Longitudinal Patterns of Chronic Hepatitis B Care and Treatment Adherence in Australia: A National Linked Data Cohort Study.

Current uptake of chronic hepatitis B (CHB) treatment and care in Australia is well below target levels, leading to an ongoing burden of preventable liver disease and cancer. Understanding individual-level trajectories of care engagement and variation by sociodemographic factors is essential to guide efforts to improve access to and retention in care. This study analysed records of hepatitis B viral load (VL) testing and antiviral treatment provided through Australia's national health insurance system, which were linked to migration, death, and sociodemographic data from various government datasets. Treatment and VL testing by population group were assessed, and uptake was calculated using modelled estimates of the number living with CHB. VL testing frequency and treatment adherence based on scripts dispensed were also assessed. Of the estimated 219,800 people living with CHB in Australia in 2023, 118,334 (53.8%) received either VL testing or treatment during 2014-2023. Estimated uptake of VL testing and treatment uptake were lower among Aboriginal and Torres Strait Islander people and also varied by region of birth. Of the 81,360 who received any VL testing, only 17,352 (21.3%) received it regularly, while 31,715 (39.0%) had evidence of prior monitoring but no VL testing since 2019. The majority of those who initiated treatment continued therapy and received supply sufficient for adherence. This study shows that substantial gaps exist in CHB care in Australia, particularly in continued monitoring among those not on treatment. Disparities in uptake are evident by priority population. Re-engaging those lost to follow-up should be prioritised.