This demonstration data linkage study investigates the use of lung function testing in the diagnosis and management of chronic airways disease. It uses data from the 45 and Up Study linked to Medicare Benefits Schedule (MBS) and Pharmaceutical Benefits Scheme (PBS) data. The study shows that: - contrary to recommended guidelines, most study participants (82%) initiated on medications for managing their chronic airways disease did not have lung function testing performed within 12 months, either before or after their initial prescription - among respondents who reported having current asthma, lung function testing was only claimed for about one-quarter (26%) in a recent 3-year period and 12% had only 1 lung function test claim during that time. The evidence from this study will inform initiatives to help improve appropriate prescribing and health outcomes for people with chronic airways disease. This project also provides a demonstration of methods that could also potentially be used to fill evidence gaps associated with other chronic diseases such as diabetes, arthritis and cancer.