AbstractBackground:The aim of this study was to calculate the cost-effectiveness of the EmERGE Pathway of Care for medically stable people living with HIV in the Hospital Capuchos, Centro Hospitalar Universitário de Lisboa Central (HC-CHLC). The app enables individuals to receive HIV treatment information and communicate with caregivers.Methods:This before-and-after study collected the use of services data 1 year before implementation and after implementation of EmERGE from November 1, 2016, to October 30, 2019. Departmental unit costs were calculated and linked to mean use of outpatient services per patient-year (MPPY). Annual costs per patient-year were combined with primary (CD4 count; viral load) and secondary outcomes (PAM-13; PROQOL-HIV).Results:Five hundred eighty-six EmERGE participants used HIV outpatient services. Annual outpatient visits decreased by 35% from 3.1 MPPY (95% confidence interval [CI]: 3.0–3.3) to 2.0 (95% CI: 1.9–2.1) as did annual costs per patient-year from €301 (95% CI: €288–€316) to €193 (95% CI: €182–€204). Laboratory tests and costs increased by 2%, and radiology investigations decreased by 40% as did costs. Overall annual cost for HIV outpatient services decreased by 5% from €2093 (95% CI: €2071–€2112) to €1984 (95% CI: €1968–€2001); annual outpatient costs decreased from €12,069 (95% CI: €12,047–€12,088) to €11,960 (95% CI: €11,944–€11,977), with 83% of annual cost because of antiretroviral therapy (ART). Primary and secondary outcome measures did not differ substantially between periods.Conclusions:The EmERGE Pathway produced cost savings after implementation—extended to all people living with HIV additional savings are likely to be produced, which can be used to address other needs. Antiretroviral drugs (ARVs) were the main cost drivers and more expensive in Portugal compared with ARV costs in the other EmERGE sites.