Prevalence

Estimates of the prevalence of COPD depend on the definition and criteria used. Estimates based on the presence of airflow limitation are the most accurate, since symptoms and self-report or clinician diagnosis lack sensitivity and specificity.

A postbronchodilator FEV1/FVC <70%, in combination with an FEV1 <80% pred, in an individual with cough, sputum production or dyspnoea and exposure to risk factors confirms the diagnosis [1].

The best prevalence data available at present come from the third NHANES (NHANES III), a large national survey conducted in the USA between 1988 and 1994. In the USA, for those aged 25-75 yrs, the estimated prevalence of mild COPD (defined as FEV1/FVC <70% and FEV1 ≥80% predicted) was 6.9% and of moderate COPD (defined as FEV1/FVC <70% and FEV1 ≤80% predicted) was 6.6%. The prevalence of both mild and moderate COPD was higher in males than females, in Whites than in Blacks, and increased steeply with age [2].

In the NHANES III study, COPD (defined as the presence of airflow limitation) was estimated to be present in 14.2% of current White male smokers, 6.9% of exsmokers and 3.3% of never-smokers. Among White females, the prevalence of airflow limitation was 13.6% in smokers, 6.8% in exsmokers and 3.1% in never-smokers [2].

Less than 50% of individuals with COPD based on airflow limitation have a doctor’s diagnosis of COPD and, somewhat surprisingly, this is not only true for mild COPD [3].

Morbidity

Morbidity data include physician visits, emergency department visits and hospitalisations. COPD databases for these outcome parameters are less readily available and usually less reliable than mortality databases.

The limited data available indicate that morbidity due to COPD increases with age and is still greater in males than females.

Risk of hospital admission increases with decreasing lung function and when chronic respiratory symptoms are present [4]. Admission rates are also increased in patients with lower socioeconomic status [5].

Morbidity is likely to increase in the future, not only due to changes in smoking habits but also because of ageing of populations [6].

Mortality

Mortality data for COPD are inaccurate because of inconsistent use of terminology.

COPD death rates are very low under the age of 45 yrs and increase steeply with age.

COPD is the fourth leading cause of death worldwide and is estimated to be the third leading cause of death by 2020 [7].

Recently, the most important change has been the huge increase in the COPD death rate in females that has occurred in the USA over the last 20 yrs: from 20.1 out of 100,000 in 1980 to 56.7 out of 100,000 in 2000; as compared to the values in males, 73.0 out of 100,000 in 1980 to 82.6 out of 100,000 in 2000 [2].

Economic Burden

COPD is a more costly disease than asthma. The direct costs of COPD are the value of healthcare resources devoted to diagnosis and medical management of the disease. Indirect costs reflect the monetary consequences of disability, missed work, premature mortality and caregiver or family costs resulting from the illness [8].

When medical costs for COPD are compared across countries for which data are available, there is surprising similarity. When adjusted to 1993 US dollars, the costs per capita (in the entire population) are: $65 for the UK, $60 for Sweden and $87 for the USA. Distribution of the costs in different countries, however, is different. In the USA, for example, ~75% of the costs for COPD are for services associated with exacerbations, such as hospitalisation [8].