Investigator: Dr. Brian Mustanski
Co-Investigators:Dr. Michelle Birkett, Dr. Noshir Contractor, Dr. Richard D’Aquila,  Dr. Michael Newcomb

Project Director:  Antonia Clifford
Funder: National Institute on Drug Abuse (NIH Grant Page)



The purpose of RADAR is to identify and understand the connections between sexually transmitted infections (STIs), substance use, and romantic relationship patterns over time among YMSM.  To achieve this, RADAR has built a longitudinal dyadic-network cohort of nearly 1200 diverse young men who have sex with men (YMSM) to understand the interplay of HIV and substance use. The project utilizes a multilevel research design that incorporates biological, dyadic, and network components to provide an unprecedented view into HIV transmission epidemiology. Cohort members are assessed every 6 months on individual behavior and risk, relationship and sexual partner characteristics, social, sexual, and drug-using network, and receive multiple biological assessments (drug and STI testing and banking of plasma and DNA). The RADAR cohort includes both HIV-positive and negative participants, and continues to build a repository of HIV sequence data and biospecimens from time points before, during, and after acute infection that will also facilitate future proposals evaluating substance use, HIV risk, pathogenicity, and immunity.

The four primary aims of this research study are:

  • Aim 1: To understand how co-occurring problems (or “syndemics”) of substance use, HIV, STIs, mental disorders and violence develop among YMSM and their partners over time.
  • Aim 2: To determine how relationship characteristics (or dyadic processes) influence HIV risk behaviors and transmission among YMSM by enrolling their serious sexual partners into the cohort. Tracing the evolution of changes in HIV characteristics will be linked to transmissions within partnerships and networks to determine what behavioral, partner and dyadic factors predict HIV transmission.
  • Aim 3: To describe network and social influences on “syndemic” development among YMSM. The examination of participants’ sexual and drug use network structures will be used to explain racial differences in rates of HIV transmission, including network size and density, interconnectedness of social networks, and the tendency for people to be connected to others who are similar to themselves.
  • Aim 4: To determine if, and how, substance use increases risk of HIV infection and the amount of HIV (or viral load) in a person’s blood. We hypothesize that substance use is associated with the risk of acquiring HIV by elevating viral loads in those already infected, and preventing the immune system of uninfected persons from working to prevent HIV transmission.

The RADAR cohort is ethnically and racially diverse (33.7% identify as Black, 29.9% identify as Hispanic, 25.3% White, 7.7% multiracial, and 3.5% other), and representative of the ethnic/racial demographics of Chicago. In the total enrolled cohort (N=1,114), HIV prevalence is 16.2% at baseline, with disparities by age and race consistent with the HIV epidemic in Chicago. Of note, 36.2% of our YTW participants are HIV-positive. Further characteristics of the cohort are discussed below.

The RADAR cohort includes participants from nearly every neighborhood in Chicago. Nearly 20% of the cohort currently resides outside of the city of Chicago, including participants in 39 states and 4 countries. 

As of January 2019, 1,115 participants have enrolled in the study. Study visits are ongoing, and the majority of the cohort has completed the 1.5 year follow up visit, with an overall retention rate of 93%. In September 2017, recruitment shifted to serious partner recruitment. Specific to the aim of collecting dyadic data, the project has successfully recruited and completed visits on 315 dyads.