Histoplasma antigen can be detected in people with advanced HIV disease (AHD), allowing for early and accurate diagnosis of histoplasmosis. The aim of this analysis was to assess the cost-effectiveness of routine histoplasmosis screening using antigen detection, among people with AHD. We developed a decision analytic model to evaluate Histoplasma antigen screening among people with AHD. The model estimated the costs, effectiveness, and cost-effectiveness of routine screening for Histoplasma antigen compared to the current practice of no routine Histoplasma antigen screening. The model includes stratification by symptoms of histoplasmosis, severity of presentation, and estimates of 30-day mortality. Data sources were taken from the Pan American Health Organization (PAHO) Strategic Fund databases on public purchases of medicines, and published literature on treatment outcomes. Outcome measures are life years saved (LYS), costs (US dollars), and incremental cost-effectiveness ratios (ICERs). Routine Histoplasma antigen screening avoids an estimated 17% of deaths in persons with advanced HIV disease, and is cost-effective compared to no histoplasmosis screening, with an ICER of $26/LYS. In sensitivity analysis assuming treatment for histoplasmosis with liposomal amphotericin, Histoplasma antigen screening remains cost-effective with an ICER of $607/LYS. Histoplasma antigen screening among people with AHD is a cost-effective strategy and could potentially avert 17% of AIDS-related deaths. Prospective evaluation of histoplasmosis screening is warranted to determine effectiveness and treatment outcomes with this strategy.

The Caribbean continues to have high HIV prevalence globally with concurrently high mortality rates due to opportunistic Infections. This study addresses the prevalence of histoplasmosis and cryptococcosis among patients living with advanced HIV disease (AHD) in Trinidad and Tobago, focusing on the implementation of antigen-based diagnostic assays. Conducted as a cross-sectional survey across five HIV treatment sites, 199 participants with advanced HIV disease were enrolled between July 2022 and September 2023. Diagnostic testing was performed using the Clarus Histoplasma Galactomannan Enzyme Immunoassay (EIA), and the Immy CrAg^® LFA Cryptococcal Antigen Lateral Flow Assay on urine and blood samples, respectively. Results revealed that 14.6% of participants were found to be co-infected with either histoplasmosis or cryptococcosis, with histoplasmosis being more prevalent (10.5%) than cryptococcosis (4.0%). The study found no significant demographic differences between newly diagnosed and previously diagnosed participants. However, a lower median CD4 count was associated with a higher risk of fungal opportunistic infections. The findings underscore the critical role of systematic use of fungal antigen-based diagnostic assays among patients with AHD to improve the timely diagnosis and treatment of fungal infections among people living with HIV in resource-limited settings and to improve patient outcomes and survival.