticosteroids and ß2 agonists in most cases, a subset of patients (about 0.5-5%) continues to experience significant morbidity despite therapy [2]. Difficult to treat asthma (DTA) is significant ongoing symptoms due to underlying modifiable factors, which when addressed leads to better control, and not due to resistance to medications [3]. It comprises of only 5-10% of all asthmatics but accounts for approximately 50% of total cost of asthma therapy [4]. Up to 40 % of children referred for investigation of 'severe asthma' fall in this group [5].

Nomenclature
A variety of terminologies has been used to describe children with severe asthma [6] such as refractory asthma, difficult to control asthma, brittle asthma, chronic severe asthma, therapyresistant asthma, steroid-dependent asthma.
Although these may sound confusing, actually each one of these names points to a different aspect of the condition. According to the currently accepted nomenclature, problematic severe asthma is defined as asthma that is poorly controlled despite high doses of prescribed

Pre-school children
Any child falling into one or more of the following categories despite trials of maximal guidelinerecommended treatment:  Need for alternate-day or daily oral steroids to achieve control Once a child with asthma fits into the above definition, the next responsibility of the physician is to follow a systematic approach to find a remediable cause of the presumed 'non-response' in the child. If such a factor is found then the child is labeled as 'difficult to treat asthma' and those factors are addressed but in the case of inability to find any such factors, a diagnosis of 'severe therapy-resistant asthma' is made.
Approach to "Difficult to Treat Asthma (DTA)" Step 1: Ascertain the diagnosis It has been aptly said that "all that wheezes is not asthma!" It was found that 50% of children investigated for problematic severe asthma found to have the incorrect diagnosis or to have an associated diagnosis [12]. Therefore, the first step is to ensure the child has asthma and not another wheezing disorder or disorder with noisy breathing.
Disorders that may be wrongly diagnosed as Symptoms such as productive cough points towards an alternate diagnosis of suppurative lung disease, while exercise-induced dyspnea along with stridor especially in an adolescent is strongly suggestive of vocal cord dysfunction.
There is no clinical examination finding which is confirmatory of asthma. A child having an acute exacerbation will be having a variable degree of respiratory distress with/ without hypoxemia and polyphonic wheeze.
A child with inadequate control on medications may or may not demonstrate wheeze at the time of examination but will develop symptoms on exertion. There are definitely certain 'red flags' which when present should make the physician think about a diagnosis other than asthma and also dictate appropriate investigations (Table 2  Step 2: Check prescription After a correct diagnosis of asthma is made, it is equally important to select the most appropriate plan of therapy for the patient. The choice of inhalation devices, the most commonly used medication delivery method in children with asthma, varies with the age and developmental abilities of the child (Table 3).

Step 4: Search for co-morbid conditions
Certain disorders that accompany and exacerbate asthma should be looked for in children with problematic severe asthma.