Suicidal Intent and Method of Self-Harm: A Large-scale Study of Self-Harm Patients Presenting to a General Hospital

Data from the Oxford Monitoring System for Attempted Suicide (2004-2011) were used to study hospital presentations for self-harm in which Suicidal Intent Scale (SIS) scores were obtained (N = 4,840). Regression of medians was used to control for the confounding effect of age and gender. Higher estimated median SIS scores were associated with increasing age, male gender, self-poisoning versus self-injury, multiple methods of self-harm versus self-injury alone, use of gas (mainly carbon monoxide), dangerous methods of self-injury (including hanging, gunshot), and use of alcohol as part of the act. For self-poisoning patients, there was a correlation between the number of tablets taken and the total SIS score. Compared with self-poisoning with paracetamol and paracetamol-containing compounds, self-poisoning with antipsychotics was associated with a lower median SIS score while antidepressants had the same estimated median as paracetamol. Use of alcohol within 6 hours of self-harm was associated with lower SIS scores. In conclusion, certain methods of self-harm, particularly dangerous methods of self-injury and self-poisoning with gas, were associated with high intent and should alert clinicians to potential higher risk of suicide. However, apart from use of gas, suicidal intent cannot be inferred from type of drugs used for self-poisoning.