Background Syndemics theory proposes that diseases may cluster and intensify based on multiple interacting factors. Few studies have compared methods to identify syndemics related to sexually transmitted infection (STI) risk. The purpose of this study is to compare the use of a composite scoring method and latent class analysis to identify syndemics of STI risk.

Methods Youth were aged 18–25 who participated in the National Health and Nutrition Examination Survey, 2011–2014 (N=1,803). Syndemic composite scoring was tabulated by an accumulation of indicators by gender, and latent class analysis (LCA) was conducted to extract classes of risk based on indicators reported by gender. The outcome, STIs, was defined as a determinant result for Chlamydia trachomatis, Herpes Simplex Virus type-2, or HIV. The odds of STI were calculated using the patterns of risk by sex adjusted for demographic and poverty indicators.

Results Composite score results suggest that males with an accumulation of 3 to 5 syndemic indicators (AOR: 2.10 CI 95% 1.0–4.2) and 6 or more indicators (AOR: 2.84 CI 95% 1.2–6.7) had an increased odds of STI. Similarly, females with 6 or more indicators (AOR: 3.20 CI 95% 1.7–6.0) had increased odds of STI. The LCA suggested that men with the highest probability of smoking and sexual risk behaviors were at increased odds of STI (AOR: 2.42 CI 95% 1.1–5.4), while women exhibit a syndemic of depression, smoking, drug use and sexual risk behaviors (AOR: 2.19 CI 95% 1.2–3.8).

Conclusion The co-occurrence of mental health,substance use and smoking were important indicators of STI risk in women. LCA was able to determine indicators that co-occurred in men and women and sexual risk behaviors that differed by gender, while the syndemic scoring show an accumulation of indicators increased STI risk.

Disclosure No significant relationships.