Chronic obstructive pulmonary disease overview: epidemiology, risk factors, and clinical presentation.

Chronic obstructive pulmonary disease (COPD) has been a major public health problem during the 20th century, and will remain a challenge for the foreseeable future. Worldwide, COPD is in the spotlight, because its high prevalence, morbidity, and mortality create formidable challenges for healthcare systems. However, there remain many ongoing, contentious issues in COPD, including the definition and staging of COPD itself. Similarly, it appears that there is no consensus as yet on how, when, and where spirometry and other tools (symptoms assessment, imaging, biomarkers, and so on) should be conducted and implemented to screen, label, and treat for COPD, if any. Our current knowledge on the epidemiology, risk factors, and clinical presentation of COPD has been reasonably well documented in several previous reviews. We aim to summarize new developments surrounding the epidemiology of COPD, both at the population and at the clinical level, in comparison with other major burden contributors, while debating old and novel risk factors. Cigarette smoking is the principal causal factor, but other factors play a role in causing and triggering COPD. Likely, the clinical presentation of COPD and its contributing phenotypes within the remainder of the 21st century will be different than the "blue bloaters" and "pink puffers" observed one or two generations ago. Hopefully, the COPD clinical course will shift to better outcomes and prognosis than in the past.