Around four in 10 US teens with eating disorders also intentionally harm themselves, usually by cutting, and the rate could be higher because clinicians don't routinely screen for self-injury, a study published Thursday shows.
"These are very high numbers, but they're still conservative estimates," because doctors and other care-givers don't always ask young patients about self-injury, said Rebecka Peebles, a lead author of the study conducted by researchers from Stanford University and Lucile Packard Children's Hospital.
"If you see an innocent-looking 12-year-old boy, you don't even think of asking about self-injurious behavior. We ask 97 percent of children 12 years and up if they smoke cigarettes; we need to get that good with screening for self-injurious behavior," she said.
For the study, published in the Journal of Adolescent Health, researchers examined the records of 1,432 patients, ages 10-21, who were admitted to the eating disorders program at Packard Children's Hospital in California from January 1997 through April 2008.
Just over 90 percent of the patients were female, three-quarters of them white, and their average age was 15. Many of them had a history of binging and purging, or bulimia nervosa.
Nearly 41 percent said they had inflicted physical harm on themselves, in the vast majority of cases by cutting.
But only around half the youngsters who checked into the eating disorders program were even asked if they intentionally injured themselves -- and those who were usually fit the profile of a self-injurer: older, white, female, suffering from bulimia nervosa, or with a history of substance abuse.
"The question is, are we missing other kids who are not meeting this profile?" Peebles said.
The study did not examine the reasons behind self-injury but Peebles said her clinical experience suggested patients "are trying to feel pain" and feel "release that comes when they cut or burn themselves."
Other studies have shown that between 13 and 40 percent of all adolescents engage in some form of self-injury, which has been associated with a higher risk of suicide.