A 26 Year Old Woman presents To Her General Physician With Persistent Cough

A 26-year-old teacher has consulted her general practitioner (GP) for her persistent cough. She wants to have a second course of antibiotics because an initial course of amoxicillin made no difference. The cough has troubled her for 3 months, since she moved to a new school. The cough is now disturbing her sleep and making her tired during the day. She teaches games, and the cough is troublesome when going out to the playground and when jogging.
In her medical history she had her appendix removed 3 years ago. She had her tonsils removed as a child and was said to have recurrent episodes of bronchitis between the ages of 3 and 6 years.
She has never smoked and takes no medication other than an oral contraceptive. Her parents are alive, and well and she has two brothers, one of whom has hay fever.

On Examination
The respiratory rate is 18/min. Her chest is clear, and there are no abnormalities in the nose or pharynx or the cardiovascular, respiratory or nervous systems.

Investigations:
• Chest X-ray is reported as normal.
• Spirometry is carried out at the clinic, and she is asked to record her peak flow rate at home, the best of three readings every morning and every evening for 2 weeks. Spirometry results are as follows:
FEV1 (L) = 3.9   ( predicted = 3.6–4.2)
FVC (L) = 5.0     ( predicted =  4.5–5.4)
FER (FEV1/FVC) (%) = 78   ( predicted = 75–80)
PEF (L/min)  =  470   ( predicted = 440–540)

Peak flow recording at home showed diurnal variations.

Questions
• What is your interpretation of these findings?
• What do you think is the likely diagnosis, and what would be appropriate treatment?

Answers and Case Discussion:

The peak flow pattern shows a degree of diurnal variation. This does not reach the diagnostic criteria for asthma, but it is suspicious. The mean daily variation in peak flow from the recordings is 36 L/min, and the mean evening peak flow is 453 L/min, giving a mean diurnal variation of 8 per cent. There is a small diurnal variation in normals, and a variation of >15 per cent is diagnostic of asthma. In this patient the label of ‘bronchitis’ as a child was probably asthma. The family history of an atopic condition (hay fever in a brother) and the triggering of the cough by exercise and going out in the cold also suggest bronchial hyperresponsiveness typical of asthma.
Patients with a chronic persistent cough of unexplained cause should have a chest X-ray. When the X-ray is clear the cough is likely to be produced by one of three main causes in non-smokers. Around half of such cases have asthma or will go on to develop asthma over the next few years. Half of the rest have rhinitis or sinusitis with a postnasal drip. In around 20 per cent the cough is related to gastro-oesophageal reflux. A small number of cases will be caused by otherwise-unsuspected problems such as foreign bodies, bronchial ‘adenoma’, sarcoidosis or fibrosing alveolitis. Cough is a common side effect in patients treated with angiotensin-converting enzyme (ACE) inhibitors.

In this patient the diagnosis of asthma was confirmed with an exercise test, which was associated with a 25 per cent drop in FEV after completion of 6 min of vigorous exercise. Alternative bronchoprovocation tests include the use of inhaled methacholine or histamine, and a fall in FEV1 greater than 20 per cent.
After the exercise test, an inhaled steroid was given, and the cough settled after 1 week. The inhaled steroid was discontinued after 4 weeks and replaced by a β2-agonist to use before exercise. However, the cough recurred with more evident wheeze and shortness of breath, and treatment was changed back to an inhaled steroid with a β2-agonist as needed. If control was not established, the next step would be to check inhaler technique and treatment adherence and to consider adding a long-acting β2-agonist. In some cases, the persistent dry cough associated with asthma may require more vigorous treatment than this. Inhaled steroids for a month or more or even a 2-week course of oral steroids may be needed to relieve the cough.
The successful management of dry cough relies on establishing the correct diagnosis and treating it vigorously.

Key Points:
• The three commonest causes of persistent dry cough with a normal chest X-ray are

1. asthma (50 per cent), 
2. sinusitis & postnasal drip (25 per cent) and 
3. reflux oesophagitis (20 per cent).

• Asthma may present as a cough (cough-variant asthma) with little or no airflow obstruction initially, although this develops later.
• Persistent cough with normal chest examination is unlikely to have a bacterial cause or respond to antibiotic treatment.