Are people with mental disorders more likely to be killed than others? BMJ.March.2013

11.03.2013

Homicides by mentally ill always catch headlines. Stigmatising portrayals of mentally ill as ‘risk to others safety’ continues across cultures. This adds to the stigma and marginalisation of the mentally ill.

What about the risk of being killed?  Are people with mental disorders more vulnerable to homicidal death?

Casey Crump , Kristina Sundquist, Marilyn A Winkleby and Jan Sundquist  investigated this question by using the best data available to do this. The national psychiatric registers of Scandinavian countries are  the gold mines of mental health data. These investigators used the Swedish National Psychiatry Register and linked it to the  complete cause specific mortality records. They used both inpatient and outpatient data to give a more realistic and broader picture. There were 7253516 participants who were followed up for 8 yrs. 615 homicides occurred during the 54.4 million person years of follow-up.

Findings:

Compared with people without psychiatric disorders,  those diagnosed with any mental illness have a relative risk of 4.9 of death by homicide. This is the relative risk after adjusting for socio demographic confounders.

Risk of death by homicide was highest among people with substance use disorders .Those with substance use disorders were at 9 fold risk than general population. Risk is increased across all mental disorders including anxiety disorders and depression. It is important to note that depression is attached with 2.6 fold risk increase for death by homicide where as schizophrenia is increased by 1.8 fold. Substance use do not explain the increased risk in these disorders. Being male, unmarried and of low socio economic class increase the risk in general.

Limitations: The cohort studied include only those who were diagnosed ( i.e. do not have information on undiagnosed mental disorders in the population). Universal access to health care in Sweden makes this less of a problem.

Strength: Large and most complete database.This is the first time both inpatient and outpatient data is used to give a more realistic picture. Results are similar to previous studies.

Conclusions/comments: Clinicians traditionally focus the risk assessments on suicide and harm to others. We need to be  aware of the range of adverse outcomes our patients are likely to have. Risk assessments may need to reflect the chances of being a victim of violence as well as of committing it.

In the accompanying editorial  Webb, Shaw and Appleby   highlights the still unanswered questions. Do the ‘risk from others’  have anything to do with the increase in suicide among recently  discharged patients?  Is the risk from community making these individuals take their life? What would it look like if we were to compare the risk of  committing homicide with the risk of being a victim of it?  Interesting and important questions.

Summary of the article:

Mental disorders and vulnerability to homicidal deathSwedish nationwide cohort study. Crump C, Sundquist K, Winkleby MA, Sundquist J. BMJ. 2013 Mar 4;346

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