P131 Screening for HDV infection in newly diagnosed HBsAg positive patients: comparison of testing between specialist hepatology laboratory vs. community virology laboratory in South East London

Chronic hepatitis delta (HDV) represents the most severe form of chronic viral hepatitis with accelerated rates of advanced liver fibrosis and hepatocellular carcinoma, compared to HBV mono-infection patients. It is estimated that 5% of HBV infected patients are co-infected with hepatitis D virus (HDV). The true prevalence is not known, as HBsAg-positive patients are not universally screened for the presence of anti-HDV antibodies, and the data may be skewed in cohorts referred for chronic liver disease.We aimed to compare the seroprevalence of anti-HDV antibodies and HDV RNA status in two referral settings: a specialist hepatitis laboratory where testing for anti-HDV antibodies all newly diagnosed HBsAg-positive patients is universally applied vs. a community laboratory where reflex testing of all HBsAg-positive patients was similarly applied.All new HBsAg-positive patients seen in a tertiary hospital hepatology clinic (n=238) between 1.1.2021–31.12.2021 were tested for the presence of anti-HDV (ETI-AB-DELTAK-2 by DiaSorin) and all anti-HDV-positive samples were tested by a pan-genotypic in-house HDV RNA assay (LLQD=640 copies/ml). Testing in a second cohort of newly diagnosed HBsAg-positive patients from hepatology clinics was repeated between 1.1.2022–31.12.2022 (n=322). For comparison the samples from 214 HBsAg-positive patients referred from a community laboratory (i.e. a cohort identified in GP practice and non-liver clinics/wards) between 1.1.2022– 1.12.2022 had a sample sent for reflex testing to a specialist hepatitis laboratory (anti-HDV antibodies test followed by HDV RNA test in all anti-HDV-positive samples).ResultsIn 2021, out of 238 newly HBsAg-positive patients seen in hepatology clinics (tested in a specialist hepatitis laboratory) 17 (7%) were anti-HDV-positive; 9 (3.8%) had detectable HDV RNA. In 2022, out of 322 newly diagnosed HBsAg-positive hepatology patients 23 (7%) patients were anti-HDV-positive and 12 (3.7%) of these patients had detectable HDV RNA. In contrast, out of 214 HBsAg-positive patients (35 newly diagnosed) tested in the community laboratory only 5 (2.3%) were anti-HDV-positive and only one (0.5%) was HDV RNA positive. All newly diagnosed HBsAg-positive patients tested in a community laboratory including 1 (2.8%) anti-HDV-positive patient who was HDV RNA-positive were linked into hepatitis clinics care.ConclusionThe seroprevalence of anti-HDV was lower in HBsAg-positive patients tested in community laboratory setting th