We read with interest the study by Shan et al. [1], which reviewed an integrated approach to chronic hepatitis B virus (HBV) control in China. The study indicated that HBV infection is highly endemic in China. Although the implementation of integrated strategies, including measures such as universal infant hepatitis B vaccination, has led to a significant decline in HBsAg infection in China over the past 30 years, the country still faces a huge challenge in achieving the goal of reducing HBV-related mortality by 65% by 2030 due to low diagnosis and treatment rates. Additional studies have shown that increased vaccination coverage and increasing availability of highly effective nucleos(t)ide analogs have contributed to a gradual decline of HBV-related liver cancer, but multiple disparities remain, with women and certain races/ethnicities less likely to receive antiviral therapy [2-4]. Therefore, in such a global context, quantifying cross-national inequalities associated with the current burden of HBV is critical for adapting or strengthening future strategies.

We extracted disability-adjusted life years (DALYs) data on the total burden related to HBV for 204 countries and territories from the Global Burden of Disease (GBD) Study 2021. The sociodemographic index (SDI) is a composite measure of development developed by GBD researchers and consists of 3 indicators: per capita income with lagged distribution, total fertility rate under the age of 25 years, and mean education for those aged 15 years and older [5]. It has been proven to reflect the strong association between socioeconomic development and public health. The unequal distribution of the burden of HBV across countries is measured by the health inequality slope index and the health inequality concentration index, which are standard indicators of absolute and relative gradient inequality, respectively [6]. The slope index value of inequality was calculated by regressing national DALYs rates because of the burden of HBV on an SDI-associated relative position scale, which was defined by the midpoint of the cumulative range of population ranked using the SDI. Heteroskedasticity was taken into account by using a weighted regression model. The health inequality concentration index value was calculated by numerically integrating the area under the Lorenz concentration curve, which was fitted using the cumulative fraction of DALYs and the cumulative relative distribution of the population ranked using the SDI [7].

Across the 204 countries analyzed, significant absolute and relative SDI-related inequalities in HBV were observed, with a disproportionately high burden borne by countries with lower SDI. A significant reduction in these inequalities occurred over time. As shown by the slope index of inequality, the gap in DALY rate between countries with the highest and lowest SDI decreased from –401.7 (95% confidence interval [95% CI] –470.9 to –332.4) in 1990 to –275.5 (95% CI –325.9 to –225.1) in 2021 (Fig. 1A). In addition, the concentration index value was –0.16 (95% CI –0.21 to –0.11) in 1990 and –0.06 (95% CI –0.1 to –0.02) in 2021 (Fig. 1B), suggesting a disproportionate concentration of the burden in lessaffluent countries.

The negative inequality slope index shows that the DALYs for the burden of HBV decline as the relative ranking of the SDI rises, further illustrating the fact that the overall burden of disease is concentrated in poor countries. Declines in the absolute values of these two indicators suggest a reduction in inequality in the burden of disease from 1990 to 2021, signalling a narrowing of the gap between high-income and low-income countries. While it is reassuring to see such results, the pervasive severity of the global HBV burden persists. In 2021, HBV accounted for 38% of liver cancer deaths, highlighting the enormous burden that HBV-associated liver cancers continue to place on the global health care system [8]. In addition, according to World Health Organisation estimates, at the end of 2022, only 1.9% of people with hepatitis B were receiving antiviral treatment [9]. Therefore, distributing healthcare resources based on the extent of burden inequality and maintaining or even strengthening existing trends is the goal of future public health policy formulation.