Rising incidence of hospital-reported drug-facilitated sexual assault in a large urban community in Canada. Retrospective population-based study.

BACKGROUND Drug-facilitated sexual assault (DFSA) occurs when an individual has been sexually assaulted due to the surreptitious administration of drug(s) thereby rendering her/him unable to give consent. Our study aim was to calculate the age- and sex-specific annual incidence of hospital-reported DFSA and to determine whether a one-year increase in DFSA observed in 1999 in a pilot study on the same population was a significant and sustained trend. METHODS We identified cases of DFSA by reviewing the sexual assault examination records of all the individuals who presented to a hospital-based sexual assault care referral service in Vancouver, British Columbia during the study time period (January 1, 1993 to May 31, 2002). The annual sex- and age-specific incidence and temporal trends of drug-facilitated sexual assault were examined using population data from the British Columbia Ministry of Health. RESULTS The mean annual incidence of female DFSA increased from 3.4 per 100,000 (years 1993--1998) to 10.7 per 100,000 (years 1999--2002). Age-adjusted relative risks for female DFSAs were significantly higher in 1999 (2.77, 95% CI 1.85-4.15), 2000 (3.01, 95% CI 1.97-4.57), 2001 (3.14, 95% CI 2.07-4.78) and 2002 (4.88, 95% CI 2.84-8.37) compared to 1993-1998. Women aged 15-19 years had the highest DFSA incidence, with a year-adjusted relative risk of 3.89 (95% CI 2.75-5.50) compared to all other age groups. CONCLUSION This study demonstrates that the incidence of hospital-reported DFSA has shown a marked and sustained increase since 1999. Young women in their teens are particularly vulnerable to this form of sexual assault and further efforts are needed to develop and evaluate prevention programs for this group.