[Study of hepatitis B virus replication and infection by other hepatitis viruses in patients with chronic hepatitis B virus infection]

Update on epidemiology of hepatitis B in a low-endemic European country: There is still much to do

The latest epidemiological data in Spain were obtained a decade ago and revealed a prevalence of hepatitis B surface antigen (HBsAg) of 0.7%; hence, updated epidemiological data are necessary. Our aim was to determine the prevalence of hepatitis B virus (HBV) infection, and to analyse associated factors and characterize chronic infection. A population-based, cross-sectional study was performed in Spain between July 2015 and April 2017. Participants from three regions were selected using two-stage conglomerate sampling and stratified by age. Anthropometric and demographic data were collected, and blood samples were taken to detect serological markers of HBV infection and to quantify HBV-DNA. The characterization of chronic HBV infection was based on ALT (alanine aminotransferase) values, HBV-DNA levels, and results of transient elastography. The overall prevalence rates of HBsAg and antibody to hepatitis B core antigen (anti-HBc) among 12 246 participants aged 20-74 years (58.4% females) were 0.6% (95% CI [0.4-0.7]) and 8.2% (7.7-8.7), respectively. The risk factors for HBV infection identified in the multivariate analysis were age, nosocomial risk, and non-Spanish nationality. Moreover, most patients HBsAg positive (76.6%) presented as hepatitis B e antigen (HBeAg)-negative chronic infection (formerly 'inactive carriers') and only 6 (9.4%) HBsAg carriers fulfilled current criteria for treatment. The current HBV burden in Spain remains low but virtually unchanged over the past 15 years. Increased efforts are still needed to reach the goal set forth by the World Health Organization (WHO) for HBV elimination by 2030.

Estimating the future health burden of chronic hepatitis B and the impact of therapy in Spain

BACKGROUND

Chronic hepatitis B virus (HBV) infection can lead to fatal complications and death. Only a relatively small proportion of patients actually receive medication, and the majority requires long-term antiviral therapy that can result in the emergence of resistant strains of HBV. The study aimed to estimate the future burden of chronic hepatitis B in Spain over the next 20 years, the impact of current lamivudine treatment and the emergence of drug-resistant HBV.

METHODS

We constructed a hypothetical cohort of people with active chronic HBV infection in Spain in 2005, and 'followed' the cohort for 20 years. The cohort was stratified with respect to factors that affect prognosis (i.e. hepatitis B e-antigen and histology-defined status). To estimate the burden, Markov mathematical simulation was performed based on three scenarios: natural history, treatment with antiviral drug (lamivudine) and treatment with a hypothetical drug with identical profiles to lamivudine but to which there is no resistance.

RESULTS

We estimated that in 2005 there were around 111,000 individuals suffering from active chronic HBV infection. If the cohort is not treated, by the year 2025 there will be about 60,000 events of morbidity and 40,000 cases of liver-related deaths, with 1.84 billion euro expected to be consumed in providing care for the cohort. Treating 35% of the cohort with lamivudine will reduce the morbidity and mortality by 19 and 15%, respectively; whereas the hypothetical drug will reduce the morbidity and mortality by 27 and 24%. The cumulative cost savings resulting from the use of lamivudine and the hypothetical drug, respectively, are 160 and 300 million euro. Antiviral resistance accounts for a reduction of about one-third in the potential benefit of treatment, and almost a half of the potential cost saving.

CONCLUSION

Chronic hepatitis B will pose a great burden in the future if the individuals with active disease are left untreated. Effective antiviral therapy and treatment coverage have substantial impact in reducing the future burden; however, antiviral resistance decreases treatment benefit considerably.