Trend Analysis and Prediction of Syphilis Incidence and Mortality in China from 1992 to 2021

Background/Objectives: To analyze the incidence and mortality trend of syphilis in China from 1992 to 2021, and to evaluate the impact of age, period and birth cohort factors on the incidence and mortality of syphilis, so as to provide reference for the targeted prevention and control management of syphilis and the rational allocation of health resources. Methods: The incidence and mortality data of syphilis in China from 1992 to 2021 in the Global Burden of Disease 2021 (GBD 2021) database. were collected. The age-standardized incidence rate (ASIR) and age-standardized mortality rate (ASMR) of syphilis from 1992 to 2021 were described by the joint point regression model. The age-period-cohort (APC) model was used to analyze the effects of age, period and birth cohort factors on the incidence and mortality of syphilis. The Nordpred model was used to predict the incidence and mortality of syphilis in 2022-2046. Results: Compared with 1992, the overall incidence of syphilis in 2021 increased by 0.93%, the number of males decreased by 1.57%, and the number of females increased by 11.81%. During the same period, the overall ASIR and ASMR decreased by 0.95% and 12.50%, respectively. The ASIR of males decreased by 3.93%, and the ASIR of females increased by 10.81%. The regression analysis of the coupling points showed that the ASIR and ASMR of syphilis in China showed an upward-downward-upward trend from 1992 to 2021. The age effect of the APC model showed that the risk of syphilis in both men and women showed an inverted U-shaped curve, with peaks at 25-29 years old and 20-24 years old, respectively. The risk of death increased with age. The period effect showed that the risk of syphilis in men increased with the passage of time, while that in women increased first and then decreased with the passage of time. The risk of death for both men and women decreased over time. The birth cohort effect showed that the later the birth, the lower the risk of syphilis incidence and death. The results of Nordpred model showed that the number of syphilis cases, deaths and age-standardized rates showed a downward trend from 2022 to 2046. Conclusions: From 1992 to 2021, the overall incidence and mortality of syphilis in China showed an upward-downward-upward trend. The risk of syphilis incidence and death was affected by age, period and birth cohort factors. Young people, especially men, were the main group of syphilis incidence. The risk of syphilis death in the elderly population was high. Syphilis screening and treatment should be strengthened to reduce the risk of death.