Epidemiology

Europe, as defined by the World Health Organization (WHO), has a population of approximately 750 million in 54 countries, among which there are large differences in population structure and health services and great environmental heterogeneity. Europe should therefore be an ideal region in which to explore environmental as well as genetic influences on the mortality, prevalence, incidence and hospital admission rate of COPD. Several large single-centre population studies of COPD in Europe have been in progress for some time: since 1972 in Oslo, Norway; since 1976 in Copenhagen, Denmark; since 1980–1982 in the Po river delta, Italy; and since 1985 in northern Sweden and in Bergen, Norway. In addition, multicentre surveys of COPD in single countries have been conducted in Switzerland and Spain,  and studies have been coordinated across many European countries simultaneously in the European Community Respiratory Health Survey (ECRHS) and the Burden of Obstructive Lung Disease (BOLD) study. However, estimates of mortality, hospital admissions, prevalence and incidence are still lacking from many European countries in 2012.

The data in this chapter are based on the International Classification of Disease, 10th revision (ICD-10) codes J40–J44 and J47, chronic obstructive pulmonary diseases and bronchiectasis (which have much in common). The diagnostic codes J45 and J46 (asthma and status asthmaticus) have generally not been included. Differences in coding may be a cause of variations both within regions of a country and between countries, as combinations of these diseases are not uncommon. Some physicians responsible for recording cause of death still use the diagnosis of asthma/status asthmaticus instead of COPD and both under- and overdiagnosis of COPD are frequent on death certificates as well as in clinical practice.

Mortality

Overall, the COPD mortality rate for men and women in Europe, age-standardised to the European Standard Population, is about 18 per 100 000 inhabitants per year. The variation of age-standardised mortality rates is, however, more than 10-fold among the 39 countries that provided data on mortality to the WHO (figure 1). Data are scarce from countries in eastern Europe. There is a general trend for countries with higher prevalence of cigarette smoking to have higher mortality from COPD. According to the WHO, in 1997, COPD was the cause of death in 4.1% of men and 2.4% of women in Europe. However, in Denmark, deaths due to COPD are more frequent in women than in men.

It is noticeable that over a short period of time there has been a substantial decline in death rates from many causes, including cardiovascular disease, but for COPD mortality, this tendency to decline started much later in some countries.

Hospital admission

Hospital admission rates for COPD are available for 31 European countries, with the majority of data coming from western Europe. The average age-standardised admission rate for COPD is about 200 per 100 000 people per year, being highest in Denmark, Hungary, Romania, Turkey, Macedonia, Austria, Germany, Belgium, Spain and Ireland, and lowest in Switzerland, France, Portugal, Slovenia, Croatia and Latvia. The variation in admission rates is as high as 10-fold between European countries (figure 2). Hospitalisation rates for COPD are heavily dependent on the average age of the population in the community and the organisation of emergency units, as well as the availability of hospital beds. In western and central Europe there has been a steady decrease in the overall number of hospital beds as a result of changes in the structure of healthcare. Predictors of exacerbations and hospital admissions for COPD include a previous history of exacerbations, more severe disease, impaired quality of life and the presence of comorbidities. In several countries in northern Europe, the admission rates are higher in women than men. A study including 234 hospitals in the UK showed an in-hospital mortality of 7% and a 90-day mortality of 15% following admission for COPD exacerbations. More than 50% of COPD patients discharged from hospital after an exacerbation are readmitted within a year.

Incidence and prevalence

Precise estimates of incidence of spirometry-defined COPD are lacking for most countries in Europe. A population-based study in Norway showed an overall incidence of 1% per year in 18–74 year olds during 9 years of follow-up. The incidence did not vary according to sex; it increased with increasing age; and it was 10 times higher in smokers than in never-smokers. More than 100 studies of COPD prevalence have been published since the 1970s and most estimates from large-scale studies are between 5% and 10%. These studies vary in survey methods, diagnostic criteria, analytical approaches and age distribution of the populations examined, making comparison between study results difficult.

The international, population-based BOLD study aims to use standardised survey methods and a spirometric criterion for COPD, enabling direct comparison between study populations. The prevalence of spirometry-defined COPD (FEV1 /FVC < 0.7, FEV1 <80% of predicted value) is about 10%. It varies considerably between European countries (figure 3). This may partly be due to small sample sizes in the studies and partly due to age distribution and different environmental exposures. The prevalence of COPD is higher in men than in women (figure 3). All studies show a clear increase of prevalence with age. In people aged >70 years, the prevalence of COPD is about 20% in men and 15% in women.

 

See the entire Obstructive pulmonary disease Chapter