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.