For a patient presenting with a chronic cough lasting more than eight weeks, initial investigations in General Practice should consider:
- Chest X-ray: This should be offered urgently (within 2 weeks) for unexplained cough in patients aged 40 and over who have ever smoked or been exposed to asbestos NICE NG12. It should also be considered urgently for persistent or recurrent chest infections in patients aged 40 and over NICE NG12.
- Spirometry: This is crucial for diagnosing Chronic Obstructive Pulmonary Disease (COPD), especially in people over 35 with a history of smoking or other risk factors NICE NG115. Post-bronchodilator spirometry is used to confirm a COPD diagnosis NICE NG115.
- Serial home peak flow measurements: These can be used to help exclude asthma if there is diagnostic uncertainty NICE NG115.
Additionally, an important initial consideration is to assess for an Angiotensin-converting enzyme (ACE) inhibitor-induced cough. If suspected, stopping the ACE inhibitor treatment and prescribing an alternative is an initial management step, with the cough typically resolving within one month NICE CKS.
If the cough does not respond to initial therapeutic trials, or the diagnosis remains uncertain, referral to a respiratory physician for specialist assessment and further investigations (such as methacholine challenge, sputum cytology, or immunologic tests) may be necessary NICE CKS. In palliative care, investigations like a chest X-ray may be considered if a pleural effusion is suspected, with more advanced imaging (CT/MRI) or bronchoscopy potentially carried out in secondary care NICE CKS.