ABC of COPD

Graeme P. Currie, Graeme P. Currie

• Publisher: Wiley-Blackwell
• Year: 2017
• ISBN:
  9781119212812
• Edition: 3
• Topic: Medicina
• Subtopic: Medicina polmonare e toracica

The third edition of the ABC of COPD provides the entire multidisciplinary team across both primary and secondary care with an up-to-date, easy to read and accessible account of this common lung disorder. Thoroughly updated by experienced clinicians dealing with patients with COPD on a regular basis, it discusses the entire breadth of the condition from epidemiology, causes, diagnosis, treatment and end of life care.

This practical and highly visual guide contains new and extensively updated chapters on diagnosis, smoking cessation and interventional approaches as well as expanded content on non-pharmacological and pharmacological management taking into account the most recent national and international guidelines. It also explores practical issues relating to COPD in terms of pulmonary rehabilitation, oxygen use, air travel, and end of life care.

The ABC of COPD is an authoritative and essential guide for specialist nurses, general practitioners, physiotherapists, junior doctors, front line staff working in emergency departments, paramedics, physician associates and students of medicine and its allied disciplines.

CHAPTER 1
Definition, Epidemiology and Risk Factors

Graham S. Devereux

Division of Applied Health Sciences, University of Aberdeen, Aberdeen, UK

Aberdeen Royal Infirmary, Aberdeen, UK

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OVERVIEW

• Chronic obstructive pulmonary disease (COPD) is defined by relatively fixed airflow obstruction.
• The number of individuals diagnosed with COPD is far less than the actual number thought to be affected. Prevalence increases with age and socioeconomic deprivation.
• Globally, COPD is projected to be the third leading cause of death by 2030 with the majority of deaths likely to be in low‐/middle‐income countries.
• The impact of COPD, particularly exacerbations, on health service resource is considerable.
• Risk factors for COPD include cigarette smoking, indoor air pollution (particularly close and regular exposure to combustion of biomass fuels), outdoor air pollution, occupational exposure to some dusts, vapours, irritants and fumes and α1‐antitrypsin deficiency.

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Definition

Chronic obstructive pulmonary disease (COPD) is a progressive lung disease characterised by airflow destruction and destruction of the lung parenchyma. The widely used definition put forward by the Global Initiative for Chronic Obstructive Lung Disease (GOLD) is that COPD is ‘a common preventable and treatable disease characterised by persistent airflow limitation that is usually progressive and associated with an enhanced chronic inflammatory response in the airways and the lungs to noxious particles or gases. Exacerbations and comorbidities contribute to the overall severity in individual patients’.

COPD is the preferred name for the airflow obstruction associated with the diseases of chronic bronchitis and emphysema (Box 1.1). A number of other conditions are associated with poorly reversible airflow obstruction, for example bronchiectasis and obliterative bronchiolitis. Although these conditions need to be considered in the differential diagnosis of obstructive airways disease, they are not conventionally covered by the definition of COPD. Although asthma is defined by variable airflow obstruction, there is evidence suggesting that the airway remodelling processes associated with asthma can result in irreversible progressive airflow obstruction that fulfils the definition for COPD. Because of the high prevalence of asthma and COPD, these conditions co‐exist in a sizeable proportion of individuals and can raise diagnostic uncertainty.

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Box 1.1 Definitions of conditions associated with airflow obstruction.

• COPD is a common preventable and treatable disease characterised by persistent airflow limitation that is usually progressive and associated with an enhanced chronic inflammatory response in the airways and the lung to noxious particles or gases. Exacerbations and co‐morbidities contribute to the overall severity in individual patients.
• Chronic bronchitis is defined as the presence of chronic productive cough on most days for 3 months, in each of 2 consecutive years, in a patient whom other causes of productive cough have been excluded.
• Emphysema is defined as abnormal, permanent enlargement of the distal airspaces, distal to the terminal bronchioles, accompanied by destruction of their walls and without obvious fibrosis.
• Asthma is characterised by widespread narrowing of the bronchial airways which changes in severity over short periods of time, either spontaneously or following treatment.

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Epidemiology

Prevalence

The prevalence of COPD varies considerably between epidemiological surveys. While this reflects the variation between and within countries, differences in methodology, diagnostic criteria and analytical techniques undoubtedly contribute to disparities among studies. There is no consensus as to the optimal metric of COPD prevalence. The lower estimates of prevalence are usually based on self‐reported or ‘doctor‐confirmed’ COPD and are typically 40–50% of the rates derived when spirometry is used. The underdiagnosis of COPD probably arises because many individuals fail to recognise the significance of symptoms and present relatively late with moderate or severe airflow obstruction (Figures 1.1–1.3).

Figure 1.1 Known cases of COPD may represent only the ‘tip of the iceberg’ with many cases currently undiagnosed.

Figure 1.2 Lifetime prevalence of diagnosed COPD in males and females (per 1000) resident in England 2001–2005.

Figure adapted from Simpson CR, Hippisley‐Cox J, Sheikh A. Trends in the epidemiology of chronic obstructive pulmonary disease in England: a national study of 51 804 patients. British Journal of General Practice 2010; 60(576): 277–284.

Figure 1.3 Prevalence (per 1000) of diagnosed COPD in UK men (▪) and women (●) grouped by age, between 1990 and 1997.

Reproduced from Soriano JB, Maier WC, Egger P et al. Thorax 2000; 55: 789–794, with permission of BMJ Publishing Group.

Globally, the World Health Organization (WHO) estimates that 65 million people have moderate to severe COPD. In the UK, a national study reported that 10% of males and 11% of females aged 16–65 had an abnormally low FEV₁. Similarly, in Manchester, non‐reversible airflow obstruction was present in 11% of subjects aged >45 years, of whom 65% had not been diagnosed with COPD. In the UK, an estimated 3 million individuals have COPD but only 1.2 million have a formal diagnosis. In the US, an estimate...