University of Manchester researchers have found that reports of self-harm in girls aged between 13 and 16 rose by 68% between 2011 and 2014. Overall, girls had much higher rates than boys.

The study, published in the British Medical Journal and carried out in over 600 general practices, also found that young people living in the most socially deprived areas with often the most complex needs, were the least likely to be referred to specialist services.

The study was funded by The National Institute for Health Research.

Self-harm - intentional self-poisoning or self-injury - in children and adolescents is a major public health issue in countries across the world. Experts acknowledge self-harm as the biggest risk factor for subsequent suicide. Suicide is now the second most common cause of death in the under 25s worldwide.

Unlike most previous studies, Dr Cathy Morgan and a team from The University of Manchester, examined self-harm recorded in general practice rather than in hospital.

To estimate rates of self-harm, they analysed data for 16,912 patients aged between 10-19 years from 674 general practices, who harmed themselves during 2001 to 2014.

To assess mortality, they compared data from 8,638 of the patients with 170,274 unaffected children, matched by age, gender and general practice.

For girls, the rate of self-harm was 37.4 per 10,000, much higher than 12.3 per 10,000 in boys. It rose by 68% in girls aged 13 to 16 from 45.9 per 10,000 in 2011 to 77.0 per 10,000 in 2014.

Referrals to specialist mental health services within 12 months of self-harming were 23% less likely for young patients registered in practices in the most deprived areas, even though the rates of self-harm were higher in these areas.

Children and teenagers who self-harmed were nine times more likely to die unnaturally than unaffected young people with an especially marked increased risk of suicide and acute alcohol/drug poisoning death.