Substance use patterns of HVTN phase I clinical trial participants: Enrollment, risk reduction counseling and retention.

BACKGROUND: The primary objectives of HIV Vaccine Trials Network (HVTN) phase 1 preventive HIV vaccine clinical trials are to assess safety and immune response to study products. Participant alcohol and drug use may affect adherence, retention, and risk of HIV infection. Data on the effects of substance use are limited to medical care compliance and treatment adherence in HIV infected participants. To our knowledge, there are no data assessing substance use and retention in these vaccine trials. METHODS: We performed a meta-analysis on substance use and its impact on retention in HVTN phase I trials that recruited participants demonstrating lower risk profiles for HIV infection. Our analysis included data from 10 HVTN phase 1 clinical trials conducted between February 2009 and September 2014 in the Americas and Switzerland that utilized the identical interviewer-administered behavioral risk assessment questionnaire to capture participant self-report of substance use in the previous six months. Chi Square tests were used to assess statistical differences between variables. RESULTS: Among the 964 participants, 170 (18%) missed a clinic visit and 78 (8%) terminated early from clinic follow-up; 75/774 (10%) on studies with multiple vaccination timepoints did not complete their vaccinations. Neither frequency of alcohol use, binge drinking, marijuana, nor other drug use reported at screening visits were associated with the three adherence/retention measures. Binge drinking was associated with higher rates of unprotected sex while drunk (p < .001). CONCLUSIONS: Light to moderate alcohol use does not negatively impact adherence or retention in phase I clinical trials. Based on these screening data and the low infection rate of participants during the trial period, the screening process for participation in HVTN phase 1 trials has largely been successful in enrolling and retaining individuals with lower risk profiles. Focusing on binge drinking and increased HIV/STI risk during risk reduction counseling may be warranted.