Asthma and COPD are both characterised by pulmonary airways obstruction. Asthma is defined as reversible airways obstruction and COPD as largely irreversible obstruction due to a combination of bronchial mucosal inflammation and destruction of supportive elastic tissue (emphysema), both a result of cigarette smoking. More recently, asthma has been characterised as a predominantly inflammatory disease, with bronchial inflammation contributing to airways obstruction, both directly through mucosal thickening and indirectly through bronchial smooth muscle contraction and spasm.

A diagnosis of asthma is favoured when the symptoms are intermittent and reversible, the age of onset younger and when the patient is a non-smoker. There may also be a personal and/or family history of atopy or allergy. A diagnosis of COPD is favoured when the patient is older, a smoker and has little or no demonstrable reversibility of airways obstruction. However, many patients have features that favour neither one nor the other. A proportion of asthmatics are smokers and unfortunately smoking cessation rarely results in short term improvement in symptoms. Asthma may also present late in life and in these cases response to treatment may be less convincing than in the younger atopic patient.

Until recently the need to make the distinction between asthma and COPD was not critical since the treatment was largely identical – beta-agonists, anti-muscarinic agents and inhaled steroids were recommended for both. Recently, however, two sets of guidelines have been published that clearly distinguish between the recommended therapeutic approach for each of the conditions.

The British Thoracic Society (BTS) revised its guidelines on the management of asthma in 2014¹ and the National Institute for Health and Care Excellence (NICE) currently has a draft of its revised clinical guideline out for consultation.² Inhaled corticosteroids are now strongly favoured as first-line treatment, with short-acting beta-agonists reserved for relief of breathlessness or wheeze. For those who continue to require regular beta-agonists a combination long-acting beta-agonist (LABA) and inhaled corticosteroid is recommended. Anti-muscarinics, prostaglandin antagonists and theophylline are used as third-line treatment.

The Global Initiative for Chronic Obstructive Lung Disease (GOLD) has similarly reviewed the recommendations for COPD.² Anti-muscarinic (anti-cholinergic) drugs are now recommended as first-line treatment for COPD, with long-acting anti-muscarinic and beta-agonist (LAMA/LABA) combinations as an alternative for moderate-to-severe cases. The evidence for use of inhaled corticosteroids in COPD is less convincing. In addition, GOLD published specific recommendations on asthma, COPD and asthma-COPD overlap syndrome (ACOS) last year and these have been appended to the latest GOLD COPD guidelines published in January 2015.²

These guidelines now clearly distinguish first-line management strategies for asthma and COPD, with inhaled corticosteroids for the former and anti-muscarinics for the latter. It is therefore important to look for reversibility and atopy, which may favour asthma, and for radiological emphysema and irreversible airways obstruction, which may favour COPD, and to select initial therapy accordingly.

References

1. British Thoracic Society. Scottish Intercollegiate Guidelines Network. British guideline on the management of asthma. A national clinical guideline. October 2014. www.brit-thoracic.org.uk/document-library/clinical-information/asthma/btssign-asthma-guideline-2014
2. National Institute for Health and Care Excellence. Asthma: diagnosis and monitoring of asthma in adults, children and young people. Clinical guideline. Methods, evidence and recommendations, Jan 2015. www.nice.org.uk/guidance/gid-cgwave0640/resources/asthma-diagnosis-and-monitoring-draft-guideline2
3. Global Strategy for the Diagnosis, Management and Prevention of COPD, Global Initiative for Chronic Obstructive Lung Disease (GOLD) 2015. Available from www.goldcopd.org