Objective To analyze the age-period-cohort characteristics of hepatitis E incidence in the Yangtze River Delta region from 2005 to 2020, thereby providing support for the formulation of prevention and control measures.

Methods Data on the incidence of hepatitis E among individuals aged 15 and above in the Yangtze River Delta region, covering four provinces/municipality from 2005 to 2020, were obtained from the China Public Health Science Data Center. The Joinpoint regression model was employed to analyze the trend of hepatitis E incidence. The Bayesian age-period-cohort effect model was employed to analyze the age effect, period effect, and cohort effect of hepatitis E incidence.

Results From 2005 to 2020, a total of 112 348 cases of hepatitis E aged 15 and above were reported in the Yangtze River Delta region, with an average age-standardized incidence rate of 3.393 cases per 100 000 individuals. The Joinpoint regression model analysis showed that the age-standardized incidence rate of hepatitis E in the Yangtze River Delta region from 2005 to 2020 initially rose (from 2005 to 2011, with an average annual percent change of 6.419%, P < 0.05) and then declined with fluctuations. The incidence trends in Anhui province, Jiangsu province, and Zhejiang province were consistent with the overall trend, while that in Shanghai remained steady with fluctuations. Bayesian age-period-cohort model analysis showed that in terms of age effect, the hepatitis E incidence rates in different provinces/municipality of the Yangtze River Delta region exhibited a consistent upward trend among people aged 15–74 years. With the increase in age after 70–74 years old, the incidence rate continued to rise in Anhui province and Shanghai, decreased in Jiangsu province, and remained steady in Zhejiang province. The trend of disease risk from 2005 to 2011 was consistent in Jiangsu province (rising from 0.74 to 1.21), Zhejiang province (rising from 0.84 to 1.07), and Anhui province (rising from 0.61 to 1.44), all showing an upward trend, while from 2011 to 2020, the trend declined, dropping to 0.79, 0.83, and 0.69, respectively. In Shanghai, the RR values from 2005 to 2013, 2014 to 2017, and 2018 to 2020 showed a decline (from 1.22 to 0.76), an increase (rising to 1.32), and then a decline again (down to 0.89). In terms of cohort effect, the overall risk of hepatitis E in the Yangtze River Delta region showed an increasing trend in the birth cohorts from 1918 to 1960 (overall RR value rising from 0.35 to 1.66). After 1960, Jiangsu province experienced the most significant decrease (RR value dropped from 1.51 to 0.17).

Conclusion The hepatitis E incidence shows different trends among different provinces/municipality in the Yangtze River Delta region, generally exhibiting a fluctuating trend. Nevertheless, it remains necessary to strengthen health education and monitoring efforts for the elderly population aged 70–74 and above.