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COPD: a continuing health burden

Dr Adrian Draper
MD FRCP
Consultant Thoracic Physician
St George's Healthcare NHS Trust Honorary Senior Lecturer
St George's, University of London

Chronic obstructive pulmonary disease (COPD) is a devastating condition for many individuals in the UK and represents a major burden to our healthcare economy. This article provides an overview of COPD, focusing on diagnosis and assessing patients and the most effective treatment options

Up to one million of the UK population suffer from COPD and an estimated 27,000 individuals died from the disease in 2004; this is comparable to the number of deaths due to lung cancer. At this time, COPD accounted for 20% of respiratory hospital admissions and for over one million hospital days.1

In the UK, an overwhelming majority of COPD (90%) is attributable to tobacco smoking, which confers a six-fold risk for the disease compared to non-smokers. Despite this, not all smokers develop COPD, implying that host genetic factors also play a role in the development of this disease. Patients who develop COPD spend their lives coping with intractable breathlessness and often develop considerable disability.

Diagnosis
Patients with early disease may go unrecognised or mistaken for asthma (see Table 1) and it is important to consider the diagnosis in smokers in your practice and arrange spirometry promptly. COPD encompasses chronic bronchitis (productive cough often associated with airflow obstruction) and emphysema (lung destruction with impairment of gas exchange) and patients may have both or a dominance of either of these.

[[Tab 1 draper]]
 
COPD has been defined by spirometric criteria with a forced expiratory volume in one second (FEV1)

[[Tab 2 draper]]

Assessment/prognosis
The heterogeneity of this disease results in the impact of COPD varying between patients and is not entirely predicted by spirometry alone; indeed, patients with considerable disability from emphysema may have better-than-expected values. In assessing COPD important predictors of survival include absolute FEV1 values, degree of breathlessness, exercise tolerance and body weight. These four factors can be combined (BODE index) and provide a better prognostic indicator.2

More recently, the COPD Assessment Test (CAT) has been validated as a patient-completed eight part questionnaire which scores the impact of COPD.3 This tool may also prove to be a useful method of assessing and monitoring patients in the future as it is dependent on patient perception of the disease and not on physiological measurements.

Treatment
Smoking cessation
The treatment of COPD begins with prevention. This disease is virtually preventable by stopping the population from smoking tobacco. The recent political drive for this has seen considerable legislation to reducing tobacco consumption in the UK and Europe. This has to be welcomed and actively encouraged with all patients and the aim has to be to stop young individuals taking up a habit that leads to many years of nicotine dependence.

The population health benefits of tobacco avoidance and quitting will undoubtedly become apparent in years to come but this will not be observed for several decades. In the meantime, the health gap between the most and least affluent in UK society is likely to widen because of the difference in prevalence of smoking among these groups. In a recent Department of Health consultation it was noted that the prevalence of smoking in individuals with an annual income of >£55,000 was 15% compared with a higher than average 29% in those with an income of

Pharmacological therapies
Once COPD is established, the disease is essentially irreversible. Progressive breathlessness occurs with intermittent exacerbations and decline in lung function, culminating in type 2 respiratory failure (with hypoxia and carbon dioxide retention). There is no curative treatment, and current medications are aimed at symptom relief and exacerbation reduction.

A treatment escalator based on spirometric severity and symptoms is proposed by the NICE guidance for the management of COPD5 beginning with short- acting bronchodilators (β2 agonists and anticholinergics) and progressing to long-acting bronchodilators as monotherapy (anticholinergics) and β2 agonists combined with inhaled corticosteroids. There are now several good-quality randomised clinical trials that support the use of these inhaled therapies - demonstrating reduced exacerbations and improved quality of life scores when compared with placebo in patients with moderate or severe disease. Theophylline can be considered if patients remain symptomatic.

Other therapeutic strategies
Patients with significant breathlessness should be referred for pulmonary rehabilitation, for which there is an established evidence base. Lung volume reduction surgery has been considered for select patients with localised emphysema and lung transplantation is a possibility in some patients.
Pneumococcal and annual influenza vaccines should be offered to patients to help reduce infectious exacerbations. Oxygen requirements should be screened for with pulse oximetry and when saturations fall below 92% arterial/capillary blood gas analysis should be performed.

Long-term oxygen therapy (LTOT) for at least 16 hours per day with a view to correcting hypoxia has been shown to prolong life in COPD. It is important to note that oxygen has no role in patients with COPD who do not have significant hypoxia at rest or on exertion. Many patients and their carers have a misunderstanding of the role of LTOT, believing it is used primarily for symptomatic relief rather than longer-term prognostic benefits. Despite this, it is the author's experience that some patients undoubtedly benefit symptomatically from LTOT; but whether this is a true physiological or psychological effect is open to debate.

Patients with a chronic productive cough can be offered mucolytic therapy to aid expectoration. Consideration should also be given to the general effects of COPD, including dietary supplements if underweight and detection and treatment of depression, which is often overlooked.  

Non-invasive ventilation
Despite the aforementioned treatments, patients still suffer exacerbations that result in hospital admission, with some 80% being attributable to infections (bacterial and viral) and the remainder being due to a reduction in temperature or no obvious cause. Patients do not like hospitalisations with exacerbations - they are unpleasant and many take several weeks to months to recover to their baseline state. Some of these patients are now treated with non-invasive ventilation (NIV) with a benefit in survival from the acute exacerbation.

It should be noted that an admission requiring NIV predicts further admissions for this treatment and also a mortality of nearly 80% during the following year. NIV is sometimes used with good effect in outpatients with COPD and chronic type 2 ventilatory failure. There are no current guidelines as how to select COPD patients who are suitable for domiciliary NIV; individual cases have to be treated on their merits.

Palliative care
Palliative care is vital for patients with end-stage COPD in terms of symptom relief using benzodiazepines and tranquillisers as necessary. Planning the ceiling of treatment with an honest discussion regarding interventions when the patient has capacity to make an informed decision is desirable, but is less often a reality. Sadly, decisions about such treatments are often made out of hours by junior hospital doctors for patients who present acutely unwell and this can lead to inappropriate escalation of therapy which may be futile and is not always in the patient's best interest. This judgement requires experience and careful attention as some patients also have a better prognosis than was previously thought and, again, may do better with escalation of therapy.

Conclusion
COPD will remain a leading cause of mortality and morbidity for some years to come in the UK. It is also becoming a major global problem with increasing tobacco consumption in developing countries.

References
1. British Thoracic Society. The Burden of Lung Disease, 2nd ed. London: BTS; 2006.
2. Celli BR, Cote CG, Marin JM et al. The body-mass index, airflow obstruction, dyspnea, and exercise capacity index in chronic obstructive pulmonary disease. N Engl J Med 2004;350(10):1005-12.
3. Jones PW, Harding G, Berry P, Wiklund I, Chen W, Kline Leidy N. Development and first validation of the COPD Assessment Test. Eur Respir J 2009;34(3):648-54.
4. Department of Health. Consultation on the future of tobacco control. London: DH; 2008.
5. National Institute for Health and Clinical Excellence (NICE). Chronic obstructive pulmonary disease. Management of chronic obstructive pulmonary disease in adults in primary and secondary care. London: NICE; 2004.