Joinpoint regression and age-period-cohort analyses of global and Chinese acute hepatitis C incidence trends, 1990–2021

Objective This study aimed to analyse the temporal trends of acute hepatitis C incidence and the independent effects of age, time period, and birth cohort (age–period–cohort effects) from 1990 to 2021 globally and in China. Methods Data were obtained from the Global Burden of Disease Study 2021. Joinpoint regression was used to analyse the trends in age-standardized incidence rates (ASIRs). The age–period–cohort model was employed to disentangle the underlying effects of population ageing, temporal changes, and birth cohort risks. Results From 1990 to 2021, the global ASIR of acute hepatitis C exhibited an overall declining trend (average annual percent change [AAPC] = −0.38%). However, this trend reversed after 2015, indicating a concerning resurgence. Disparities were pronounced across socio-demographic index (SDI) levels: Low-SDI regions faced the highest burden, while the ASIR in China declined most rapidly (AAPC = −1.55%). The age–period–cohort analysis revealed a bimodal age pattern, with peaks in early childhood (0–4 years) and old age (≥95 years), indicating distinct transmission routes and historical cohort risks. Conclusion Despite a long-term decline, the global increase in acute hepatitis C incidence underscores an ongoing public health challenge. Our findings highlight the urgent need to strengthen prevention and screening strategies, particularly in low-SDI regions, among vulnerable age groups, and for high-risk populations in order to achieve the goal of hepatitis C elimination.