Check Programme
The Hong Kong Practitioner VOLUME 27 / December 2006

Case one: Peter, aged 20 years, is a university student studying computer sciences. He considers himself a 'nerd' and seldom makes time for physical activities and sport. Although Peter has always been healthy, over the past 6 weeks an irritating cough has started to bother him, followed by a few days in bed with the 'flu'. The cough has persisted and is the reason for coming to see you. He does not smoke but admits to smoking 1-2 cigarettes at a party on rare occasions. Two course of antibiotics have not helped.
 
 
Question 1: What are the important question to ask Peter?
 
 
 
 
 
 
Question 2: Peter reports that it is a dry cough that occasionally wakes him up at night. There is no wheezing or breathlessness with exercise. He gets seasonal hay fever and his mother has asthma. He has not experienced fever with this illness but says he may have lost some weight. What is your next step?
 
 
 
 
 
 
Question 3: The results are normal with no evidence of infection. You discuss with Peter that he may have asthma but he wants to be sure before taking any treatments. How can the diagnosis be vertified?
 
 
 
 
 
 
Question 4: What is a methacholine provocation test and how are the results interpreted\?
 
 
 
 
 
 
Question 5: Peter's results are shown in Figure 2. What will you tell him?
 
 
 
 
Figure 2. Peter's methacholine provocation test result
 
 
Question 6: Given the fact that Peter does not notice wheeze, is this asthma or transient airway hyper-responsiveness?
 
 
 
 
 
 
Question 7: Are any treatment indicated?
 
 
 
 
 
 
Question 8: How long should treatment be continued?
 
 
 
 
 
 


Answer 1

Ask Peter about sputum production, fevers, weight loss and exposure to tuberculosis in relation to infections. Questions about breathlessness, wheezing, night cough and wheezing, hay fever and a family history of allergy or asthma will provide valuable information.

Answer 2

Chest X-ray is important. Peter has had a previous acute illness, may have lost weight and could have been exposed to tuberculosis at university.

It is possible that Peter has asthma with cough as the predominant symptom ('cough variant asthma'). Consideration must be given to verifying the diagnosis or starting asthma medication to judge the clinical response.

Answer 3

Bronchial hyper-responsiveness (BHR) can be produced in the laboratory by a number of tests. This is not necessarily the same as a diagnosis of asthma. Nonasthmatic people can exhibit BHR in response to certain stimuli. Despite a positive challenge, the diagnosis of asthma must be grounded in a history and examination consistent with the diagnosis. However, a positive exercise challenge indicates exercise induced asthma. In young people, exercise is often a potent inducer but usually methacholine bronchoprovocation is easiest. Other methods include hypertonic saline and mannitol bronchoprovocation. The latter has considerable potential and may eventually become the test of first choice because of its potential simplicity with high diagnostic sensitivity and specificity.

Answer 4

Methacholine provocation can be used to confirm asthma in a patient with suggestive clinical features. During methacholine provocation increasing concentrations of the compound are inhaled followed by measurements of forced expiratory volume - 1 second (FEV1). If FEV1 decreases by >20% a diagnosis of airway hyper-responsiveness and by implication asthma can be made.

Answer 5

Peter's result shows a reduction of more than 20% in FEV1 in response to methacholine provocation and you tell him he has a clearly positive test.

Answer 6

That is a difficult and unresolved question. People with underlying asthma/allergy have airway hyper-responsiveness often worsened (and made clinically detectable) by viral infections. However, viruses can also induce hyper-responsiveness independent of allergy and asthma - and cough is often the dominant symptom.

Answer 7

Given the positive provocation test treatment with an anti-inflammatory agent (eg. inhaled corticosteroids) is merited. However, in people without evidence of asthma, the use of such treatments has not been proven and should not be used. Even in cases where the diagnosis is established, back titration of the inhaled corticosteroid dose to the lowest possible to control symptoms is important.

Answer 8

There are no clear guidelines in this context. The difficulty lies in the fact that the natural history is unknown, so an apparent improvement on treatment might simply be the natural healing of the condition. However, given that airway inflammation is likely to be the fundamental abnormality causing symptoms, it is probably wise to use anti-inflammatory medications for no shorter than 3-6 months after symptoms have resolved. If symptoms do not resolve despite treatment, the diagnosis needs to be reconsidered. More research and evidence are needed to clarify diagnostic issues and best treatment practices in 'cough variant asthma'.

Case feedback

Peter's cough improved gradually on regular daily inhaled corticosteroids, and at 3 month review he became asymptomatic.
 
 
Royal Australian College of General Practitioners