Estimating age-related incidence of HBsAg seroclearance in chronic hepatitis B virus infections of China by using a dynamic compartmental model

Abstract

The age-specific seroclearance pattern of hepatitis B surface antigen (HBsAg) in chronic hepatitis B virus (HBV) infections of China remains unclear. In this study, based on three national serosurvey data of hepatitis B in China, we propose an age- and time-dependent discrete model and use the method of non-linear least squares to estimate the age-specific annual rate of HBsAg seroclearance. We found that the HBsAg seroclearance in chronic HBV infections of China aged 1–59 years occurred at an average annual rate of 1.80% (95% CI, 1.54–2.06%) from 1993 to 2006. The HBsAg seroclearance occurred predominantly in the early childhood, 20–24 and 35–39 year age groups. Moreover, our model estimated that HBsAg seroclearance resulted in 23.38% of the decrease of total HBsAg prevalence for population aged 1–59 years in 2006. It also prevented 9.30% of new HBV infections (about 7.43 million people) and 9.95% of HBV-related deaths (about 0.25 million people) from 1993 to 2006. This study develops a new and efficient method to estimate the age-specific incidence of HBsAg seroclearance at a population-level and evaluate its effect.

Estimating the impact of test-and-treat strategies on hepatitis B virus infection in China by using an age-structured mathematical model

“…We compared the estimated age-specific HBsAg prevalence by model with national survey data in 2006 and 2014. [ 6 – 8 , 32 , 33 ] Compared with the national survey data in 2006, [ 6 ] we can see that the estimated values from our model fitted very well with survey data in 2006 and the maximum absolute error was 0.0028. All estimated values fell into the 95% confidence intervals of observed values (Supplementary Fig.…”

“…2B). [ 7 , 8 , 32 , 33 ] This comparison analysis demonstrated that our model and estimated parameters were credible and can be used to predict the prevalence of HBsAg in the future.…”

“…According to the natural history of HBV infection and main features of HBV transmission in China, we constructed a dynamic compartmental model of HBV transmission. [ 8 , 19 – 23 ] In this model, the total population was divided into 3 compartments: susceptible to HBV infection S a ( t ); chronic HBV carriers C a ( t ); recovered and obtained immunity due to HBV infection or vaccination R a ( t ); where a represented age and t represented time. We took “year” as a basic unit of time.…”

“…[ 5 , 6 ] A recent national serosurvey of hepatitis B in China revealed that the hepatitis B surface antigen (HBsAg) prevalence for population aged 1 to 29 years was 2.6% in 2014. [ 7 , 8 ] Based on these surveys, it was estimated that in 2014, there were more than 71 million people with chronic HBV infection in China, about 28 million people were patients with chronic hepatitis B disease (defined as someone who has chronic hepatitis disease due to chronic HBV infection), and approximately 25% to 40% of these chronic HBV carriers (defined as someone who carries HBsAg for >6 months) would develop into cirrhosis and hepatocellular carcinoma (HCC). [ 2 – 10 ] Hepatitis B virus had become the primary cause of mortality in China.…”

“…The objective of this study was to develop a dynamic compartmental model of HBV transmission to estimate the impact of increasing test-and-treat coverage on HBV infection in China. Overall, based on 3 national survey data of hepatitis B in 1992, 2006, and 2014, [ 5 – 8 ] we predicted the number of new HBV infection, the number of chronic HBV infection, and the number of HBV-related deaths in China for the time from 2018 to 2050 under 5 different test-and-treat coverage and compared them with the current intervention policy.…”