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At the heart of general practice since 1960

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In this series GPs put their burning questions on a clinical topic to an expert – this week Dr Antony Crockett answers questions from Dr Alistair Moulds

1. Does COPD only occur in smokers?

COPD is essentially a disease of smokers and cigarette smoking is by far the most important causative factor. Each inhalation on a cigarette releases over 10 carcinogenic molecules into the lungs. Over time, these chemicals cause irreversible damage to the tissues in the lungs, and a smoking history of 10 or more pack years (20 cigarettes/day for one year = one pack year) is usual. There is presumably an additional genetic component because not all smokers will develop COPD, and about 5 per cent of patients with COPD have never smoked or been trivial smokers.

2. Are there any other causative factors?

Other factors include inhalations of xenobiotics (chemicals not naturally found in the body but which can cause harm when ingested), especially particulate pollutants in industrialised areas and wood smoke or charcoal fumes from open fires in poorly-ventilated houses, and malnutrition in utero. A rare cause is a-1 antitrypsin deficiency. Undertreated asthma may lead to irreversible airflow obstruction but the cause and the management should be of asthma not COPD, as the pathology of the two conditions is different (see diagram page 53)

3 What's the best way a GP can diagnose COPD?

Diagnosis is primarily clinical, confirmed by spirometry.

Clinical

• Age >35 years

• Smoker or ex-smoker >10 pack years

• Breathlessness on exertion

• Cough especially in mornings, often with sputum

• Frequent winter bronchitis

• Insidious onset with steadily worsening course

• Little day-to-day variation in symptom load

• Nights relatively symptom-free

• No clinical features of asthma

PLUS

Spirometry: Essential for diagnosis and assessing severity at diagnosis

• FEV1/FVC<70% •=""><80%>

Clinically significant COPD is not present if FEV1 and FEV1/FVC ratio return to normal with drug therapy or over time.

My colleague, Dr Noel O'Kelly, thought up an inventive way of remembering the various symptoms as the ‘seven bronchitic dwarfs – Smoky, Sneezy, Wheezy, Phlegmy, Puffy, Chesty and Grumpy'.

4. Is reversibility testing ever needed?

Reversibility testing is not necessary unless the diagnosis is in doubt, because:

• Asthma and COPD are often distinguishable on the basis of history and examination

• The definition of a significant change is arbitrary

• Any change in FEV1 in response to the same stimulus varies considerably from day to day, making interpretation difficult

• The response to long-term therapy is not predicted by acute reversibility testing.

Asthma is the more likely diagnosis if:

• Bronchodilator response is >400ml

• PEF diary shows significant variability

• Oral steroid trial shows >400ml response

5. With many COPD patients, I find it very difficult to stop any drug treatment they have been prescribed despite them saying it doesn't do much good as they will then say they feel a lot worse off it. How much placebo effect is there involved, especially with inhaler use?

This question highlights the importance of agreeing with the patient the outcome measures which will determine whether the introduction of any new intervention is effective. For COPD, these measures should include the following questions:

1. Has your treatment made a difference to you?

2. Is your breathing easier in any way?

3. Can you do some things now that you couldn't do at all before or do the same things but faster?

4. Can you do the same things as before but are now less breathless when you do them?

5. Has your sleep improved?

Note that any effect on lung function tests is irrelevant.

Every intervention carries a placebo effect, and inhaled therapy (especially neb-uliser therapy) is no exception. Using the above questions should minimise the placebo effect.

6. Is there any real evidence that inhaled steroids are of value? If so, does the value medically outweigh the potential side-effects?

There is extensive data that the judicious use of inhaled steroids is of immense value in managing COPD. Although the effect of the steroids may be minimal in terms of reducing airway inflammation, inhaled ster-oids improve life expectancy, improve symptoms, improve quality of life and reduce exacerbations especially in patients with more severe COPD and who have had exacerbations.

The NICE guidelines recommend that inhaled steroids should be given to all patients with an expected FEV1 less than 50 per cent predicted and who have had two or more exacerbations. They should be trialled in all patients with persistent symptoms despite adequate bronchodilator therapy and contin- ued if there is a subjective response.

In practice, the adverse effects of inhaled steroids are not usually of clinical significance, so the value of this therapy far outweighs its cost, especially when inhaled steroids are used in combination with long-acting ß-agonists.

7. Does continuing to smoke obviate the effects of medication? If so, how tough should we be in refusing to prescribe to smokers?

Smoking cessation is a key component in managing every patient with COPD. Patients who are susceptible to the effects of smoking will show an exaggerated rate of decline of lung function with age. Stopping smoking changes this rate of decline back to the same rate as in non-smokers, so although smokers who quit can never regain the lung function they have lost, they can help preserve their remaining lung function.

As life expectancy, and to a lesser extent, quality of life, are related to lung function, it clearly makes sense for all smokers to quit, no matter how severe their disease. There is some evidence that smokers respond less well to any benefits from inhaled steroids compared with ex-smokers, but less evidence of disparity when considering bronchodilators. We should be as tough as we possibly can in trying to persuade all our patients with COPD to quit, but there is insufficient evidence to withhold any treatment in continuing smokers. The exception to this is the provision of oxygen, especially long-term.

Smokers do not benefit nearly as much as non-smokers from oxygen therapy.

8. What is the value of repeating spirometry?

Repeating spirometry over time in patients with established COPD is of some but limited value. If the readings show a dramatic increase in response to intervention or time, the diagnosis of asthma should be reconsidered.

If the FEV1 declines rapidly, or symptoms seem disproportionate to the lung function readings, alternative diagnoses may need to be considered, and perhaps referral to a chest physician is indicated.

Patients whose FEV1 declines below 50 per cent predicted should be considered for chronic inhaled steroid therapy, especially if they have had two or more exacerbations. Patients whose FEV1 declines below 30 per cent should have oximetry or arterial blood gas measurements at least annually.

There seems little point in repeating spirometry in patients whose FEV1 has remained at under 30 per cent, as it will not improve, and further therapeutic intervention should be on clinical grounds rather than in response to any further deterioration in FEV1.

9. What justification is there for mucolytics?

The Cochrane Collaboration thoroughly reviewed the evidence for the use of mucolytics in COPD. The main findings were that mucolytics reduced exacerbation rates, reduced the need for antibiotics, and improved symptoms. However, most of the studies reviewed were short-term, excluded more severe patients, and those aged over 66. Nevertheless, a month's trial of mucolytics may be warranted in patients with COPD and troublesome cough and sputum, and the treatment should only be continued if there is good symptomatic improvement and no side-effects.

10. Is the overall package of care given to patients with COPD likely to prolong life or improve its quality or both? Any there any cost-benefit analyses available?

Good COPD management prolongs life and improves the quality of that life. There are many cost-benefit analyses that show the clear economic benefits of the good management of COPD. The estimated annual costs of COPD in the UK exceed £3 billion, and acute exacerbations of COPD account for over 10 per cent of hospital admissions.

11. Who should be referred to the chest clinic?

Refer to the chest clinic if there is:

• Diagnostic doubt

• Abnormal presentation (eg haemoptysis, clubbing, symptoms disproportionate to lung function deficit)

• Rapid deterioration

• Non-smokers or age <>

• Frequent infections

• Consideration of oxygen therapy or pulmonary rehabilitation

• Before committing to long-term nebulisers or oral steroids

• Rapid decline in FEV1

Alistair Moulds is a GP in Basildon, Essex

Take-home points

• Reversibility testing is not necessary unless the diagnosis is in doubt

• Be as tough as you can on smokers to stop

– but there is insufficient evidence available at present to withhold treatment if they continue smoking

• There is extensive evidence of the value of inhaled steroids in COPD

• Consider a month's trial of mucolytics

What I will do now...

Dr Moulds comments on the answers to his questions

These answers are really helpful. In particular I will now temper my therapeutic nihilism with regard to inhaled steroids and, despite my reservations, try them more often and for longer. As far as mucolytics go I am still unconvinced and will remain unlikely to initiate them in practice.

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