Age-Period-Cohort analysis of gonorrhea surveillance data in Eastern China from 2005 to 2024

Gonorrhea poses a major public health challenge. This study analyzed the independent effects of age, period, and birth cohort on gonorrhea incidence in Eastern China to inform targeted interventions. Case data from Zhejiang Province (2005–2024) were obtained from the China Information System for Disease Control and Prevention. Age-Period-Cohort and Joinpoint regression models were used to evaluate trends and effects. A total of 347,868 gonorrhea cases were reported, with an average annual incidence of 31.87 per 100,000 and a male-to-female ratio of 3.66. Joinpoint analysis identified three distinct trends: a significant decrease during 2005–2012 (Annual Percentage Change=-10.56%; P < 0.01), followed by an increase from 2012 to 2017 (Annual Percentage Change = 5.90%; P = 0.03), and a subsequent decline from 2017 to 2024 (Annual Percentage Change=-10.24%; P < 0.01). Overall, the net drift showed an average annual decrease of 4.80%. However, local drift revealed a significant increasing incidence in the 15–19 age group (Annual Percentage Change = 4.88%). Age-effect analysis identified the highest incidence in the 20–29 age group, with a minor peak in children aged 0–4; this latter group also exhibited the most rapid decline among all age categories. Males had a consistently higher risk than females after age 15. The period effect showed the highest risk in 2005–2009 (RR = 1.62) and the lowest in 2020–2024 (RR = 0.69). Cohort effect analysis indicated that later birth cohorts had lower risks, with the highest risk in the 1920–1924 cohort (RR = 36.51) and the lowest in the 2020–2024 cohort (RR = 0.04). The overall incidence rate of gonorrhea in Zhejiang Province exhibited a downward trend, underscoring the effectiveness of existing prevention and control strategies. The period effect showed an overall declining risk over time, while the cohort effect was marked by lower incidence risk among those born in later years. In terms of the age effect, the 20–29 years age group was a high-incidence population, which should be controlled through a combination of school-based health education integrated with digital platforms and the expansion of affordable and accessible gonorrhea testing services, while also exploring novel interventions such as expedited partner therapy. Furthermore, future targeted interventions for males should include incorporating gonorrhea testing into relevant occupational health check-ups and establishing confidential sexually transmitted infection testing services.