Background In Italy, an estimated 13,000–15,000 people live with undiagnosed HIV infection. Italy also has one of the highest late diagnosis (CD4< 350) rates in Europe. Alternative testing strategies are urgently needed to progress towards achieving UNAIDS targets. Recently, several studies demonstrated the clinical effectiveness of opt-out emergency department (ED) testing in high-prevalence areas in Europe. In Italy, HIV testing is provided on an opt-in basis (except for antenatal care) and, in hospitals, primarily only for HIV indicator conditions. Our exploratory study assessed the potential health economic value of universal opt-out ED testing in Italy to stimulate discussion.

Material and methods We developed a closed-cohort hybrid decision-tree Markov model to assess diagnostic and treatment outcomes. Using published European evidence, intervention was based on integration in the ED electronic patient record system which triggers an HIV test request on an opt-out basis for all adult ED attendees requiring routine blood tests. Pragmatically, linkage to care (LTC) was assumed to be required for only new diagnoses, all prior diagnoses were assumed to be already engaged. The standard of care (SoC) comparator was indicator testing for the proportion of patients presenting with opportunistic infections. So far, no studies have evaluated opt-out testing in Italy, and there is no data on ED HIV prevalence. As such, ED population and diagnostic outcome profiles were primarily based on the largest, high-quality European real-world study (table 1). Treatment- and disease- outcome and cost profiles (2022 prices) were from published literature, including clinical trial reporting and Italian costing studies and databases. A lifetime horizon was assumed, and analyses were from the National Health Service perspective. Primary outcomes were discounted (3% p.a.) life years, quality-adjusted life years (QALYs), and costs.

Results For a cohort of 10,000 people presenting to the ED, out of 18.0 undiagnosed individuals, opt-out testing resulted in 15.8 additional new diagnoses and 14.5 more individuals LTC compared with SoC indicator condition testing. Universal opt-out testing is associated with improved health outcomes at higher total costs. At an HIV point prevalence of 0.52%, the ICER for the intervention was 24,680€/QALY. ED prevalence scenario analyses demonstrated that testing was cost-effective above a prevalence of 0.25% (figure 1), assuming a willingness-to-pay threshold of 30,000 €/QALY. Findings were robust across a range of scenarios and one-way sensitivity analyses.

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Abstract OC-4 Figure 1

Incremental cost-effective ratio (per-QALY) estimates for alternative ED HIV prevalence levels - vaz-pinto

Conclusions Universal opt-out ED testing could be a cost-effective strategy to increase the number of new HIV diagnoses and to improve HIV health outcomes in Italy. We likely underestimate the true benefit as our model did not consider prior-disengaged diagnoses or averted transmissions. Future research with Italian real-world data is needed to verify our findings.