Screening Impact of Anti-HDV Reflex Testing Among HBsAg-Positive Individuals

Background: Hepatitis D virus (HDV) causes one of the most severe forms of chronic viral hepatitis. Despite its severity, universal screening of hepatitis B surface antigen (HBsAg)-positive individuals, as recommended by European guidelines, is not widely implemented. This study aimed to evaluate the yield of reflex HDV testing and to characterize HBV carriers who tested positive or negative for anti-HDV. Methods: A retrospective cohort study was conducted using the Clalit Health Services database in northern Israel (2014-2024). HBsAg-positive patients were categorized into two groups: those screened for HDV via reflex testing (2019-2024) and those tested based on clinical discretion (2014-2019). We compared these cohorts to evaluate the impact of reflex screening on coverage, diagnostic yield, and time to diagnosis. Results: Among 1336 HBsAg-positive individuals, HDV screening rates increased from 57.5% to 93.1% following reflex implementation. HDV seropositivity increased from 3.17% to 6.48% (p = 0.02). Ethiopian-born individuals had significantly higher positivity than others (10.4% vs. 3.9%, p = 0.0221). The average time from HBV diagnosis to HDV testing decreased from 38.1 ± 31 months (median 37.5) to 1.3 ± 6.1 months (median 0). Conclusions: Anti-HDV reflex testing significantly improved screening coverage, increased detection of anti-HDV seropositive cases and was associated with shorter time to serologic identification. These findings support the integration of reflex testing into national screening policies to enable earlier diagnosis and reduce the burden of infection.