C2. Diagnosis

C2.1 History

The main symptoms of COPD are breathlessness, cough and sputum production.²³ Patients often attribute breathlessness to ageing or lack of fitness. A persistent cough, typically worse in the mornings with mucoid sputum, is common in smokers. Other symptoms such as chest tightness, wheezing and airway irritability are common.²⁴ Acute exacerbations, usually infective, occur from time to time and may lead to a sharp deterioration in coping ability. Fatigue, poor appetite and weight loss are more common in advanced disease.

The functional limitation from breathlessness due to COPD can be quantified easily in clinical practice²⁵ (see Box 4).

C2.2 Physical examination

The sensitivity of physical examination for detecting mild to moderate COPD is poor.²⁶ Wheezing is not an indicator of severity of disease and is often absent in stable, severe COPD. In more advanced disease, physical features commonly found are hyperinflation of the chest, reduced chest expansion, hyperresonance to percussion, soft breath sounds and a prolonged expiratory phase. Right heart failure may complicate severe disease.

During an acute exacerbation, tachypnoea, tachycardia, use of accessory muscles, tracheal tug and cyanosis are common.

The presence and severity of airflow limitation are impossible to determine by clinical signs.²⁶ Objective measurements such as spirometry are essential. Peak expiratory flow (PEF) is not a sensitive measure of airway function in COPD patients, as it is effort dependent and has a wide range of normal values.²⁷

C2.3 Spirometry

Because COPD is defined by a post-bronchodilator FEV₁/FVC ratio < 0.7, spirometry is essential for its diagnosis (see Box 5). Most spirometers provide predicted ("normal") values obtained from healthy population studies, and derived from formulas based on height, age, sex and ethnicity.

Airflow limitation is not fully reversible when, after administration of bronchodilator medication, the ratio of FEV₁ to forced vital capacity (FVC) is < 70% and the FEV₁ is < 80% of the predicted value. The ratio of FEV₁ to vital capacity (VC) is a sensitive indicator for mild COPD.

A detailed systematic review states that spirometry, in addition to clinical examination, improves the diagnostic accuracy of COPD compared to clinical examination alone reinforcing the imprtance of spirometry²⁹ [evidence level I]. More studies are required to define any benefit from the use of spirometry for case finding in COPD, and to evaluate the effects of spirometric results on smoking cessation. The spirometric tests require high levels of patient effort and cooperation, and there are important quality criteria that should be met in conducting spirometry.³⁰

Indications for spirometry include:

• breathlessness that seems inappropriate;

• chronic (daily for two months) or intermittent, unusual cough;

• frequent or unusual sputum production;

• relapsing acute infective bronchitis; and

• risk factors such as exposure to tobacco smoke, occupational dusts and chemicals, and a strong family history of COPD.

C2.4 Flow volume tests

Electronic spirometers allow for the simultaneous measurement of flow and volume during maximal expiration. Reduced expiratory flows at mid and low lung volumes are the earliest indicators of airflow limitation in COPD and may be abnormal even when FEV₁ is within the normal range (> 80%).