The Global Initiative of Chronic Obstructive Lung Disease (GOLD) – a project initiated by the US National Heart, Lung, and Blood institute (NHLBI) and the World Health Organisation defines COPD as follows:
'Chronic obstructive pulmonary disease (COPD), a common preventable and treatable disease, is characterized by airflow limitation that is usually progressive and associated with an enhanced chronic inflammatory response in the airways and the lung to noxious particles or gases. Exacerbations and comorbidities contribute to the overall severity in individual patients.'
COPD may be caused by chronic bronchitis, chronic asthma, emphysema, and alpha-1 antitrypsin deficiency. The most important risk factor for COPD is smoking. Around 80% of people affected by COPD have a history of smoking. In the absence of genetic / environmental predispositions, smoking less than 10 pack years is unlikely to result in COPD while smoking more than 40 pack years has a positive likelihood ratio of 12 [Confidence interval 2.7-50]. Thus inquiring about smoking habits is important.
Symptoms of COPD include chronic chough, sputum production and dyspnoea. Exertional dyspnoea is an early symptom.
Pulmonary functions tests are the cornerstone in the diagnosis of COPD. The most important values measured during spirometry are the forced expiratory volume in one second (FEV1) and the forced vital capacity (FVC). The post bronchodilator ratio FEV1/FVC determines the severity of irreversible airflow limitation. A ratio of less than 0.7 is considered abnormal however the normal value decreases with age. The force expiratory volume in six seconds (FEV6) obtained by stopping expiratory effort a 6 seconds is an acceptable surrogate for FVC. Spirometry reference values are available from:
Please refer also to the Asthma section for spirometry normal values.
The Revised GOLD Classification looks at three things: Symptoms (Dyspnoea), FEV1 and history of Exacerbations.
|Grade 0:||'I only get breathless with strenuous exercise.'|
|Grade 1:||'I get short of breath when hurrying on level ground or walking up a slight hill.'|
|Grade 2:||'On level ground, I walk slower than people of the same age because of breathlessness, of have to stop for breath when walking at my own pace.'|
|Grade 3:||'I stop for breath after walking about 100 meters or after a few minutes on level ground.'|
|Grade 4:||'I am too breathless to leave the house or I am breathless when dressing.'|
|GOLD 1||Mild||FEV1>80% of predicted (but has other positive markers)|
|GOLD 2||Moderate||50% <FEV1<80%|
|GOLD 3||Severe||30% <FEV1<50%|
|GOLD 4||Very severe||FEV1 <30%|
|Low risk:||1 or less exacerbations per year|
|High risk:||2 or more exacerbations per year|