Suicide following presentation to hospital for non-fatal self-harm in the Multicentre Study of Self-harm: long-term follow-up study

Background: Self-harm is the strongest risk factor for subsequent suicide but risk may vary. We compared the risk of suicide following hospital presentation for self-harm according to patient characteristics, method of self-harm and variations in area-level socioeconomic deprivation, and estimated the incidence of suicide by time after hospital attendance. Method: All self-harm presentations (N=90,614, involving 49,783 individuals) to hospitals in the Multicentre Study of Self-harm in England (1/1/2000 to 31/12/2013) were included, with mortality follow-up from 1/1/2000 to 31/12/2015. Information on method of self-harm was obtained through systematic monitoring in hospitals. Level of socioeconomic deprivation was based on the Index of Multiple Deprivation (IMD) characterising the area where patients lived, grouping them according to IMD quintiles. We calculated incidence rates of suicide since first hospital presentation by follow-up period and estimated the association between individual factors (method of self-harm, IMD) and suicide using mixed effect models. Findings: By the end of follow-up 703 patients had died by suicide. The highest incidence of suicide was in the first year after hospital discharge, particularly in the first month. Risk was three times greater in males than females [odds ratio (OR) 3·36, 95% CI 2·77-4·08, p<0·0001] and increased with age at hospital presentation (OR 1·03, 95% CI 1·03-1·04, p<0·0001). Relative to hospital presentations after self-poisoning alone, presentations involving both self-injury and self-poisoning were associated with higher suicide risk [adjusted odds ratio (aOR) 2·06, 95% CI 1·42-2·99, p<0·0001], as were presentations after self-injury alone (aOR 1·36, 95% CI 1·09-1·70, p=0·007). Similarly, attempted hanging or asphyxiation (aOR 2·70, 95% CI 1·53-4·76, p=0·001) and transport-related injuries (aOR 2·99, 95% CI 1·17-7·65, p=0·02) were associated with heightened suicide risk. Self-cutting combined with self-poisoning was also associated with increased risk (aOR 1·36, 95% CI 1·08-1·71, p=0·01). Patients from the least and 2nd least deprived IMD quintiles were more likely to die by suicide than patients in the most deprived IMD quintile (aOR 1·76, 95% CI 1·32-2·34, p