COPD

Definition and diagnostic criteria

COPD or chronic obstructive pulmonary disease is characterised by chronic airway obstruction resulting in airflow limitation that is not fully reversible.

COPD primarily affects people aged over 45. Its main characteristic is a progressive and irreversible decline of pulmonary function, usually associated with smoking, its main risk factor.

The ERS diagnostic criteria for COPD include the following symptoms: coughing, sputum production and/or dyspnoea, as well as a history of exposure to risk factors for COPD. The diagnosis is confirmed by a post-bronchodilator FEV1/FVC < 0.7 in spirometry, as sign of the airflow limitation that is not fully reversible.

According to the symptoms and the spyrometric parameters, the COPD has four stages, from mild (stage I) to very severe (stage IV).

ICD classification

The GOLD guide to COPD emphasizes the distinction between chronic bronchitis, emphysema and asthma. As a diagnostic category, the term "chronic airways obstruction" was first established in 1979 with the introduction of ICD-9, replacing 'chronic bronchitis and emphysema'.

The current, ICD-10 classification classifies COPD under "Chronic lower respiratory diseases" (J40-J47). Apart from the group 'Other chronic obstructive pulmonary disease' (J44), several other groups are included, such as: 'Bronchitis, not specified as acute or chronic' (J40), 'Simple and mucopurulent chronic bronchitis' (J41), 'Unspecified chronic bronchitis' (J42), 'Emphysema' (J43), 'Asthma' (J45), 'Status asthmaticus' (J46), and 'Bronchiectasis' (J47). This classification came into use in WHO Member States as from 1994.

The presumed underestimation of COPD prevalence and mortality, reflects the variations and changes in terminology, diagnostic criteria and ICD coding (European Lung White Book, 2003).

COPD prevalence is underestimated

Epidemiologic studies examining the incidence of respiratory symptoms show that COPD is a major health problem in Europe. They also indicate that COPD is often under-diagnosed, so that the true prevalence rates and the burden of disease may be much higher than the currently available data suggest (Pauwels, 2000; Wouters, 2003; Halbert et al., 2003).

Estimates of COPD prevalence rates vary widely, from 0.2% to 18.3%, partly as a result of real differences in prevalence among countries and regions, and partly because of other factors. These factors include the method by which the prevalence is estimated (expert opinion, patient-reported diagnosis, symptom-based or spirometry-based), the definition of COPD that was used, age and smoking status of the population included, etc. Some well-designed studies have found a measured prevalence of COPD in Europe between 4% and 10% of adults (Halbert et al., 2003).

Spirometry-based estimates of COPD prevalence in selected EU countries are taken from a study (Halbert et al., 2003) that has recently summarised the available prevalence data on the world scale. Only 32 sources in 17 countries could be identified, that estimated COPD prevalences for a population and clearly described the methods that were used. Poor comparability of the COPD prevalence data hinders meaningful comparisons among EU countries.

Factors determining COPD prevalence

The COPD prevalence increases with age. Since COPD is a low-progressive disease, it is easier to find it in elderly people. The rapid decline of pulmonary function, which is typical of COPD, can be associated with the physiological decline of the function itself.

Lower socio-economic status, independent of smoking behaviour, negatively affects the pulmonary function and thus also the susceptibility to, and the severity of COPD (Pauwels, 2000).

Men have a higher prevalence than women, due to the greater smoking exposure. Among non-smokers women have a higher presence of COPD than men. Research suggests that about 85% of aged never-smokers with COPD are women (Massaro & Massaro, 2004).

Trends in COPD prevalence

Smoking is the primary risk factor for developing COPD, and the COPD prevalence trends generally follow the tobacco smoking behaviour in the population. However, some countries record a low COPD prevalence in spite of high rates of smoking. Data obtained by objective measurements (spirometry) suggest that prevalence underestimates are responsible for this discrepancy (Halbert et al., 2003).

With smoking prevalence rates still increasing among European women, it is likely that COPD will in particular affect that segment of population in the near future.

The expected ageing of the EU population will further contribute to the burden of COPD in the coming decades.

More comparable data are required to assess the extent of COPD morbidity and its future trends in the EU.

COPD mortality is expected to rise

The Global Burden of Disease Study estimates that by the year 2020, COPD will move from the sixth to the third-leading cause of death worldwide.

COPD mortality rates vary from less than 25 to more than 75 per 100,000 inhabitants in various European countries (European Lung White Book, 2003). This is reflected as considerable differences in mortality from chronic respiratory diseases among EU countries (see Mortality due to chronic lower respiratory diseases, Mortality from COPD in the EU-27).

Male mortality rates are three times higher than those for women in EU countries (European Lung White Book, 2003). The risk factors involved in the aetiology of COPD may explain gender differences. COPD is mainly associated with smoking, which is still more common among men, but also with work-related risks (mining, steel making or farming).

Variability in coding practices between countries (Cooreman et al., 1990,97) and between succeeding ICD-versions (Fuhrman et al., 2006) introduced some uncertainty in assessing the reliability of the COPD mortality data.

Trends in COPD mortality

COPD mortality rates are relatively insensitive to intermittent or short-term smoking cessation.

An increase in COPD mortality in Europe is likely, due to the increase in rates of smoking among women, and to the ageing of European population (European Lung White Book, 2003).

The assessment of COPD mortality trends is likewise very much affected by changes in coding and diagnostic practices over time.

COPD significantly reduces quality of life

Shortness of breath, chronic coughing, wheezing, weight loss, heart failure in later stages and exacerbations that often require hospitalisation, contribute to the generally poorer quality of life of COPD patients.

COPD ranks high as a cause of disability

In 1990 COPD was the 12th most common cause of disability in the world. The World Health Organization predicts that by 2020 COPD will rank 5th as a cause of disability, causing 4% of the total DALYs lost. Moreover, it will rise from its current ranking as the 6th most common cause of death to the 3rd (Murray & Lopez, 1997c).

This dramatic increase is due to several factors (Barnes, 2000):

• increase in smoking prevalence (industrialised countries);
• increase in environmental pollution (developing countries);
• reduction in mortality from other causes in industrialised countries (especially cardiovascular diseases);
• reduction in mortality from infectious diseases (developing countries).

COPD has high societal costs

The total financial burden of lung disease in Europe amounts to nearly €102 billion. COPD accounts for almost one half of this figure (European Lung White Book, 2003)

An economic analysis of data from the Confronting COPD International Survey study, a large-scale survey conducted in North America and Europe, has shown that COPD has a high economic impact on society. The total societal costs of COPD per patient range between €3,538 in Spain and €1,024 in the Netherlands. Lost productivity due to COPD accounted for 67% of overall costs in France, 50% in the Netherlands and 41% in the UK. The costs to the healthcare system per patient - mainly due to exacerbations and subsequent hospitalisations - range from €3,238 in Spain to €614 in the Netherlands and €530 in France. These data not only provide information about the actual costs, but also about the differences in disease management. The burden of COPD can be reduced through policies aimed at better evaluation, diagnosis and management of COPD, including improved prevention and treatment of acute exacerbations (Wouters, 2003).

Tobacco smoking

Tobacco smoking causes 80% to 90% of COPD cases. Smokers are more than ten times as likely to die from COPD than non-smokers (US DHHS, 2004). Chemicals found in tobacco smoke stimulate inflammation in the lungs, leading to destruction of the alveoli and narrowing of the airways. While smoking is related to most COPD cases, only 15% to 20% of smokers develop the disease.

Environmental factors

Exposure to outdoor and indoor air pollutants increases the prevalence of COPD by an estimated 2% for each 10 g/m3 increase in particulate matter (Künzli, 1997). The use of biomass fuels (e.g. use of wood for cooking and heating) increases the risk of COPD by three to four times, contributing significantly to COPD prevalence, especially in rural regions (Halbert et al., 2003).

Age

COPD is rarely found below the age of 40 (Halbert et al., 2003). Lung function deteriorates with age. Ageing may therefore increase the susceptibility for the development of COPD and its exacerbations. As previously stated, COPD prevalence is higher in elderly people; it is not the physiological decline of the function which predispose to COPD.

Sex

Sex does not seem to have a specific meaning in the development of COPD in the general population, except when related to smoking behaviour. Male smoking rates still exceed female, although prevalence rates for European women are increasing while male rates have either reached a plateau or are decreasing. It is likely that the COPD prevalence will follow this pattern.

Recent research indicates that estrogen plays a role in maintaining the lung function in women, putting postmenopausal women at higher risk of developing COPD, having a severe form, and dying from COPD. This may explain the higher prevalence of COPD among older women non-smokers, compared to the male non-smoking population (Massaro & Massaro, 2004).

Genetic factors

A rare inherited condition and the only currently known genetic risk factor for COPD, alpha1-antitrypsin (AAT) deficiency is due to the inability to produce enough of the lung-protective protein AAT in the liver. Severe AAT-deficiency leads to emphysema at an early age.

Socio-economic inequalities

Deprivation, measured by income and education can negatively affect lung function, independently of smoking. Underlying reasons include childhood infections, occupational exposure and poor housing conditions. Impaired lung function can increase the susceptibility to COPD and its exacerbations (Pauwels, 2000).

Primary prevention consists mainly of refraining from smoking

The most prominent and effective preventive measure concerning COPD is refraining from smoking and avoiding environmental tobacco smoke (ETS). An improved indoor and outdoor air quality, including reduction of the use of biomass fuel for cooking and heating, would further contribute to the reduction of the COPD prevalence in the world.

Secondary prevention: COPD is still under-diagnosed and under-treated

COPD appears to be under-diagnosed and under-treated in most countries. Better evaluation and diagnostic practices, as well as disease management, implementation of guidelines and awareness-raising among general public and risk groups may improve the outcomes for COPD.

The World Health Organization recommendations for the COPD management include four main components:

• assess and monitor disease;
• reduce risk factors;
• manage stable COPD;
• manage exacerbations.

Treatment options

Currently, there are three treatment options mainly used in the EU: anticholinergic bronchodilators, ß2-agonists, and the inhalative corticosteroids. Results from three large trials (ISOLDE, EUROSCOP and CCHS) have shown that inhaled corticosteroids do not improve the COPD symptoms as expected and the benefits are far less significant than in asthma patients (Pauwels, 2000).

Some researchers describe preliminary positive effects of Omega-3 Polyunsaturated Fatty Acids (PUFA) as a nutritional supplement on chronic inflammation in airways, the underlying cause of COPD (Matsuyama et al., 2005).

Disease-specific mortality

Life expectancy

Healthy life expectancy

Smoking

Smoking policies

Children's Health and the Environment

Eurostat Statistical Office of the European Communities

HFA-DB WHO Health for all database

Health-EU Portal, other non-communicable diseases

ERS European Respiratory Society

GOLD The Global Initiative for Chronic Obstructive Lung Disease

IMCA Indicators for Monitoring Chronical Obstructive Pulmonary Disease (COPD) and asthma in the EU

IMCA II Indicators for Monitoring COPD and asthma in the EU (health information 2005)

EHRM European Health Risk Monitoring Project

Spirometry-based estimates of COPD prevalence in a number of countries for men, women and total, 2003

Mortality (SDR) due to chronic lower respiratory diseases for all ages, male, female and total; asthma subtracted, in a number of countries, 2000

Mortality (SDR) from COPD for all ages for selected countries, 2000 (interactive)

Mortality (SDR) from COPD, total in the EU-27, 2003

Mortality (SDR) from COPD, for men in the EU-27, 2003

Mortality (SDR) from COPD, for women in the EU-27, 2003

FEV1 = Forced Expired Volume in 1 second, FVC = Forced Vital Capacity

^a = Lange et al., 1989 ^b = Dickinson et al., 1999 ^c = Isoaho et al., 1994

^d = von Hertzen et al., 2000 ^e = Viegi et al., 2000 ^f = Marco Jordán et al., 1998

^g = Peña et al., 2000