Threats of cross-contamination on effects of a sexual risk reduction intervention: Fact or fiction

This study sought to empirically evaluate the extent and impact of cross-contamination on the effects of a STI/HIV intervention trial previously shown to be effective in reducing high-risk sexual behaviors among African-American adolescent females. Participants were recruited through community health agencies in the Southeastern United States and comprised 522 sexually active 14- to 18- year-old African-American females who completed self-administered questionnaires and face-to-face interviews at baseline, 6- and 12-month time points. Participants were randomized to a STI/HIV risk reduction group or a general health promotion groups. The STI/HIV intervention group participated in four group sessions addressing constructs such as HIV knowledge, communication, condom use self-efficacy and condom use behaviors. The control group participated in four group sessions focused on general health topics. The study setting afforded multiple opportunities for cross-talk between intervention and control group participants. Consistent condom use, defined as condom use during every vaginal sex act, was the primary outcome measure. Other outcome measures included various sexual behaviors, observed condom application skills and psychosocial variables associated with HIV preventive behaviors. Approximately 73% of participants reported some level of cross-talk. Linear and binary GEE models assessing the impact of the STI/HIV intervention on contaminated vs. uncontaminated control group participants indicated no differential effects of the intervention. Furthermore, equivalence tests demonstrated that contaminated and uncontaminated control groups were equivalent. Findings from this study provide empirical evidence suggesting that behavioral and psychosocial outcomes may be resistant to cross-contamination in randomized controlled trials testing safer sex interventions among African-American adolescent females.