Assesing the Probabiltiy of a Diagnosis of Asthma

Assessing the probablity of a diagnosis of asthma

Based on the initial clinical assessment it should be possible to determine the probability

of a diagnosis of asthma.

With a thorough history and examination, an individual child can usually be classed

into one of three groups

• high probability – diagnosis of asthma likely
• low probability – diagnosis other than asthma likely
• intermediate probability – diagnosis uncertain.

High probability of asthma

In children with a high probability of asthma based on the initial assessment, move

straight to a diagnostic trial of treatment. The initial choice of treatment will be based

on an assessment of the degree of asthma severity .The clinical response to treatment should be reassessed within 2–3 months. In this

group, reserve more detailed investigations for those whose response to treatment is

poor or those with severe disease

In children with a high probability of asthma:

start a trial of treatment

review and assess the response

reserve further testing for those with a poor response.

low probability of asthma

Where symptoms, signs or initial investigations suggest that a diagnosis of asthma is

unlikely or they point to an alternative diagnosis consider

further investigations. This may require referral for specialist assessment

Reconsider a diagnosis of asthma in those who do not respond to specific treatments.

In children with a low probability of asthma, consider more detailed investigation

and specialist referral.

Intermediate probability of asthma

In some children, and particularly those below the age of four to five, there is insufficient

evidence at the first consultation to make a firm diagnosis of asthma, but no features

to suggest an alternative diagnosis. There are several possible approaches to reaching

a diagnosis in this group. Which approach is taken will be influenced by the frequency

and severity of the symptoms. These approaches include:

Watchful waiting with review

In children with mild, intermittent wheeze and other respiratory symptoms which

occur only with viral upper respiratory infections (colds), it is often reasonable to give

no specific treatment and to plan a review of the child after an interval agreed with the

parents/carers.

Trial of treatment with review

The choice of treatment (for example, inhaled bronchodilators or corticosteroids)

depends on the severity and frequency of symptoms. Although a trial of therapy with

inhaled or oral corticosteroids is widely used to help make a diagnosis of asthma, there

is little objective evidence to support this approach in children with recurrent wheeze.

It can be difficult to assess the response to treatment, as an improvement in symptoms

or lung function may be due to spontaneous remission. If it is unclear whether a child

has improved, careful observation during a trial of withdrawing the treatment may

clarify whether a response to asthma therapy has occurred.

Diagnosis in children

Asthma in children causes recurrent respiratory symptoms of:

• wheezing
• cough
• difficulty breathing
• chest tightness.

Wheezing is one of a number of respiratory noises that occur in children. Parents often use

wheezing as a non-specific label to describe any abnormal respiratory noise. It is important

to distinguish wheezing – a continuous, high-pitched musical sound coming from the

chest – from other respiratory noises, such as stridor or rattly breathing.

There are many different causes of wheeze in childhood and different clinical patterns

of wheezing can be recognised in children. In general, these patterns (phenotypes) have

been assigned retrospectively. They cannot reliably be distinguished when an individual

child first presents with wheezing. In an individual child the pattern of symptoms may

change as they grow older.

The commonest clinical pattern, especially in pre-school children and infants, is episodes of

wheezing, cough and difficulty breathing associated with viral upper respiratory infections

(colds), with no persisting symptoms. Most of these children will stop having recurrent

chest symptoms by school age

Initial clinical assessment

The diagnosis of asthma in children is based on recognising a characteristic pattern of

episodic respiratory symptoms and signs (see Table 1) in the absence of an alternative

explanation for them .
Clinical features that increase the probability of asthma

More than one of the following symptoms: wheeze, cough, difficulty breathing,

chest tightness, particularly if these symptoms:

- are frequent and recurrent

- are worse at night and in the early morning

- occur in response to, or are worse after, exercise or other triggers, such as

exposure to pets, cold or damp air, or with emotions or laughter

- occur apart from colds

Personal history of atopic disorder

Family history of atopic disorder and/or asthma

Widespread wheeze heard on auscultation

History of improvement in symptoms or lung function in response to adequate

therapy

Clinical features that lower the probability of asthma

Symptoms with colds only, with no interval symptoms

Isolated cough in the absence of wheeze or difficulty breathing

History of moist cough

Prominent dizziness, light-headedness, peripheral tingling

Repeatedly normal physical examination of chest when symptomatic

Normal peak expiratory flow (PEF) or spirometry when symptomatic

 No response to a trial of asthma therapy

Clinical features pointing to alternative diagnosis

Several factors are associated with a high (or low) risk of developing persisting wheezing or asthma through childhood. The presence of these factors increases the probability that a child with respiratory symptoms will have asthma.