Trends in incidence of HIV and other sexually transmissible infections among transgender people in Australia: a retrospective 10-year national clinical cohort study

BACKGROUND: In Australia, transgender people have largely been excluded from public health surveillance for HIV and other sexually transmissible infections (STIs). We aimed to provide a comprehensive overview of HIV and STIs among transgender people in Australia, including to investigate trends over time and risk factors. METHODS: A retrospective clinical cohort study was conducted using 10 years of health record data (between Jan 1, 2014, and Dec 31, 2023) from 87 health services across Australia. A primary transgender cohort and two comparative cisgender cohorts (gay and bisexual men, and heterosexual people) were established. Incidence was estimated using repeat testing, with the year fitted as an independent variable in Poisson regression while controlling for sociodemographic and behavioural characteristics. FINDINGS: The primary cohort comprised 7284 transgender people (4672 transgender women, 2213 transgender men, and 399 non-binary people); the comparative cisgender cohorts comprised 152 144 gay and bisexual men and 394 332 heterosexual people. Among transgender people, HIV incidence decreased by 93·9%, from 1·19 per 100 person-years to 0·07 per 100 person-years (incidence rate ratio IRR per year 0·72 95% CI 0·66-0·79). For transgender people, HIV incidence was highest among women (0·37 per 100 person-years) and lowest among men (0·20 per 100 person-years; IRR 0·54 95% CI 0·29-0·99). Transgender people overall had an HIV incidence comparable with cisgender gay and bisexual men (0·33 per 100 person-years and 0·29 per 100 person-years, respectively; adjusted IRR 0·87 95% CI 0·70-1·08), whereas HIV incidence was lower among cisgender heterosexual people (0·003 per 100 person-years; 0·01 0·01-0·01). Incidences of other STIs were generally stable among transgender people over time (33·73 per 100 person-years for chlamydia, 30·18 per 100 person-years for gonorrhoea, and 2·67 per 100 person-years for syphilis), with some distinctions by anatomical site. Among transgender people, HIV pre-exposure prophylaxis was negatively associated with incident HIV (adjusted IRR 0·40 95% CI 0·19-0·88) but positively associated with other STIs (1·38 1·31-1·46). INTERPRETATION: HIV incidence declined among transgender people in Australia, whereas other STIs were stable. To build on this success, HIV and STI policies, guidelines, interventions, and funding in Australia should more actively support transgender populations. FUNDING: Australian Department of Health & Aged Care and UNSW Health Systems Research.