Asthma as a Risk Factor for Chronic Airways Disease

Summary oftheEvidence1.1:Asthma isaserious andgrowing problem forhealthinboth developed and developing countries. There are,however, important differences in reported prevalence,ranging from ashigh 11-17percent in Australia and NewZealand tozero among Eskimos andinGambia (forrefer-ences, seeMacldem, p361S). The reasons forthese varia-tions, which might relate togenetic and environmentalfactors ortodifferences inthe definition ofasthma anddiagnostic criteria, areunknown.1.2:Clinically significant asthma inchildhood isassociatedwith decreased pulmonary function and increased respira-tory symptoms inearly adulthood.’’ Moreover, some asth-matic patients, especially those with severe disease, developchronic airways disease (CAD) manifested bychronic irre-versible airways obstruction.1.3:The interaction between smoking and asthma inthepathogenesis ofCAD isunclear. Amajority ofsmokers withimpaired lung function will demonstrate airway hyperre- sponsiveness,7’ and itisknown that airway hyperresponsive-