Method used in an unsuccessful suicide attempt predicts likelihood of future completed suicide
Does the method used in an unsuccessful suicide attempt predict the likelihood of subsequent completed suicide?
48 649 individuals (age 10 and over) admitted to hospital between 1973 and 1982 after definite or uncertain attempted suicide (International Classification of Diseases, Revision 8 (ICD-8) codes E950-9 and E980-9). All individuals who attempted suicide in this period were identified using Swedish national hospital discharge registers. For individuals with multiple suicide attempts, the first was considered the index event. People who immigrated within 2 years prior to the index event were excluded to avoid confounding by the stress of asylum seeking.
General population, Sweden; 1973–2003.
Method of index suicide attempt (identified using ICD codes). People attempting suicide by poisoning were used as the reference group as it was the most common method.
Attempted suicide, definite or uncertain suicide (ICD-8-9 codes E950-9 and E980-9; ICD-10 codes X60–84 and Y10–34). Follow-up finished after death from any cause, or emigration. Analyses were adjusted for age, gender, education, immigrant status and psychiatric disorders.
Retrospective cohort study (registry based).
Twelve per cent of participants (5740 out of 48 649 people) committed suicide during follow-up, and 4.2% had committed suicide within 1 year of the index attempt. People who had attempted suicide by hanging, strangulation or suffocation were significantly more likely to have later successful suicide than those who attempted suicide by poisoning (adjusted HR 6.2, 95% CI 5.5 to 6.9). Risk of completed suicide was also significantly increased among those who attempted suicide by drowning, firearm or explosives, jumping from a height or gassing (see table 1). People who attempted suicide by cutting or piercing, or by other methods, or those who were admitted for the late effects of suicide attempt or other self-inflicted harm were not at increased risk of later competed suicide compared with those who had attempted suicide by poisoning. Most of those who successfully committed suicide used the same method as they did at the index attempt.
The method used in an unsuccessful suicide attempt predicts likelihood of a subsequent completed suicide attempt. People who attempt suicide by hanging, drowning, firearms or explosives, jumping from a height or gassing are at greater risk of future completed suicide compared with those who attempt suicide by poisoning, and this should be taken into account when planning aftercare.
Sources of funding Stockholm County Council and Karolinska Institutet.
Suicide risk assessment protocols and conceptual/predictive models of suicide often include access to lethal means and prior attempts as factors associated with increased suicide risk. Characteristics of the method (ie, lethal vs non-lethal) used in an attempt are often included in assessments and models but not the specific method (eg, firearms, hanging, self-poisoning, etc).
The results of the study showed that the method used in an index suicide attempt hospitalisation predicted suicide. As compared with those who were hospitalised for a suicide attempt involving self-poisoning, it was found that those hospitalised for suicide attempts involving hanging, strangulation and suffocation had over sixfold greater risk for eventual suicide. The authors also examined (1) whether the method used in a prior suicide attempt requiring hospitalisation was the same method used in fatal suicide and (2) whether prior hospitalisations for psychotic, affective or another psychiatric disorder were independent risk factors for suicide. The proportion of patients who used the same method in the index suicide attempt and the eventual suicide was most frequent among those who attempted suicide using hanging, strangulation, suffocation and drowning. Patients with psychotic disorders who used hanging in a prior suicide attempt were at highest risk for suicide.
Methods used in a suicide attempt may be influenced by multiple individual and societal factors including suicide intent, availability and accessibility of specific methods, as well as cultural factors. Legislation restricting access to highly lethal methods such as firearms and pesticides as well as the detoxification of domestic gas has been among the most promising population-level means of suicide prevention.1 This study shows that the specific method used in a previous suicide attempt is associated with prognosis. The take home message is that intensified aftercare is warranted for those who attempt suicide using violent methods.