Cost-effectiveness of screening and treating anal pre-cancerous lesions among gay, bisexual and other men who have sex with men living with HIV.

Background: Gay, bisexual and other men who have sex with men (GBM) living with HIV have a substantially elevated risk of anal cancer (85 cases per 100,000 person-years vs 1-2 cases per 100,000 person-years in the general population). The precursor to anal cancer is high-grade squamous intraepithelial lesion (HSIL). Findings regarding the cost-effectiveness of HSIL screening and treatment in GBM are conflicting. Using recent data on HSIL natural history and treatment effectiveness, we aimed to improve upon earlier models. Methods: We developed a Markov cohort model populated using observational study data and published literature. Our study population was GBM living with HIV aged ≥35 years. We used a lifetime horizon and framed our model on the Australian healthcare perspective. The intervention was anal HSIL screening and treatment. Our primary outcome was the incremental cost-effectiveness ratio (ICER) as cost per quality-adjusted life-year (QALY) gained. Findings: Anal cancer incidence was estimated to decline by 44-70% following implementation of annual HSIL screening and treatment. However, for the most cost-effective screening method assessed, the ICER relative to current practice, Australian Dollar (AUD) 135,800 per QALY gained, remained higher than Australia's commonly accepted willingness-to-pay threshold of AUD 50,000 per QALY gained. In probabilistic sensitivity analyses, HSIL screening and treatment had a 20% probability of being cost-effective. When the sensitivity and specificity of HSIL screening were enhanced beyond the limits of current technology, without an increase in the cost of screening, ICERs improved but were still not cost-effective. Cost-effectiveness was achieved with a screening test that had 95% sensitivity, 95% specificity, and cost ≤ AUD 24 per test. Interpretation: Establishing highly sensitive and highly specific HSIL screening methods that cost less than currently available techniques remains a research priority. Funding: No specific funding was received for this analysis.