Chronic obstructive pulmonary disease (COPD) is characterised by airflow obstruction that is usually progressive, not fully reversible and does not change markedly over several months. The diagnosis is suspected on the basis of symptoms (particularly breathlessness or cough) and signs, and supported by spirometry.
- In the early stages, COPD may produce minimal or no symptoms.
- Opportunistic case finding should be based on the presence of risk factors (age and smoking) and symptoms. The diagnosis should be confirmed using spirometry.
- As the disease progresses, the symptoms in individual patients vary.
- Individual symptoms in isolation are not useful in excluding or making the diagnosis of COPD.
- A diagnosis of COPD should be considered in patients over the age of 35 who have a risk factor (generally smoking) and who present with one or more of the following symptoms:
- Exertional breathlessness
- Chronic cough
- Regular sputum production
- Frequent winter 'bronchitis'
- Patients in whom a diagnosis of COPD is considered should also be asked about the presence of the following factors: weight loss, effort intolerance, waking at night, ankle swelling, fatigue.
The Medical Research Council (MRC) dyspnoea scale should be used to grade the level of breathlessness:
- Not troubled by breathlessness except on strenuous exercise.
- Short of breath when hurrying or walking up a slight hill.
- Walks slower than contemporaries on level ground because of breathlessness or has to stop for breath when walking at own pace.
- Stops for breath after walking about 100 m or after a few minutes on level ground.
- Too breathless to leave the house, or breathless when dressing or undressing.
Individual clinical signs are not helpful in making a diagnosis of COPD and in some patients there may be no abnormal physical signs. The following signs may be present:
- Hyperinflated chest, pursed lip breathing, use of accessory muscles, paradoxical movement of lower ribs, reduced cricosternal distance.
- Wheeze or quiet breath sounds.
- Reduced cardiac dullness on percussion.
- Peripheral oedema.
- Raised jugular venous pressure (JVP).
- Congestive cardiac failure
- Lung cancer
- Obliterative bronchiolitis
- Bronchopulmonary dysplasia
- Spirometry should be performed in patients who are aged over 35, are current or ex-smokers, and who have a chronic cough.
- Spirometry should be considered in patients with chronic bronchitis. A significant proportion of these will go on to develop airflow limitation.
- A true assessment of severity should include assessment of the degree of airflow obstruction and disability, the frequency of exacerbations and the following prognostic factors:
- Health status, breathlessness (MRC scale), body mass index (BMI), exercise capacity.
- Forced expiratory volume in one second (FEV1), arterial blood gases for partial pressure of oxygen in arterial blood (PaO2).
- Presence of complications - eg, cor pulmonale.
The BODE index (= BMI, airflow Obstruction, Dyspnoea and Exercise capacity index) should be used to assess the prognosis when the component information is available: measurement of the BODE index includes measurement of BMI, FEV1 as percentage of predicted, dyspnoea (modified MRC score) and exercise tolerance (six-minute walking distance).
Peak expiratory flow rate (PEFR)
- Measurement may significantly underestimate the severity of the airflow limitation.
- A normal PEFR does not exclude significant airflow obstruction.
See also the separate article Spirometry Calculator. Spirometry can be used to assess the severity of airflow obstruction and can be used to guide therapy and predict prognosis. However, using spirometry alone may underestimate the impact of the disease in some patients and overestimate it in others. Mild airflow obstruction can be associated with significant disability in patients with COPD.
- Spirometry is the only accurate method of measuring the airflow obstruction in patients with COPD. Spirometry should be performed at the time of diagnosis and to reconsider the diagnosis, if patients show an exceptionally good response to treatment.
- The recommended European Respiratory Society (ERS) 1993 reference values may lead to underdiagnosis in the elderly and are not applicable in black and Asian populations.
- A diagnosis of airflow obstruction can be made for FEV1/forced vital capacity (FVC) less than 0.7 (ie 70%) and FEV1 less than 80% predicted.
- Values for the FEV1 and FVC must be compared with the predicted normal values which depend on the individual's age, height and sex.
- National Institute for Health and Care Excellence (NICE) classification of the severity of COPD:
- Stage 1; Mild: FEV1 is > 80% predicted.
- Stage 2; Moderate: FEV1 is 50-79% predicted.
- Stage 3; Severe: FEV1 is 30-49% predicted.
- Stage 4: Very severe: FEV1 is below 30% predicted (or FEV1 less than 50% but with respiratory failure).
- Spirometry is a poor predictor of disability and quality of life in COPD but helps in predicting prognosis and contributes to the assessment of the severity of COPD. Spirometry alone cannot separate asthma from COPD.
- Reversibility testing:
- In most cases the diagnosis of COPD is suggested by the combination of the clinical history, signs and baseline spirometry. Reversibility testing does not add any additional information.
- There is now evidence that the clinical response to bronchodilators or inhaled corticosteroids cannot be predicted by response to a reversibility test. If patients report a marked improvement in symptoms in response to inhaled therapy, the diagnosis of COPD should be reconsidered.
- Longitudinal observation of patients (whether using spirometry, peak flow or symptoms) should also be used to help differentiate COPD from asthma. To help resolve cases where diagnostic doubt remains, or both COPD and asthma are present, the following findings should be used to help identify asthma:
- Large (over 400 ml) response to bronchodilators.
- Large (over 400 ml) response to 30 mg oral prednisolone daily for two weeks.
- Serial peak flow measurements showing 20% or greater diurnal or day-to-day variability.
- Clinically significant COPD is not present if the FEV1 and FEV1/FVC ratio return to normal with drug therapy.
- Changes in the flow volume loop may give additional information about mild airflow obstruction.
- Measurement of the slow vital capacity may allow the assessment of airflow obstruction in patients who are unable to perform a forced manoeuvre to full exhalation.
If diagnostic uncertainty remains, referral for more detailed investigations, including imaging and measurement of carbon monoxide transfer factor should be considered.
- At the time of their initial diagnostic evaluation, in addition to spirometry all patients should have:
- CXR to exclude other pathologies.
- FBC to identify anaemia or polycythaemia.
- BMI calculated.
- Additional investigations should be performed to aid management in some circumstances:
- Serial domiciliary peak flow measurements: to exclude asthma if diagnostic doubt remains.
- Alpha-1-antitrypsin: if early onset, minimal smoking history or family history.
- Measurement of carbon monoxide transfer factor: to investigate symptoms that seem disproportionate to the spirometric impairment.
- CT scan of the thorax: to investigate symptoms that seem disproportionate to the spirometric impairment, investigate abnormalities seen on a CXR and assess suitability for surgery.
- ECG: to assess cardiac status if there are features of cor pulmonale.
- Echocardiogram: to assess cardiac status if there are features of cor pulmonale.
- Pulse oximetry: to assess the need for oxygen therapy. If there is cyanosis or cor pulmonale present, or if FEV1 is less than 50% predicted.
- Sputum culture: to identify organisms if sputum is persistently present and purulent.
Further reading and references
; NICE CKS, November 2010 (UK access only)
; Diagnosis and management of stable chronic obstructive pulmonary disease: a clinical practice guideline update from the American College of Physicians, American College of Chest Physicians, American Thoracic Society, and European Respiratory Society. Ann Intern Med. 2011 Aug 2155(3):179-91. doi: 10.7326/0003-4819-155-3-201108020-00008.
; NICE Clinical Guideline (June 2010)
; Bronchodilator responsiveness as a phenotypic characteristic of established chronic obstructive pulmonary disease. Thorax. 2012 Aug67(8):701-8. doi: 10.1136/thoraxjnl-2011-201458. Epub 2012 Jun 13.
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