Epidemiological investigation of chronic lung disease within the Australian Burden of Lung Disease (BOLD) study

Abstract

Background: Chronic lung diseases have become one of the greatest global public health challenges, but important gaps in knowledge about it, especially COPD still exist. These include, data on asthma+COPD in general populations and the univariate associations of breathlessness, including lung functions in Australia are limited. Also, there is a lack of population data on the burden of COPD defined by GOLD spirometry criteria and information on Preserved Ratio Impaired Spirometry (PRISm) in Australia is scarce. This thesis aims to better understand the characteristics of chronic lung disease, especially COPD, in Australian adults.

Methods: Chapter 1 provides a literature review of chronic lung disease. The analyses in Chapters 2-5 used data from BOLD Australia, a cross-sectional study that included randomly selected adults aged ≥40 years from six sites in Australia. Characteristics among individuals with self-reported asthma and/or COPD in Australia were compared in Chapter 2. Clinical characteristics and spirometry results were compared for breathlessness in Chapter 3. The health burden of individuals within each GOLD spirometry grades were explored in Chapter 4. The prevalence and characteristics of PRISm in Australian adults were investigated in Chapter 5.

Results: This thesis reports that individuals with asthma+COPD had more frequent respiratory symptoms, greater airflow limitation, and increased health burden than those with either disease alone; breathlessness was associated with impaired spirometry results and being indigenous Australians; higher GOLD spirometry grades were related to greater health burden and poorer quality of life; PRISm population was highly symptomatic individuals with significant health burdens.

Conclusions: These findings expand our understandings of chronic lung diseases in Australia. Furthermore, future assessment, including conducting new population studies and validation of long-term outcomes of chronic lung disease are essential.