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Hippocrates may well have appreciated the significance of the presence of emphysema, but it was not until the 17th century that Bonet1 described the larger lungs of those with emphysema, to which he attributed their breathlessness. In 1821, Laennec connected emphysema to ageing, when he ascribed a subtly different definition to emphysema, describing it as “a breakdown of tissue in the parenchyma of the lungs as opposed to air trapped in the alveoli due to obstruction as occurs in asthma and chronic bronchitis” essentially considering emphysema to be an ‘independent finding’ to obstructive lung disease, although at postmortem.2 Fast forward 200 years, and one could argue that even in 2016 the significance of emphysema on a CT scan in someone who does not have airflow obstruction or clinical symptoms of breathlessness is unclear.
Even the significance of emphysema among people with COPD and the association between emphysema and smoking are obscure. Around half of patients with COPD do not have significant emphysema,3 and up to 10% of never smokers have evidence of emphysema at postmortem.4 On the …