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Diagnosis and management of COPD in primary care

David Bellamy MBE
BSc FRCP MRCGP
GP
Bournemouth
E:david.bellamy@virgin.net

Chronic obstructive airways disease is the internationally accepted term for a spectrum of respiratory conditions, which include chronic bronchitis, emphysema and chronic persistent asthma that has become unresponsive to standard therapy. The recently published GOLD (Global Initiative for Chronic Obstructive Lung Disease) guidelines have succinctly defined COPD (chronic obstructive pulmonary disease) as "a disease state characterised by airflow limitation that is not fully reversible. The airflow limitation is usually both progressive and associated with an abnormal inflammatory response of the lungs to noxious particles and gases."(1)
The term COPD is not that well known by patients. A survey performed on behalf of the British Thoracic Society's (BTS) COPD Consortium found that only one-third of the general adult population were aware of COPD, while over 80% knew of chronic bronchitis and emphysema.(2)

Burden of the disease
COPD is common and affects 1-2% of the population, the prevalence increasing to over 7% in the over-65 age group. There are about 600,000 patients diagnosed with COPD in the UK, but this is only the tip of the iceberg, as it is likely that less than 50% of patients are currently diagnosed. COPD results in persistent and progressive symptoms that cause considerable disability, time off work and poor quality of life. One in eight acute medical admissions are for acute exacerbations of COPD, and the disease causes more primary care consultations than asthma. Deaths from COPD are currently about 30,000 per year (deaths from asthma are about 1,600 per year).(2)
Men are affected more commonly by COPD, but the last 10 years have seen a rapid rise in the number of women with the condition, due presumably to increased smoking habits.

Causes of COPD
By far the most common cause is smoking. About 20% of smokers will eventually develop COPD. Other causes include exposure to industrial dusts, particularly from coalmining. A small proportion of patients with COPD have emphysema associated with the genetically inherited deficiency of the protein a1-antitrypsin, which manifests as breathlessness that may develop in the third decade of life.
Contributory factors include low birth weight and severe respiratory infections in early life, as well as socioeconomic deprivation and a diet lacking in foods such as fresh fruit and vegetables, which contain antioxidants that may protect the lung from tobacco smoke.

Making a diagnosis
The symptoms of COPD are usually noted after the age of 50 (see Table 1). However, since the onset of symptoms is slow and insidious, patients often don't bother to consult a doctor. Indeed, in the BTS survey mentioned earlier, over 50% of patients with persistent symptoms hadn't seen a doctor about them. Some of the reasons given were that they didn't think the symptoms important or that if they went to the doctor they would be told to stop smoking and little else! As a result many patients' lung function will have fallen to below 60% of predicted by the time they first present.

[[NIP08_table1_63]]

This patient attitude and lack of knowledge of the disease create a considerable barrier to early diagnosis and the potential prevention of disease development.
A diagnosis of COPD involves taking an appropriate history, asking about cough, sputum, breathlessness and wheeze. The age of onset, variation of symptoms with time and persistence over at least three months will help to differentiate COPD from asthma. Asthmatics will have more night cough and wheeze and may have a history of symptoms in childhood.
Smoking history should include an estimate of total tobacco consumption. This is often expressed as total pack years (see Figure 1). It is unusual to have significant COPD below 20 pack years.

[[NIP08_fig1_64]]

Examination
In the earlier stages of COPD there are often no abnormal physical signs. With advanced disease there may be signs of wheeze and chest hyperinflation - reduced breath sounds and increased percussion note. There may also be cyanosis and signs of right heart failure, such as peripheral oedema.

Spirometry
Spirometry is the most accurate way of making a diagnosis and measuring disease severity. It can be performed in general practice or at the local hospital lung function unit. It is essential that the doctor or nurse performing the tests has adequate training in the technique of performing spirometry as well as the interpretation of the results.
The key measurements from spirometry are:

  • FEV(1) - forced expired volume in the first second of expiration.
  • FVC - forced vital capacity. The total volume of air that can be expired.
  • FEV(1)/FVC ratio - the percentage of air that can be exhaled in the first second and is usually about 80% of the total.

A ratio below 70% is a marker for airflow obstruction.

  • FEV(1) and FVC as a percentage of the predicted value - this is based on the gender, age and height of the subject.

A value of FEV(1) percentage predicted below 80% is abnormal and may represent airflow obstruction as long as the FEV(1)/FVC ratio is also below 70%.
Using the FEV(1) % predicted, the BTS COPD guidelines have set out severity levels, as shown in Table 2.(2)

[[NIP08_table2_64]]

Other investigations

  • Chest X-ray - useful at first presentation to exclude other diagnoses such as lung cancer, but rarely diagnostic for COPD.
  • Peak flow rate - can measure airflow obstruction but is not as accurate as spirometry.
  • Assessment of dyspnoea such as the MRC (Medical Research Council) dyspnoea score.

Reversibility testing
Bronchodilators - measuring FEV(1) before and after short-acting b-agonists or anticholinergics. An increase of greater than 200ml or a 15% increase is more suggestive of asthma. However, a lesser response does not mean that the patient will not benefit from regular bronchodilator therapy. Most patients will feel less breathless due to reduction in hyperinflation of the chest, and a clinical trial is thus always indicated.
Corticosteroids - the value of this is currently in dispute. It does help to detect the 15% of patients who show a more substantial response and thus may be candidates for long-term inhaled steroid therapy.

Treatment

Smoking cessation
This is the single most important measure for preventing progression of the disease. It is the only intervention that will slow the rate of decline in lung function with time and prolong life. It will not allow recovery of a damaged lung, although a smoker's cough is likely to clear.
Patients should always be asked about smoking during routine consultations and asked in a nonthreatening way if they had thought about giving up. Help should be regularly offered, as 70% of smokers think about quitting at some stage. All quitters may benefit from some sort of counselling. This can be supplemented with nicotine replacement therapy or bupropion.

Bronchodilators
These are the cornerstone of symptomatic treatment, and the majority of patients will benefit. Both b-agonists and anticholinergics work equally well, although the former have a faster onset of action. They should be given by the inhaled route, preferable by metered- dose inhaler, but as with asthma a suitable device should be chosen for each patient.
Long-acting bronchodilators are likely to have an increasing role as they have a positive effect on quality-of-life scores, improve symptoms and may lengthen the time between exacerbations. These actions are applicable to agents such as salmeterol as well as the new anticholinergic, tiotropium.

Inhaled steroids
The efficacy and precise indications are more uncertain. The ISOLDE study suggests that the main group to benefit are more severe patients, particularly if they are having frequent exacerbations. Steroids do not affect the rate of decline in lung function but may slow the rate of decline of quality of life and reduce exacerbations. The correct dose is uncertain, but the evidence points to only higher doses having a benefit.

Other treatments
Oral steroids should be used only in short courses for exacerbations. Influenza and pneumococcal vaccination should be offered. Pulmonary rehabilitation provides good improvement in breathlessness and quality of life. Sadly it is not readily available, but it should be in every district. Oxygen needs to be considered in more severe COPD. Assessment by a respiratory physician is essential before prescribing long-term oxygen.

Acute exacerbations
They are an important and common event in severe COPD, often leading to hospital admission and a more rapid overall deterioration in health. Acute exacerbations are treated with a combination of increased bronchodilators, antibiotics and oral steroids.

Conclusions
COPD is a common and important cause of chronic symptoms and impaired quality of life. Too often it has been dismissed as a disorder for which little can be done, apart from quitting smoking. There are many treatments that improve symptoms, and a much more positive approach is to be encouraged.

References

  1. Pauwels RA, Buist AS, Calverley PM, Jenkins CR, Hurd SS. Global strategy for the diagnosis, management, and prevention of chronic obstructive pulmonary disease. NHLBI/WHO Global Initiative for Chronic Obstructive Lung Disease (GOLD) Workshop summary. Am J Respir Crit Care Med 2001;163:1256-76.
  2. British Thoracic Society. The burden of lung disease. London: BTS; 2001.
  3. BTS COPD guidelines. Thorax 1997;52 Suppl 5:S1-28.

Resources
British Thoracic Society
17 Doughty Street
London
WC1N 2PL
T:020 7831 8778
F:020 7831 8766
W:www.brit-thoracic.org.uk
A number of useful publications about COPD, including a free booklet on spirometry, are available to download from the BTS Consortium
W:www.brit-thoracic.org. uk/publi/copd-publications.html

Further reading

Bellamy D, Booker R. COPD in primary care.  2nd ed. London: Class Publishing; 2002.