Impact and Cost-effectiveness of Regular Self-digital Anorectal Examination on Syphilis Among Gay, Bisexual, and Other Men Who Have Sex With Men: A Mathematical Modeling Study

Abstract

Background. Rising syphilis incidence among Australian gay, bisexual, and other men who have sex with men (GBMSM) requires new early detection strategies. Regular self-digital anorectal examination (self-DARE) may facilitate syphilis identification, potentially reducing transmission. We evaluated its population-level impact and cost-effectiveness in controlling syphilis among Australian GBMSM. Methods. We developed an integrated transmission-dynamic and health-economic model, calibrated with 2012–2022 Australian GBMSM data. Over a 10-year period (2025–2034), we compared the base case with two scenarios: recommending self-DARE to men with higher sexual activity (“only high group”) or to all individuals (“both groups”). We assessed changes in incidence, incremental cost-effectiveness ratios (ICERs), and benefit-cost ratios. Results. The base case projected 110 501 new infections over 10 years. The “only high group” strategy averted 57 115 infections (51.7%) and was cost saving (negative ICER), with a benefit-cost ratio of 2.5. The “both groups” strategy averted more infections (58 216; 52.7%) but was less economically efficient (benefit-cost ratio: 1.6), though also cost-saving. Sensitivity analyses indicated that improving self-DARE sensitivity enhanced its performance. Conclusions. Self-DARE could effectively and cost-effectively reduce syphilis among GBMSM, particularly when focused on men with higher sexual activity. Further empirical research is needed to confirm its feasibility and effectiveness.