The World Health Organization estimates that, as of 2010, 880,000 deaths occur as a result of self-harm. About 10% of admissions to medical wards in the UK are as a result of self-harm, the majority of which are drug overdoses. However, studies based only on hospital admissions may hide the larger group of self-harmers who do not need or seek hospital treatment for their injuries, instead treating themselves. Many adolescents who present to general hospitals with deliberate self-harm report previous episodes for which they did not receive medical attention. In the United States up to 4% of adults self-harm with approximately 1% of the population engaging in chronic or severe self-harm.