Bronchoreversibility in COPD has remained a matter of debate ever since the known association of tobacco smoking with its pathogenesis and progression. What has remained enigmatic is the observation that not all smokers demonstrate a similar susceptibility to the decline in lung function and that bronchoreversibility in COPD patients is demonstrable only in a subgroup of patients. However, it is important to identify this subgroup of patients for making treatment decisions.
It has been proposed1– that smokers with an allergic diathesis have a greater predisposition to develop severe and chronic airflow obstruction, what was popularly known as the “Dutch hypothesis.” Airway narrowing developed in hyperreactive individuals as the primary abnormality as a result of exposure to smoking or other environmental pollutants. This was contrary to the “British hypothesis,” which proposed chronic mucus hypersecretion as a marker of recurrent bronchial infections leading to chronic obstruction of the airways.2– However, the infection hypothesis has been shown to be misconstrued by the findings of several subsequent reports.3 There was no demonstrable relationship shown between exacerbations of infections or their treatment and lung function decline.3–4