Identifying Syndemics for Sexually Transmitted Infections Among Young Adults in the United States: A Latent Class Analysis

Syndemic theory suggests that the convergence of social, environmental, and ecological factors can interact to exacerbate behavioral health problems and are often intensified by social conditions and disparities. This study used latent class analysis (LCA) to determine gender and racial/ethnic specific classes for sexually transmitted infection (STI) risk. LCA included 18 measured socioeconomic, depression, substance use, and sexual behavioral variables from 1,664 young adults ages 18–25 in the NHANES. Models were stratified by gender and then by race/ethnicity. Logistic regression determined associations between latent class membership and testing positive for one or more STIs (Chlamydia trachomatis, HIV or herpes simplex virus-II). For each stratified analysis, classes with the lowest probability of reported risk factors in the LCA were the reference groups. Class 3 in females (highest probability of reporting both socioeconomic and behavioral factors) and class 3 in males (majority behavioral factors) had increased odds of STI (females: OR = 2.7, 95% CI 1.6–4.5; males: OR 2.5, 95% CI 1.3–4.6). By race for females, depression (highest in Hispanics), poverty, and less educated households (highest in blacks and Hispanics) were evident in classes associated with STI. Class 1 black males (majority behavioral factors) had a higher odds of STI compared with low risk white males (OR = 16.4 95% CI 3.7–72.0) However, no other associations were observed among males. Risk patterns for STI differed by gender and race/ethnicity. Consistent with syndemic theory, effective STI interventions need to address socioeconomic factors and mental health rather than individual behaviors, particularly for minority women.