Sex workers can be screened too often: a cost-effectiveness analysis in Victoria, Australia

Commercial sex is licensed in Victoria, Australia such that sex workers are required to have regular tests for sexually transmitted infections (STIs). However, the incidence and prevalence of STIs in sex workers are very low, especially since there is almost universal condom use at work. We aimed to conduct a cost-effectiveness analysis of the financial cost of the testing policy versus the health benefits of averting the transmission of HIV, syphilis, chlamydia and gonorrhoea to clients.

We developed a simple mathematical transmission model, informed by conservative parameter estimates from all available data, linked to a cost-effectiveness analysis.

We estimated that under current testing rates, it costs over $A90,000 in screening costs for every chlamydia infection averted (and $A600,000 in screening costs for each quality-adjusted life year (QALY) saved) and over $A4,000,000 for every HIV infection averted ($A10,000,000 in screening costs for each QALY saved). At an assumed willingness to pay of $A50,000 per QALY gained, HIV testing should not be conducted less than approximately every 40 weeks and chlamydia testing approximately once per year; in comparison, current requirements are testing every 12 weeks for HIV and every 4 weeks for chlamydia.

Mandatory screening of female sex workers at current testing frequencies is not cost-effective for the prevention of disease in their male clients. The current testing rate required of sex workers in Victoria is excessive. Screening intervals for sex workers should be based on local STI epidemiology and not locked by legislation.