A recent study of the forensic evidence in 563 sexual assault cases in Massachusetts found “striking similarities” in the types of injuries and violence experienced by adult and adolescent victims.

The similarities suggest that teens are at greater risk of violence and injury during sexual assaults than previously thought, according to the study’s authors, University of Illinois senior research specialist in social work Theodore P. Cross and University of Illinois College of Medicine at Urbana-Champaign alumnus Dr. Thaddeus Schmitt.

The majority of the victims were assaulted by a person they knew, such as a friend or acquaintance. Sexual assaults by strangers were less common, occurring in 18% of cases involving 12 to 15-year-old victims and nearly 31% of cases with adult victims age 18 and older, according to the study.

Likewise, adolescent victims experienced penetration and were assaulted using force, a weapon or bodily restraint at rates comparable to adult victims, the researchers found.

In examining police records, the researchers found that arrests were about twice as likely when victims were under the age of consent, occurring in 52% of all cases involving victims under age 12.

However, arrests were made in just 25% of the cases involving 16 to 17-year-old victims and in 24% of the cases involving adult victims, the researchers found.

While prior studies found greater differences in the rates of violence experienced by adults and adolescents, Cross said “our study may be more generalizable to cases as a whole because the sample was derived from a statewide array of hospitals rather than from a single hospital or specialized center.”

Cross and Schmitt compared forensic medical results and law enforcement actions in sexual assault cases that occurred in Massachusetts from 2008-10.

They pulled a random sample of cases from a statewide database of medical reports on sexual assault examinations conducted in hospital emergency departments, looking at data from crime laboratory reports, police records and sexual assault evidence collection kit forms.

The final sample in the study included 33 cases in which the victims were under age 12. There were 66 cases with victims in the 12-15 age group, 48 cases involving 16 to 17-year-old victims, and 416 cases with adult victims.

Biological evidence such as sperm/semen, blood and saliva, and DNA was found at similar rates among adults and adolescents but was significantly less likely to be found on children under age 12. Across all age groups, obtaining a DNA match to the alleged suspect, to a suspect in another case or to a convicted offender was uncommon, the researchers found.

“Although previous studies suggested that obtaining biological evidence that could be matched to DNA profiles is greatest among adult victims, less common with adolescents and substantially less likely among children, we found no meaningful differences, nor was the rate of DNA matches to the suspect different,” Cross said.

“It is surprising that the rate of DNA profiles and matches was not substantially less for children than older victims, given that finding biological products was less likely among child victims,” he said.

The researchers also found that use of force and choking the victim significantly increased with the age of the victim.

About half of the adults received nongenital injuries, compared with 27% of children under age 12. Likewise, adolescents received nongenital and anogenital injuries at similar rates to adults, a finding that conflicted with most prior studies, according to the researchers.

“Almost half of younger adolescents were reported to have a nongenital injury and over one third had an anogenital injury,” Schmitt said. “These results should heighten concern about the trauma that even young adolescent victims experience.”

Schmitt said little research has focused on sexual abuse and sexual assault among adolescents; therefore, the needs of these survivors have been largely overlooked in policy and practice development.

More research is needed on the best methods of responding to adolescents who are sexually assaulted and on coordinating needed services across adult and child agencies, Cross said.