Persistent cough – diagnosis and management

What is a persistent cough?

Persistent cough is, by definition, a cough which lasts for 8 weeks or longer. This will usually be a dry cough as most coughs which produce sputum are relatively easy to diagnose. Persistent coughs, however, may elude diagnosis for a long time until a specialist chest physician becomes involved.

This is because routinely-available investigations such as chest x-rays and CT scans can show no abnormality and, in the absence of special expertise, the causes often remain hidden. Since the conditions which cause these coughs do not represent life-threatening illnesses, both patients and their doctors sometimes just accept the cough as a fact of life and the patient goes on suffering indefinitely.

However, continual coughs may contribute to other problems like anxiety, depression, chest pains, sleeplessness, stress incontinence, or difficulty attending public events.

How are persistent coughs diagnosed?

Many persistent cough patients have conditions which are actually simple to diagnose if the doctor asks the right questions. New, research-validated questionnaires are vital in ensuring this. For example, they can help decide whether the cough originates in the throat or the chest, a very important distinction. Other questionnaires might determine whether the cough is related to oesophageal reflux, for example, a common but under-diagnosed cause.

When a patient visits our clinic, the first priority is to rule out a serious cause for coughing such as lung cancer or diseases of the lung structure. This requires a careful history, examination and investigation such as chest x-rays and CT scans. Once this is established, we move on to considering the more common causes. It is also important to establish whether there might be more than one cause.

Many cases can be diagnosed on history alone. In these circumstances, a trial of appropriate treatment is undertaken and a positive outcome confirms the diagnosis.

In cases of doubt, confirmatory tests are advised. Possible tests that may be requested include:

• Computerised tomography: cross-sectional X-ray imaging of the thorax (chest) and upper abdomen
• Lung function: measurements of airflow are made by breathing in and out of specially-calibrated equipment to determine the presence or absence of airflow obstruction
• Bronchial provocation: a test for irritability of the airways to establish the presence of mild asthma where lung function remains within the normal range
• pH and manometry: this records acidity of the oesophagus over 24 hours to detect fluid reflux

What happens if there is still no diagnosis?

If a patient is still unable to be diagnosed, they will be considered to be suffering from Chronic Refractory Cough. Fortunately, there is now understanding of the likely origin of this type of cough, which can be treated with a number of possible drugs, speech and language therapy, and sometimes a combination of both.

We manage to provide relief for many patients. During the process, the chest physician may be assisted by ear, nose and throat (ENT) specialists, or various gastrointestinal specialists. Some patients do elude diagnosis but most are helped through consultation with specialists and the testing offered.

To make an appointment with our Consultant Chest Physician click here, or phone us on 0207 079 2102.