Efficacy of a behavioral intervention for increasing safer sex behaviors in HIV-negative, heterosexual methamphetamine users: Results from the fast-lane study

BACKGROUND: The risk of acquiring HIV is particularly high among persons who use methamphetamine, which is often associated with unprotected sex and high numbers of sexual partners. PURPOSE: This study examined the efficacy of a behavioral intervention emphasizing motivational interviewing and social cognitive theory for increasing safer sex behaviors in the context of ongoing methamphetamine use in a sample of HIV-negative, heterosexual methamphetamine users. METHODS: Four hundred fifty-one participants from San Diego, California, were randomly assigned to receive one of three treatment conditions: (a) a safer sex behavioral intervention (Fast-Lane [FL]), (b) the FL intervention with boosters (FL + B), or (c) a time-equivalent diet-and-exercise attention-control (D&E) condition. Random effects regression analyses were used to evaluate change in safer sex behaviors over an 18-month period. RESULTS: Compared to those in the D&E condition, participants in the FL + B condition (p = .019) and FL condition (p = .020) significantly increased their engagement in protected sex acts over the active intervention phase. Also, compared to the D&E condition, those in the FL condition demonstrated a significant decrease in unprotected sex (p = .005) and an increase in percent protected sex (p = .001) during the active intervention. Finally, relative to D&E participants, FL participants demonstrated significant improvements in self-efficacy for negotiating safer sex (p = .011), and change in self-efficacy mediated the efficacy of the FL condition for increasing safer sex behaviors (p = .033). CONCLUSIONS: These results suggest that our behavioral intervention was successful in terms of reducing high-risk sexual behaviors in the context of ongoing methamphetamine use among HIV-negative heterosexuals. Reductions in high-risk sexual behavior were likely because of the impact of the intervention on participants' self-efficacy for negotiating safer sex.