O10 Emergency department (ED) opt out BBV testing: an effective tool to diagnose the undiagnosed

<h3>Background</h3> Opt-out ED Blood borne virus (BBV) testing for HIV/HBV/HCV launched in April 2022 in EDs in areas of very high HIV diagnosed prevalence. All ED attendees over 18 years of age having blood tests done for any reason, were tested for HIV/HBV/HCV. We describe demographics and linkage to care of new hepatitis B diagnoses at a South London centre serving a diverse community in the first 18 months of testing. <h3>Methods</h3> Demographic data were collated and summarized and linkage to care and clinical parameters were collected for all new hepatitis B diagnoses at King’s College Hospital NHS Foundation Trust between November 2022 and April 2024 across 2 acute hospitals Emergency Departments. <h3>Results</h3> During the first 18 months of ED testing, 837 patients tested positive for hepatitis B or C. 715 (85.42%) were positive for hepatitis B surface antigen (HBsAg). Out of these 715; 173 (24.20%) were identified as new HBV diagnoses, 407 (56.92%) known HBV (351 in care &amp; 56 lost to follow up), 40 (5.59%) unlinked to care, 20 (2.80%) RIP, 23 (3.22%) indeterminate, 52 (7.27%) duplicates or multiple attendance. Patients with a new diagnosis of HBV are shown in table 1. So far 132 (76.30%) patients have been seen in liver outpatients - treatment was initiated in 24 patients. Two patients were found to have Hepatocellular Carcinoma. <h3>Conclusion</h3> ED testing has identified a high number of people with previously undiagnosed HBV. This represents a great increase in demand for clinical care and novel treatment pathways will be needed. To date, we have achieved good linkage to care. This testing program has unearthed an appreciable burden of disease with 30% of those who have had fibrosis assessment demonstrating at least moderate fibrosis. 14% have initiated treatment so far. Under the new WHO HBV treatment guidelines, 28% would be eligible based on APRI score. Identifying high numbers of HBV cases is a double edged sword, preventing future morbidity from HCC yet potentially placing a burden on clinical services today. Nonetheless this data demonstrates that ED opt out testing is a powerful tool to diagnose patients with HBV and should be recognised as a success story which warrants ongoing funding.