Trends and projections of the syphilis burden in China: an analysis of GBD 2021 data and global comparison

Objectives China accounts for a significant proportion of the global burden of syphilis, yet detailed comparisons of long-term epidemiological trends between China and the global population at present remain lacking. Methods Data on syphilis for China and the global population from 1990 to 2021 were extracted from the Global Burden of Disease (GBD) Study 2021. Joinpoint regression analysis was employed to identify the temporal trend. Age and sex distributions were examined, and mortality and DALY rate attributable to unsafe sex were analyzed. The future syphilis burden from 2022 to 2041 was estimated using the Nordpred model, and alternative model-based scenario analysis was conducted using complementary ARIMA and Holt-Winters models. Results Between 1990 and 2021, the number of incident cases and prevalent cases of syphilis increased by 3.64% and 12.87% in China, respectively, whereas deaths and DALYs declined by 55.75% and 55.65%, respectively. China’s age-standardized incidence rates (ASIR), age-standardized prevalence rates (ASPR), age-standardized mortality rates (ASMR), and age-standardized disability-adjusted life-year rates (ASDR) remained substantially below global levels over the 32-year period. Joinpoint analysis revealed that China’s ASMR and ASDR increased sharply during 2019–2021, with APCs of 20.75% and 20.36%, far exceeding the corresponding global values (4.43% and 4.54%). Across China and globally, ASMR and ASDR reached their highest levels among children under five, while unsafe sex-linked syphilis mortality was greatest among those aged 80 and above. Nordpred projects continued decline in China’s ASIR, ASPR, and ASDR for syphilis through 2041. In contrast, both the ARIMA and Holt-Winters models forecast upward trends in ASIR, ASPR, and ASDR. Conclusion Syphilis-related ASMR and ASDR increased during 2019–2021, a period coinciding with the COVID-19 pandemic and the final evaluation year of the National Syphilis Prevention and Control Plan. This observation warrants further investigation into the potential contributions of healthcare disruptions, surveillance artifacts, and changes in reporting practices. Strengthening prenatal syphilis screening and timely, evidence-based treatment is essential to prevent congenital syphilis; concurrently, enhancing clinicians’ diagnostic proficiency for complications associated with late-stage syphilis is critically important.