Adjusted estimate of the prevalence of hepatitis delta virus in 25 countries and territories

Background and Aims Hepatitis delta virus (HDV) is a satellite RNA virus that requires the hepatitis B virus (HBV) for assembly and propagation. Individuals infected with HDV progress to advanced liver disease faster than HBV mono-infected individuals. Recent studies have estimated the global prevalence of anti-HDV antibodies among the HBV-infected population to be 5-15%. This study aimed to better understand HDV prevalence at the population level in 25 countries/territories. Methods We conducted a literature review for anti-HDV and HDV-RNA-positive prevalence in HBsAg positive individuals in 25 countries/territories. Virtual meetings were held with experts from each setting to discuss the findings and collect unpublished data. Data were weighted for patient segments and regional heterogeneity to estimate the prevalence in the HBV-infected population. The findings were then combined with The Polaris Observatory HBV data to estimate the anti-HDV & HDV-RNA prevalence in each country/territory at the population level. Results After adjusting for geographical distribution, disease stage and special populations, the anti-HDV prevalence among the HBsAg+ population changed from the literature estimate in 19 countries. The highest anti-HDV prevalence was 60.1% in Mongolia. Once adjusted for the HBsAg+ population and HDV-RNA+, China had the highest absolute number of HDV-RNA+ cases. Conclusions We found substantially lower HDV prevalence than previously reported, as prior meta-analyses primarily focused on studies conducted in groups/regions that have a higher probability of HBV infection: tertiary care centers, specific risk groups or geographical regions. There is large uncertainty in HDV prevalence. The implementation of reflex testing would improve estimates, while also allowing earlier linkage to care for HDV-RNA-positive individuals. The logistical and economic burden of reflex testing on the health system would be limited, as it would only screen HBsAg+ cases. Impact and implications There is a great deal of uncertainty surrounding the prevalence of HDV among people living with HBV at the population level. This study aimed to better understand the burden in 25 countries and territories, to refine techniques that can be used in future analyses. We found a lower prevalence in the majority of places studied than had been previously reported. These data can help inform policy makers on the need to screen people living with HBV to find those coinfected with HDV and at high risk for progression, while also highlighting the pitfalls that other researchers have often fallen into.