Trend in the detection rate of syphilis among older adults: time series analysis, Brazil, 2014-2023

To analyze the trend in syphilis detection among older adults in Brazil from 2014 to 2023.

Analytical time-series study using data on acquired syphilis in individuals aged 60 years or older, obtained from the Notifiable Diseases Information System (Sistema de Informação de Agravos de Notificação, SINAN). Trend analysis was performed using segmented regression to calculate the Average Annual Percent Change (AAPC). Variables analyzed included sex, age group, and macroregion.

A total of 117,297 cases were reported (8.28% of total notifications). The mean detection rate was 59.80 cases per 100 thousand older adults, higher among men (77.39/100,000 versus 50.65/100,000 among women). The highest rates occurred in the 70-79-year age group (80.75/100,000), particularly in the South (114.88/100,000) and Central-West (102.68/100,000) regions. Until 2020, a significant national upward trend was observed (among women aged 70-79 years, AAPC 26.56; men aged ≥80 years, AAPC 23.71). Between 2020 and 2023, most groups showed stability, although increases persisted in subgroups, such as men aged 70-79 years in the Southeast (AAPC 20.63) and South (AAPC 16.14).

Syphilis increased significantly until 2020 and subsequently stabilized at a high plateau. Gender and regional disparities were evident: mean rates were higher among men than among women and in the South and Central-West regions than at the national average. Persistent growth after 2020 highlights a public health problem requiring targeted sexual health policies.