HIV treatment-as-prevention and its effect on incidence of HIV among cisgender gay, bisexual, and other men who have sex with men in Australia: a 10-year longitudinal cohort study

Denton Callander; Hamish McManus; Richard T Gray; Andrew E Grulich; Andrew Carr; Jennifer Hoy; Basil Donovan; Christopher K Fairley; Martin Holt; David J Templeton; Siaw-Teng Liaw; James H McMahon; Jason Asselin; Kathy Petoumenos; Margaret Hellard; Alisa Pedrana; Julian Elliott; Phillip Keen; Jane Costello; Richard Keane; John Kaldor; Mark Stoové; Rebecca Guy

doi:10.1016/S2352-3018(23)00050-4

HIV treatment-as-prevention and its effect on incidence of HIV among cisgender gay, bisexual, and other men who have sex with men in Australia: a 10-year longitudinal cohort study

Lancet HIV. 2023 Jun;10(6):e385-e393. doi: 10.1016/S2352-3018(23)00050-4. Epub 2023 Apr 15.

Authors

Denton Callander¹, Hamish McManus², Richard T Gray², Andrew E Grulich², Andrew Carr³, Jennifer Hoy⁴, Basil Donovan⁵, Christopher K Fairley⁶, Martin Holt⁷, David J Templeton⁸, Siaw-Teng Liaw⁹, James H McMahon⁴, Jason Asselin¹⁰, Kathy Petoumenos², Margaret Hellard¹¹, Alisa Pedrana¹⁰, Julian Elliott⁴, Phillip Keen², Jane Costello¹², Richard Keane¹³, John Kaldor², Mark Stoové¹⁰, Rebecca Guy²

Affiliations

¹ The Kirby Institute, University of New South Wales, Sydney, NSW, Australia. Electronic address: d.callander@unsw.edu.au.
² The Kirby Institute, University of New South Wales, Sydney, NSW, Australia.
³ HIV and Immunology Unit, St Vincent's Hospital, Sydney, NSW, Australia.
⁴ Department of Infectious Diseases, The Alfred Hospital, Melbourne, VIC, Australia; Monash University, Melbourne, VIC, Australia.
⁵ The Kirby Institute, University of New South Wales, Sydney, NSW, Australia; Sydney Sexual Health Centre, Sydney Hospital, Sydney, NSW, Australia.
⁶ Monash University, Melbourne, VIC, Australia; Melbourne Sexual Health Centre, Melbourne, VIC, Australia.
⁷ Centre for Social Research in Health, University of New South Wales, Sydney, NSW, Australia.
⁸ The Kirby Institute, University of New South Wales, Sydney, NSW, Australia; Department of Sexual Health Medicine, Sydney Local Health District, Sydney, NSW, Australia; Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, Australia; Positive Life New South Wales, Sydney, NSW, Australia.
⁹ School of Population Health and Community Medicine, University of New South Wales, Sydney, NSW, Australia.
¹⁰ The Burnet Institute, Melbourne, VIC, Australia.
¹¹ Department of Infectious Diseases, The Alfred Hospital, Melbourne, VIC, Australia; The Burnet Institute, Melbourne, VIC, Australia.
¹² Positive Life New South Wales, Sydney, NSW, Australia.
¹³ Living Positive Victoria, Melbourne, VIC, Australia.

PMID: 37068498
DOI: 10.1016/S2352-3018(23)00050-4

Abstract

Background: Although HIV treatment-as-prevention reduces individual-level HIV transmission, population-level effects are unclear. We aimed to investigate whether treatment-as-prevention could achieve population-level reductions in HIV incidence among gay, bisexual, and other men who have sex with men (GBM) in Australia's most populous states, New South Wales and Victoria.

Methods: TAIPAN was a longitudinal cohort study using routine health record data extracted from 69 health services that provide HIV diagnosis and care to GBM in New South Wales and Victoria, Australia. Data from Jan 1, 2010, to Dec 31, 2019, were linked within and between services and over time. TAIPAN collected data from all cisgender GBM who attended participating services, resided in New South Wales or Victoria, and were 16 years or older. Two cohorts were established: one included HIV-positive patients, and the other included HIV-negative patients. Population prevalence of viral suppression (plasma HIV viral load <200 RNA copies per μL) was calculated by combining direct measures of viral load among the HIV-positive cohort with estimates for undiagnosed GBM. The primary outcome of HIV incidence was measured directly via repeat testing in the HIV-negative cohort. Poisson regression analyses with generalised estimating equations assessed temporal associations between population prevalence of viral suppression and HIV incidence among the subsample of HIV-negative GBM with multiple instances of HIV testing.

Findings: At baseline, the final sample (n=101 772) included 90 304 HIV-negative and 11 468 HIV-positive GBM. 59 234 patients in the HIV-negative cohort had two or more instances of HIV testing and were included in the primary analysis. Over the study period, population prevalence of viral suppression increased from 69·27% (95% CI 66·41-71·96) to 88·31% (86·37-90·35), while HIV incidence decreased from 0·64 per 100 person-years (95% CI 0·55-0·76) to 0·22 per 100 person-years (0·17-0·28). Adjusting for sociodemographic characteristics and HIV pre-exposure prophylaxis (PrEP) use, treatment-as-prevention achieved significant population-level reductions in HIV incidence among GBM: a 1% increase in population prevalence of viral suppression corresponded with a 6% decrease in HIV incidence (incidence rate ratio [IRR] 0·94, 95% CI 0·93-0·96; p<0·0001). PrEP was introduced in 2016 with 17·60% uptake among GBM that year, which increased to 36·38% in 2019. The relationship between population prevalence of viral suppression and HIV incidence was observed before the availability of PrEP (IRR 0·98, 95% CI 0·96-0·99; p<0·0001) and was even stronger after the introduction of PrEP (0·80, 0·70-0·93; p=0·0030).

Interpretation: Our results suggest that further investment in HIV treatment, especially alongside PrEP, can improve public health by reducing HIV incidence among GBM.

Funding: National Health and Medical Research Council of Australia.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Cohort Studies
HIV Infections* / drug therapy
HIV Infections* / epidemiology
HIV Infections* / prevention & control
Homosexuality, Male
Humans
Incidence
Longitudinal Studies
Male
Pre-Exposure Prophylaxis*
Sexual and Gender Minorities*
Victoria