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Trends in the incidence of syphilis among US adults since 2019

by | Apr 8, 2024 | Research

Using timely, de-identified EHR data, Truveta Research explored the monthly trends in the incidence of syphilis among US adults from January 2019 to December 2023.
  • Truveta Research explored the monthly trends in the incidence of syphilis among US adults from January 2019 to December 2023. During the early months of the COVID-19 pandemic, the rate of syphilis incidence (e.g., new infection) increased significantly, reaching a peak in November 2022. By December 2023, syphilis rates returned to pre-pandemic levels.
  • The recent decline was primarily driven by individuals commonly considered high-risk for syphilis infection – including men, younger adults, Black and Hispanic individuals, and those with evidence of high-risk sexual activities, Pre-Exposure Prophylaxis (PrEP) use, or HIV/AIDS.
  • The study highlights a rise in the incidence of syphilis among groups typically considered low risk, such as women, people of white race, and those without evidence of high-risk sexual behaviors, PrEP use, or HIV/AIDs.
Syphilis is a preventable and curable sexually transmitted infection (STI). Left untreated, syphilis is associated with life-threatening complications – including brain damage, deafness, blindness, fetal death, and an increased risk of acquiring other sexually transmitted infections (STIs).

The US Centers for Disease Control (CDC) has suggested that in 2022 the number of cases of syphilis infections reached its highest level since the 1950s, raising concerns about the transmission of this STI and the potential outcomes of untreated infections.

To contribute to public health information about the most recent transmission rates of syphilis, Truveta Research explored the monthly trends in the incidence of syphilis among US adults from January 2019 to December 2023. Below is a summary of the study findings, and the full study – including full demographics, methodology, detailed findings, and more – is available on MedRxiv.

Methods

Using a subset of Truveta Data, which includes de-identified electronic health records, Truveta Research calculated the monthly incidence of syphilis using diagnostic codes and positive lab results.

In addition to capturing basic demographic details about the included population, the study also included syphilis risk factors such as whether a patient engaged in high-risk sexual activities, used PrEP, or had HIV/AIDS within the previous year.

Results

Between January 2019 and May 2020, the incidence of syphilis declined from 2.4 to 1.4 per 100,000 patients, then rapidly grew until reaching its peak level of 3.2 in November 2022. It then dropped to 2.5 in December 2023.

For all age groups, the incidence of syphilis infections increased from 2020 to 2022 then declined in 2023, with younger adults experiencing a higher incidence rate during this time. Overall, from 2019 to 2023 the trend in the rate of syphilis incidence was relatively flat for men, while it increased more than two-fold for women.

When stratifying the population by race, Black individuals had the highest incidence rate of syphilis at any time during the study period, and white and Asian individuals had the lowest. However, when looking at trends in the syphilis incidence over the five-year period, the fastest increase over time was seen in those with white or other races. When stratifying by ethnicity, Hispanic adults had a higher level and increasing trend of syphilis infections compared with non-Hispanic patients, although the rate started to decline in 2023.

Syphilis trends increased rapidly in 2019-2023 for those in the South and West regions of the US, while it declined for those in the Midwest.

Using timely, de-identified EHR data, Truveta Research explored the monthly trends in the incidence of syphilis among US adults from January 2019 to December 2023.
Levels and trends in the incidence of syphilis also differed by risk factors. The incidence of syphilis infections increased over time for those who are considered relatively low-risk for infection – those patients without evidence of high-risk sexual activities, PrEP use, or HIV/AIDS.

The recent decline in 2023 in the incidence of syphilis was primarily driven by individuals commonly considered high-risk for syphilis infection – including men, younger adults, Black and Hispanic individuals, and those with evidence of high-risk sexual activities, PrEP use, or HIV/AIDS.

Using timely, de-identified EHR data, Truveta Research explored the monthly trends in the incidence of syphilis among US adults from January 2019 to December 2023.
The full study findings can be found on MedRxiv.

Truveta Research will continue to monitor these and other public health trends.