Chronic obstructive pulmonary disease (COPD) is a preventable and treatable disease characterised by airflow obstructions which is usually progressive, not fully reversible and does not change markedly over several months (1,2).

• a combination of airway and parenchymal damage caused by chronic inflammation due  to tobacco smoke and other noxious particles or gases is responsible for the airflow obstruction
• the definition of airflow obstruction include - a reduced post bronchodilator FEV1/FVC ratio (where FEV1 is forced expiratory volume in 1 second and FVC is forced vital capacity) such that FEV1/FVC is less than 0.7
• if FEV1 is ≥ 80% predicted normal diagnosis of COPD should only be made in the presence of respiratory symptoms e.g. - breathlessness or cough

COPD is now the preferred term which covers many previously used clinical labels which are now recognised as being different aspects of the same problem. Diagnostic labels encompassed by COPD include:

• chronic bronchitis
• emphysema
• chronic obstructive airways disease
• chronic airflow limitation
• some cases of chronic asthma.

COPD is an important cause of activity limitation in the population.

Environmental pollution and smoking contribute to the increasing incidence of COPD.

• Assessment and classification of severity of airflow obstruction

  The severity of airflow obstruction should be assessed according to the reduction in FEV1 as shown in table

  Post-bronchodilator FEV1/FVC	FEV1 % predicted	Severity of airflow obstruction Using NICE clinical guideline 12 (2004)	Severity of airflow obstruction Using ATS/ERS 2004	Severity of airflow obstruction Using GOLD 2008	Severity of airflow obstruction Using NICE clinical guideline 101 (2010)
  			Post-bronchodilator	Post-bronchodilator	Post-bronchodilator
  < 0.7	>80%		Mild	Stage 1 - Mild Stage	Stage 1 - Mild*
  < 0.7	50-79%	Mild	Moderate	Stage 2 - Moderate	Stage 2 - Moderate
  < 0.7	30-49%	Moderate	Severe	Stage 3 - Severe	Stage 3 - Severe
  < 0.7	< 30%	Severe	Very severe	Stage 4 - Very severe**	Stage 4 - Very severe **

  *Symptoms should be present to diagnose COPD in people with mild airflow obstruction

  **Or FEV1 < 50% with respiratory failure.

  Celli BR, MacNee W (2004) Standards for the diagnosis and treatment of patients with COPD: a summary of the ATS/ERS position paper. European Respiratory Journal 23(6): 932-46.

Global Initiative for Chronic Obstructive Lung Disease (GOLD) (2008) Global strategy for the diagnosis, management, and prevention of chronic obstructive pulmonary disease

Reference:

• (1) Viegi G et al. Definition, epidemiology and natural history of COPD. Eur Respir J. 2007;30(5):993-1013.
• (2) National Institute for Health and Clinical Excellence (NICE) 2010. Chronic obstructive pulmonary disease: Management of chronic obstructive pulmonary disease in adults in primary and secondary care.