Impact of increased antiretroviral therapy use during the treatment as prevention era in Australia.

ABSTRACT

BACKGROUND: We analysed the impact of increased antiretroviral therapy (ART) on HIV epidemiology and healthcare costs in Australia during the 'Treatment-as-prevention' and 'Undetectable equals Untransmissible (U=U)' eras. METHODS: We conducted a retrospective modelling analysis between 2009 and 2019 to calculate the potential impact of early initiation of ART and treatment-as-prevention on HIV among gay and bisexual men (GBM). The model incorporates the change in the proportion diagnosed, treated, and virally suppressed, as well as the scale-up of oral HIV pre-exposure prophylaxis (PrEP) and the change in sexual behaviour during this period. We simulated a baseline and a no ART increase scenario and conducted a costing analysis from a national health provider perspective with cost estimates in 2019 AUD. RESULTS: Increasing ART use between 2009 and 2019 averted an additional 1624 [95% percentile interval (PI) 1220-2099] new HIV infections. Without the increase in ART, the number of GBM with HIV would have increased from 21 907 (95% PI 20 753-23 019) to 23 219 (95% PI 22 008-24 404) by 2019. HIV care and treatment costs for people with HIV increased by $296 (95% PI $235-367) million AUD (assuming no change in annual healthcare costs). This was offset by a decrease in the lifetime HIV costs (with 3.5% discounting) for those newly infected of $458 (95% PI $344-592) million AUD, giving a net cost saving of $162 (95% $68-273) million AUD (and a benefits-to-cost ratio of 1.54). CONCLUSIONS: Increasing the proportion of Australian GBM on effective ART between 2009 and 2019 likely resulted in substantial reductions in new HIV infections and cost savings.