Children and teenagers admitted to hospital with injuries relating to drugs, alcohol, violence or self-harming face a five-fold increased risk of suicide, a study has found.
Researchers looked at anonymous data on more than a million young people aged 10 to 19 who were admitted to UK hospital accident and emergency departments between 1997 and 2012.
Those whose injuries were due to "adversity" - meaning they were the result of alcohol or drug abuse, self-harm or violence - were twice as likely to die in the next 10 years as those hurt in accidents.
Young people in the "adversity" group were also five times more likely to kill themselves over the decade.
Investigator Professor David Cottrell, from the University of Leeds, said: "Clinicians have not fully appreciated the risks facing children and young people who arrive in hospital emergency departments having suffered an adversity-related injury.
"It is well established that children who self-harm are at an increased risk of suicide.
"But the research points to that fact that the risk extends to a much broader group.
"Children and young people who suffered injuries through drink or drugs or violence also faced an increased risk of suicide or premature death through alcohol and drug behaviours."
The death rate for boys in the adversity group was 15.6 per 1,000 and for girls 7.3 per 1,000.
Two thirds of recorded deaths were attributable to suicide, drug or alcohol abuse, or homicide, the study published in The Lancet medical journal showed.
Sarah Brennan, chief executive of the charity Young Minds, said: "This groundbreaking research demonstrates some of the interconnections between self-harm, substance misuse and violent injury - and the tragic consequences that these experiences may have.
"It is essential that we don't think of young people simply in terms of a list of 'issues', and that we understand how distress can be expressed in different ways at different times."