Assault related substance use as a predictor of substance use over time within a sample of recent victims of sexual assault

Substance use at time of assault is reported by a significant subgroup of rape victims. This study examined: (1) prevalence of assault related marijuana or alcohol use among women seeking post-rape medical care; (2) sensitivity, specificity, positive and negative predictive power associated with reported use at time of assault in association with use in 6 weeks pre-assault, post-assault use, and post-assault abuse; and (3) trajectories of use and abuse over time as a function of use in 6 weeks pre-assault/assault time frame use, exposure to brief intervention, and interaction of pre-assault/assault time frame use with intervention. Participants were 268 women seeking post-sexual assault medical services completing one or more follow-up assessment at: (1) <3 months post-assault; (2) 3 to 6 months post-assault; and (3) 6 months or longer post-assault. Use of alcohol or marijuana at time of assault was a fairly sensitive and specific indicator respectively, of reported use of specific substance in the 6 weeks preceding assault and use or abuse at follow-up. Growth modeling revealed that use of alcohol or marijuana at the time of the assault or in the 6 weeks prior to assault predicted higher Time 1 follow-up alcohol and marijuana use and abuse. Although there was relatively little change in use or abuse over time, alcohol use at time of the assault or in the 6 weeks prior also predicted a steeper decline in alcohol use over the course of follow-up. Interestingly, women who reported using marijuana at the time of the assault or in the 6 weeks prior who also received a video intervention actually had lower initial marijuana use, a pattern that remained stable over time. Implications for evaluating screening, brief intervention and referral to treatment services among sexual assault victims seeking post-assault medical care are discussed.