The ABDS 2018 methods build on the methodological approach of the ABDS 2015 (AIHW 2016; AIHW 2019), along with methodological developments used in recent iterations of the Global Burden of Disease study (GBD 2017 and 2019). Key considerations for the ABDS 2018 were the need for:
- national estimates which were relevant to Australia, while maintaining comparability with global methods as much as possible
- Indigenous estimates which were comparable with national estimates
- sub-national estimates (state/territory, remoteness and socioeconomic group)
- comparability to 2015, 2011 and 2003 estimates to enable valid comparisons over time.
In addition, the following principles were followed to enable improvements and extensions to the methods used in the ABDS 2011 and ABDS 2015 (Box 1.1).
Box 1.1: Principles for the ABDS 2018 update
If changes were made to the ABDS disease list, methods or model inputs, estimates for previous time points were re-generated to enable true comparison over time.
Changes to key inputs (such as disability weights or reference life table) or methods (such as redistribution or comorbidity bias adjustment) must not introduce bias or compromise the consistent and systematic approach for all diseases which is the foundation of the ABDS.
Changes to models, model inputs or data sources must:
- be introduced to improve accuracy and/or defensibility and be evidence-based
- take into consideration the appropriateness of the change to previous time points. For example, changes in duration of health loss must consider whether it is appropriate to apply that change to all time points, or only the most recent time point. Changes in duration for more recent time points reflect advances in treatment; ultimately reducing the time spent in ill-health.
Variations to the list of diseases/injuries must:
- comply with criteria developed for selection of diseases and injuries in the ABDS
- maintain the existing disease list structure
- maintain mutual exclusivity
- be consistent with diseases used in the risk factor component.
Variations to the risk factors list must:
- comply with criteria developed for selection of risk factors in the ABDS (see Overarching methods and choices for risk factors)
- be consistent with the disease list (including sequelae) in terms of the associated linked diseases.