Testing a theory of syndemics in YMSM using structural equation modeling

Background: The theory of syndemics has been widely applied to studies of HIV and other health risk in young gay men. Previous applications of syndemics theory have utilized additive measurement models to create a measure of psychosocial burden, and have computed simple correlations of psychosocial problems with unprotected sex. We sought to advance the theory through the application of structural equation modeling.

Methods: Participants were actively recruited from community-based settings and the Internet for participation in a cohort study. Data from the baseline assessment were used in this analysis. Data for participant characteristics and mental health were collected via computer-assisted survey. Illicit drug use and unprotected sex behaviors for the month prior to assessment were collected via a calendar-based technique. We developed and tested structural equation models for mental health burden, drug use, and unprotected sex and also tested a second-order models for a single syndemic.

Results: First-order measurement models for each of the three epidemics were successfully fitted using the observable data. Tests of the second-order model seeking to explain the three epidemics as a single syndemic fit poorly. However, a second-order construct comprised of mental health burden and drug use fit the data well and was highly associated with the first-order construct of unprotected sex.

Conclusions: The findings advance a theory of syndemics and suggest that HIV prevention programming and counseling must be embedded in a holistic approach to care that considers unprotected sex in relation to and in sync with drug use and mental health.