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Introduction

Chronic obstructive pulmonary disease (COPD) is defined as a disease state characterized by airflow obstruction that is not fully reversible and for which there is no other explanation for the obstruction. The obstruction is usually progressive and associated with an abnormal inflammatory response of the lungs to noxious particles and gas. Unlike earlier definitions, this definition does not mention emphysema or chronic bronchitis. According to criteria set by the Global Initiative for Obstructive Lung Disease,1 airflow obstruction is present when there is a reduction of the postbronchodilator FEV1/FVC ratio below 0.7 and its severity is graded by the percentage of the postbronchodilator FEV1 of the predicted normal FEV1 (Table 40-1). However, 0.7 as the cutoff value for the FEV1/FVC ratio has been controversial as it may be too high for all age groups and lead to misdiagnosis of COPD in healthy middle-aged and older individuals.2 Alternatively, use of the lower limit of normal (LLN) for the FEV1/FVC ratio has been recommended,3 but it is uncertain whether this criterion improves the detection of clinically significant COPD or prognosis in elderly individuals.4,5 Classification of COPD by GOLD has undergone further refinement recently with addition of self-reported severity of dyspnea and history of COPD exacerbations.1 Chapter 42 comments further about risk stratification.6

Table 40-1Classification of Airflow Limitation in Patients with FEV1/FVC < 0.7

Epidemiology

COPD is a major health problem worldwide.7,8 Its prevalence is being recognized increasingly in countries at all levels of development.9 An ever-increasing number of smokers and an expanding number of elderly people are major factors in the surge in the worldwide prevalence of COPD. In a study from Canada, 27.6% of individuals reaching the age of 80 were diagnosed with COPD by a physician over the preceding 14 years.10 In large areas of the world where indoor air pollution is generated by burning biomass for heating and cooking, COPD is prevalent among nonsmokers, especially women.11 Moreover, COPD is not restricted to smokers in developed countries. Of 4291 never-smokers over age 40, involving 14 developed countries, 5.6% met criteria for moderate to severe COPD, of whom 81.2% were undiagnosed.12

At present, COPD is the third ...

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