Background: The potential for behavioral disinhibition is a concern with post-exposure prophylaxis (PEP) following sexual exposures. In prior work, PEP plus enhanced (5 session) risk reduction counseling did not result in increased risk behavior. Such counseling, however, is expensive and not superior to standard (2 session) counseling in other settings. Thus, we hypothesized that 2 counseling sessions are not inferior to 5 sessions in the context of PEP.

Methods: Persons treated with PEP following sexual exposure were randomized to standard (2 session) vs enhanced (5 session) counseling. The groups were compared for differences in: a) change in no. of unprotected sex acts 6 to 12 months post-PEP compared to 6 months pre-PEP; b) 12 month incidence of further PEP use (re-PEP); and c) 12 month incidence of HIV acquisition. Non-inferiority analyses estimated one-sided 95% CIs to determine the greatest (“worst case”) differences between groups.

Results: 457 subjects were randomized to standard (STND; n=229) or enhanced (ENH; n=228) counseling. Median age was 34, 96% were men, 71% were white, and 72% were insured. Overall, there was a reduction at 12 months in the number of unprotected sex acts compared to baseline (mean 1.8 and 2.3 fewer acts in the STND and ENH groups respectively). This differed by the degree of baseline risk: among those with < 4 baseline acts, the ENH group had a slight increase (mean +1.6 acts) compared to the STND group. Among those with > 4 baseline acts, the ENH group had a mean of 6.2 fewer acts than the STND group. Differences in re-PEP and HIV acquisition followed the same pattern: those with < 4 baseline acts had little difference between counseling groups, while those with > 4 acts had important differences.

Conclusion: In persons with lower baseline risk who seek PEP following sexual exposures, standard counseling is not inferior with respect to reducing subsequent risk behavior. However, among those with higher baseline risk, standard and enhanced counseling are not equivalent. Enhanced counseling should be targeted to individuals who report higher baseline risk.