To analyze the trends in the incidence and mortality of infectious diarrhea in China from 1990 to 2021 and predict the incidence and mortality rates for 2022 to 2026, providing evidence for surveillance and prevention strategies.

Data on the incidence and mortality of infectious diarrhea in China from 1990 to 2021 was collected from the 2021 Global Burden of Disease (GBD 2021) database. The Joinpoint regression model was used to analyze temporal trends in incidence and mortality. The age-period-cohort model was applied to explore the age, period, and cohort effects on the risk of incidence and mortality. An autoregressive integrated moving average (ARIMA) model was used to predict the incidence and mortality rates of infectious diarrhea in China from 2022 to 2026.

Joinpoint regression analysis revealed that from 1990 to 2021, the total, male, and female incidence rates of infectious diarrhea in China showed a declining trend (all P < 0.05), with a slower decrease before 2000 and a more rapid decline thereafter. Total, male, and female mortality rates also declined (all P < 0.05), with a faster decrease prior to 2014 and a slower decline after 2014. Age-period-cohort model analysis revealed that the age effects on incidence and mortality risks for the total, male, and female first decreased and then increased. The RRs of incidence decreased from high values of 2.432, 3.364, and 2.002 in the 0- < 5 age group to the lowest values of 0.478, 0.535, and 0.451 in the 25- < 30 age group. After that, it rose to peak values of 3.204, 2.523, and 3.774 in the ≥85 age group, with all P < 0.001. The RRs of mortality decreased from high values of 3.403, 3.084, and 4.312 in the 0- < 5 age group to the lowest values of 0.061, 0.063, and 0.071 in the 15- < 20 age group, and subsequently increased to peak values of 131.617, 134.317, and 133.610 in the ≥85 age group, with all P < 0.001. The period effects showed a decline trend, with both incidence and mortality RRs reaching their lowest values in 2017-2021, at 0.521, 0.582, 0.498 and 0.273, 0.283, 0.265, respectively, with all P < 0.001. The cohort effects initially increased and then decreased. The RRs of incidence rose from the lowest values of 0.254, 0.312, and 0.214 in 1907-1911 (all P < 0.001) to peak values of 1.868, 1.493, and 2.142 in 1997-2001 (P < 0.001 for the total population and females, P=0.009 for males), and then decreased to low values of 1.212, 0.873, and 1.352 in 2017-2021 (all P>0.05). The RRs of mortality increased from low values of 0.144, 0.165, and 0.143 in 1907-1911 (all P < 0.001) to peak values of 3.613, 3.265, and 3.584 in 2002-2006 (all P < 0.001), and then decreased to low values of 2.315, 2.054, and 2.313 in 2017-2021 (P=0.011 for the total population, P=0.027 for males, P=0.016 for females). Predictions from the ARIMA model suggested that from 2022 to 2026, the incidence of infectious diarrhea in China is projected to show an upward trend, while mortality is expected to continue declining.

The incidence and mortality of infectious diarrhea in China are influenced by age, period, and cohort effects. While the incidence shows an upward trend, mortality continues to decline. Children and the elderly remain high-risk populations for both onset and death. Targeted prevention strategies should be implemented to reduce the disease burden of infectious diarrhea.