Trends in illicit drug use and their association with HIV transmission risks from behavioural surveillance of Australian gay and bisexual men

Introduction: Investigating drug trends among Australian gay and bisexual men (GBM) is crucial for understanding levels of use and the potential for harm, including HIV transmission risk.Method: Using repeated, national, cross-sectional survey data collected between 2012 and 2021 (69,567 surveys), trends of recent (previous 6 months) and frequent (weekly) drug use were analysed, using logistic regression models. The last round of data from each jurisdiction (6709 surveys) was used to compare GBM who reported no use, infrequent (less than weekly) use and frequent (at least weekly) use of party drugs to investigate the association between party drug use and HIV transmission risk, using multinomial logistic regression models.Results: There was a significant upward trend in any recent drug use (from 58.4% in 2012 to 64.1% in 2021; p < 0.001). Frequent party drug use remained a minority practice over the period (consistently less than 3%). In cross-sectional analysis, frequent party drug users were more likely to report behaviours with HIV transmission risks, such as condomless anal intercourse without biomedical prevention strategies (30.0% vs. 13.1%; adjusted relative risk ratio [aRRR], 2.08; 95% CI, 1.24-3.47), weekly group sex (16.3% vs. 0.6%; aRRR, 12.36; 95% CI, 5.75-26.56) and more than 20 recent sexual partners (42.5% vs. 5.0%; aRRR, 21.44; 95% CI, 5.82-78.89), compared with GBM who did not use party drugs.Discussion and Conclusion: Our findings suggest that the frequent use of party drugs remains a marker of HIV transmission risk among Australian GBM, despite the increased adoption of biomedical HIV prevention strategies over the past few years.