Disparities in HIV/STI testing and diagnosis by population groups, geography, and age in Victoria, Australia

Background Australia is reporting increasing notifications of sexually transmitted infections (STIs). Effective control depends on timely and equitable testing. However, evidence of testing and diagnosis patterns across diverse populations is limited. This study aimed to describe STI testing and diagnosis by different demographics in Victoria. Methods A 12-month online survey in Victoria, Australia recruited individuals aged 16 years and older through the Melbourne Sexual Health Centre, the Centre for Excellence in Rural Sexual Health, targeted social media advertisements, and community digital outreach. Data was collected on self-reported STI testing (blood, swab, urine, or no test) and STI diagnosis in the past 12 months. Subgroup analyses examined differences by age, residential location, and population groups. Chi-squared tests were used to compare the proportions of STI testing and diagnosis across different subgroups. Results We included 2327 participants in this analysis. Overall, 50.2% of participants reported blood testing, 39.8% swab testing, 47.3% urine testing, and 41.0% did not have any HIV/STI test in the past 12 months. In total, 17.3% reported an STI diagnosis. Participants in regional Victoria were more likely not to test (54.0%) compared with those in greater Melbourne (40.0%). The proportion with no testing was lowest among gay and bisexual cis-men (10.5%) and highest among heterosexual cis-men (57.1%). The proportion with no testing declined significantly with age from 72.7% among those aged 16–19 years to 52.4% at 20–24 years. Conclusion Inequities in STI testing and diagnosis persist across age, population groups, and geography. Further research is needed to identify structural and behavioural barriers and to guide strategies that ensure equitable access to timely STI care.