Enrollment of adolescents aged 16-17 years old in microbicide trials: an evidence-based approach

Abstract

Purpose: This article explores the ethics and feasibility of enrolling adolescent females in microbicide trials using data from 16- to 17-year-old participants of the Phase 3 trial of the candidate vaginal microbicide, Carraguard.

Methods: Secondary analysis was conducted to compare health, behavioral, and operational outcomes between 16- to 17-year-olds and 18- to 19-year-olds screened for and enrolled in the trial. Analytical approaches included Kaplan-Meier survival analysis, Cox proportional hazards modeling, and generalized estimating equations for nonsurvival end points.

Results: Results reveal no significant differences between the two age groups for health (sexually transmitted infection, adverse event), risk behavior, or operational (adherence, follow-up) outcomes. However, data suggest that after 1 year of trial participation, human immunodeficiency virus (HIV) and pregnancy incidence were higher and increased more rapidly for the 16- to 17-year-olds than for 18- to 19-year-olds; this finding is entirely consistent with other incidence data for HIV infection among South African youth and cannot be attributed to study participation without a comparison outside the trial.

Conclusions: Data from the Carraguard trial provide no evidence that inclusion of 16- to 17-year-olds in the trial had any detrimental effect on trial participants or on the conduct of research. These data provide an argument motivating the inclusion of sexually active adolescents aged 16-17 years into future trials in order to avoid delaying access to an effective product for adolescents at high risk of HIV acquisition. Careful support for adolescent-inclusive protocols (including appropriate counseling) must be incorporated into study design.

Keywords: Adolescents; Carraguard; Clinical trial design; HIV prevention; Microbicides; South Africa.