Comparison of sexual assaults by strangers versus known assailants in a community-based population.

The medical literature has generally supported the view that sexual assaults by strangers are more serious and more violent than assaults by people known to the victims. This retrospective study was conducted to compare characteristics of sexual assaults by strangers and those by people known to the victims in a community-based population of women. Study patients were consecutive female patients, age 13 years or older, presenting to a sexual assault clinic during a 40-month study period. The clinic is associated with a university-affiliated emergency medicine residency program and is staffed by forensic nurses trained to perform medical-legal examinations using colposcopy with nuclear staining. Case files of 849 patients were reviewed; the age range was 13 to 82 years (mean, 22.5 years). Sexual assault by a person known to the victim accounted for 646 (76%) cases. The majority of these assailants (68%) were described as acquaintances; 139 (21%) were current or previous boyfriends or spouses; 33 (5%) involved other family members. Sexual assault by a stranger was more likely to occur in the home of the victim (43% v 28%, P < .001), involve weapons or physical coercion (58% v 31%, P < .001), and was associated with more non-genital injuries (61% v 40%, P < .001). However, the overall frequency of anogenital trauma (77% v 71%, P = .10), the mean number of anogenital injuries (2.0 v 2.3, P = .05), and the types of genital trauma were similar in both groups of women. These results demonstrated that 71% of the victims of acquaintance rape sustain anogenital trauma and that these injuries may be as extensive as those caused by unknown assailants.