Effects of syndemics on HIV viral load and medication adherence in the multicentre AIDS cohort study

Objectives: The objective of this study is to determine associations between intertwining epidemics (syndemics) and HIV medication adherence and viral load levels among HIV-positive MSM and to test whether adherence mediates the relationship between syndemics and viral load. Design: We analysed participant data collected between 2003 and 2009 from the Multicenter AIDS Cohort Study, a prospective HIV/AIDS cohort study in four U.S. cities. Methods: We conducted longitudinal analyses (repeated measures mixed models) to assess whether differences in viral load levels, undetectable viral load and self-reported HIV medication adherence were associated with count of syndemic conditions (substance use, depression symptoms and sexual risk behaviour, range 0-3), adjusting for race/ethnicity, age and income. Mediation analyses were conducted using structural equation modelling and the SAS %mediate macro. Results: Syndemics count was associated with higher viral loads (P<0.0001) and lower adherence (P<0.0001). Increased counts of concomitant syndemics were associated with viral load (P<0.01), detectable viral load (P<0.05) and adherence (P<0.001). Black MSM experienced worse outcomes across domains than white MSM (P<0.0001) and experienced higher overall rates of syndemics (P<0.01). Adherence significantly mediated the relationship between syndemics and viral load, accounting for an estimated 32.3% of the effect (P<0.05). Conclusion: Effectively lowering viral load levels among MSM has implications for both HIV/AIDS prevention and care. Our findings suggest that integrating substance use interventions, mental healthcare and sexual risk prevention into standard HIV care may be necessary to optimize treatment and Treatment as Prevention (TasP) models.