Background Self-harm is a well recognised act of psychological distress in some young people. Children and young adults with chronic disease are known to have an increased risk of psychological distress, but their risk of intentional self-harm is not well documented in England. We aimed to determine the risk of intentional self-harm in an English population aged 10–24 years with a range of psychological disorders, namely schizophrenia, bipolar disorder, anorexia/bulimia, depression and in those with chronic medical conditions, including diabetes mellitus, asthma and epilepsy.

Methods We used a dataset of English national linked Hospital Episode Statistics for 1999 – 2011. We identified all the records of people who were admitted to the National Health Service (NHS) hospitals with these conditions. Each condition-specific cohort was constructed by identifying the first admission for the “exposure” condition in people aged 10 to 24 years, and we analysed the dataset for any subsequent admission for intentional self-harm. The rate of self-harm in each exposure cohort was compared with that in a reference cohort comprising people admitted for a wide range of minor medical and surgical conditions; and expressed as a rate ratio (RR) with 95% confidence intervals (CI).

Results The RR (95% CI) for intentional self-harm was significantly and substantially high in people with schizophrenia 5.93 (5.7 to 6.17), bipolar disorder 7.93 (7.26 to 8.64), anorexia/bulimia 5.29 (4.97 to 5.63), and depression 10.25 (9.95 to 10.57). It was also significantly high, though much less so, in people with diabetes 1.60 (1.52 to 1.68), asthma 1.52 (1.48 to 1.56) and epilepsy 1.88 (1.80 to 1.96). These rates remained elevated after we excluded the cases of self-harm in the first year following hospitalisation with each exposure condition.

Conclusion Children and young adults with the psychiatric conditions studied are at substantially increased risk of intentional self-harm. People with the chronic medical diseases studied were also at increased risk, although not nearly as high as that associated with the psychiatric disorders. The elevated risks were maintained more than a year after admission, and are likely to be associated with the disorder rather than the fact of hospital admission. Self-harm is important not only for the distress of the act itself, but it is also recognised as a predictor for eventual suicide. Our findings suggest that current suicide prevention programmes should consider targeting these risk groups as a priority.