Is there a need for universal double reflex testing of HBsAg-positive individuals for hepatitis D infection?

Hepatitis D virus (HDV) can infect HBsAg-positive individuals, causing rapid fibrosis progression, early decompensation, increased hepatocellular carcinoma risk, and higher mortality than hepatitis B virus (HBV) mono-infection. Most countries lack high-quality HDV prevalence data, and the collection techniques employed often bias published data. In recent meta-analyses, HDV prevalence in HBsAg-positive patients reaches 5%-15% and is even significantly higher in endemic areas. Since HBV vaccination programs were implemented, HDV prevalence has decreased among younger populations. However, owing to immigrant influx, it has increased in some Western countries. The current practice of HDV screening in HBsAg-positive individuals is stepwise, based on physician's discretion, and limited to at-risk populations and may require numerous visits. Double reflex testing, which includes anti-HDV testing in all HBsAg-positive individuals and then HDV RNA testing for anti-HDV-positive ones, is uncommon. Reflex testing can identify more HDV infection cases and link identified patients to further care and follow-up. Moreover, laboratory-based double reflex screening is less biased than physician-led testing. Therefore, healthcare providers should learn about reflex testing, and federal and provincial hepatitis control programs should implement laboratory-based double reflex testing to obtain reliable HDV prevalence estimates. The test's cost-effectiveness depends on the number of HBV-positive patients screened to identify one HDV-positive patient. Such testing may be viable in areas with low HBsAg but high HDV prevalence. However, its economic impact on areas with low HDV prevalence needs further study.