Investigating rates and predictors of viral blips, low-level viraemia and virological failure in the Australian HIV observational database.

Objectives: Australia has made significant progress towards achieving the UNAIDS's 95-95-95 cascade targets including HIV viral suppression. To investigate the burden of HIV viraemia, we assessed viral blips, low-level viraemia (LLV) and virologic failure (VF) in an Australian cohort.

Methods: We studied the proportion of people with viral suppression, viral blips, LLV and VF in the Australian HIV observational database (AHOD) between 2010 and 2021. The association between blips or LLV, and VF was investigated using Cox regression, and predictors of viral blips and LLV were assessed using repeated-measured logistic regression.

Results: Among 2544 AHOD participants who were in follow-up and on antiretroviral therapy (ART) from 1 January 2010 (88.7% male), 444 had experienced VF (incidence rate: 2.45 [95% CI: 2.23-2.69] per 100 person-years [PY]) during 18,125 PY of follow-up (a median of 7.6 years). The proportion of people with VF decreased over time, whereas rates of blips and LLV remained stable. Participants with blips (hazard ratio, 2.89; 95% CI: 2.31-3.61) and LLV (4.46; 95% CI: 3.38-5.89) were at increased risk of VF. Hepatitis B co-infection, longer documented treatment interruption duration, younger age and lower CD4 at ART initiation, and protease inhibitors-based initial regimen were associated with an increased risk of VF. Common predictors of blips and LLV such as higher HIV-1 RNA and lower CD4 at ART initiation, longer treatment interruption, more VL testing and types of care settings (hospitals vs. sexual health services) were identified.

Conclusions: Blips and LLV predict subsequent VF development. We identified important predictors of HIV viraemia including VF among individuals on INSTI-based regimens to help direct HIV management plans.