Automated STI/HIV risk assessments: Testing an online clinical algorithm in Ottawa, Canada

Despite the ongoing transmission of sexually transmitted infections (STIs) and HIV, many people became unable to access testing due to COVID-19. To address this, we created a mail-out HIV self-test kit, which could be delivered without restrictions in our region. The uptake and feedback from this project made us realize that comprehensive STI testing was being sought. To ensure testing occurred correctly-that is, it would be targeted at the persons most affected by STIs/HIV-we automated clinical decision-making. We built this model based on a 2-by-2 matrix that plots the risk of STI/HIV transmission and risk of STI/HIV exposure. The intercept of these two measures classifies a person as low, medium, or high risk. After automating this logic, 16 expert clinicians in STI/HIV care tested this system with over 400 test patient cases and refined the algorithm until it yielded the exact outcomes that these clinicians would offer patients based on guidelines. Findings of interest are that the scale of the y-axis is exponential, in that risk factors for exposure do not climb cumulatively but do so according to a quadratic equation. This helps ensure that testing services are targeted at those who are most inequitably burdened by these infections.