Homicide in discharged patients with schizophrenia and other psychoses: A national case-control study
Introduction
Between 10–20% of homicide perpetrators have psychosis (Eronen et al., 1996a, Eronen et al., 1996b, Fazel & Grann, 2004), an increased risk for homicide of around 20 times in individuals with schizophrenia and other psychoses compared with general population controls (Fazel et al., 2009a, Fazel et al., 2009b). Although risk factors for violence in individuals with schizophrenia have been studied (Fazel et al., 2009a, Walsh et al., 2004, Soyka et al., 2007), little is known about what factors are associated with homicide in psychosis. Clinical studies investigating homicide perpetrators have focused on clinical characteristics, but without appropriate comparison groups, they are not able to explore potential risk factors. Within-group designs have demonstrated comorbid substance abuse significantly increases the risk of homicide in individuals with schizophrenia (Eronen et al., 1996a, Eronen et al., 1996b, Schanda et al., 2004). In addition, there is evidence that treatment mediates risk. Those with first episode psychosis have higher rates of homicide than individuals after their first episode (Nielssen and Large, 2008).
Therefore, we aimed to undertake a case control study to investigate factors associated with homicide after discharge from psychiatric hospital in individuals with psychosis. This design has two advantages. First, it allows identification of factors that distinguish patients who were at future risk at committing homicide from patients who were not. Second, by investigating homicide only after discharge from hospital, it has the potential to inform clinical risk assessment. To our knowledge, this is the first such study that uses a control population with psychosis. We hypothesized that important factors associated with homicide in schizophrenia would be potentially treatable.
Section snippets
Methods
In Sweden, all residents are given a ten-digit unique identification number making linking of data in national registers possible. We linked two nationwide population-based registries in Sweden: The Hospital Discharge Registry (HDR; held at the National Board of Health and Welfare), and the National Crime Register (National Council for Crime Prevention).
The Hospital Discharge Register monitors all psychiatric hospitals and is the largest inpatient register worldwide. Reporting to the register
Results
A total of 2,005 individuals committed 2,093 homicides 1988–2001. The average population in Sweden for those aged 15 and over was 7,176,361, which equates to an overall rate of 28 homicide perpetrators per 100,000 persons in the Swedish criminally responsible population. Overall, 409 homicide offenders had a psychosis diagnosis out of a total number of 98,092 patients discharged with schizophrenia and other psychoses (equivalent to a rate of 417 homicide perpetrators per 100,000 patients with
Discussion
We report a national case-control study of patients with psychosis, of whom 47 committed a homicide within 6 months of discharge. These were compared with 105 patients with psychosis who were not convicted of any violent offence after discharge. This design enabled exploration of factors associated with homicide in patients leaving hospital that could potentially inform violence risk assessment and management. As the number of cases was small, our findings should be interpreted primarily as
Conclusion
Homicide by psychiatric patients is rare but an event of considerable consequences. In addition to the effects on the family and friends of victims, the impact on services and professionals is also noteworthy as questions of accountability and responsibility are inevitably raised. The public image of the psychiatry, stigma suffered by patients (Corrigan et al., 2002, Van Dorn et al., 2005), and even recruitment into the profession (Lambert et al., 2006) are likely longer term consequences of
Role of the funding source
This project was funded by the Stanley Medical Research Institute (grant#04R-780).
Contributors
SF and MG designed the study and wrote the protocol. PB and VR assisted with the administration of the project and supervision of research assistants, and PB with the data analysis. SF did the data analysis and prepared the first draft. All authors contributed to revisions and a final draft.
Conflict of interest
The authors report no conflict of interest.
Acknowledgements
We are grateful to Ms Andrea Mogues for the data extraction, to Dr John Powell and Dr Julia Sinclair for sharing with us data extraction sheets that we adapted for this study, and Ms Lena Andersson for extracting data for the interrater reliability study.
References (32)
- et al.
Effects of the atypical antipsychotic risperidone on hostility and aggression in schizophrenia: a meta-analysis of controlled trials
Eur. Neuropsychopharmacol.
(2001) - et al.
Psychopathy and institutional outcome in patients with schizophrenia in forensic settings in the UK
Schizophr. Res.
(2006) - et al.
Incipient offending among schizophrenia patients after first contact to the psychiatric hospital system
Eur. Psychiatry
(2005) - et al.
Clinical correlates of later violence and criminal offences in schizophrenia
Schizophr. Res.
(2007) - et al.
Predicting violence in schizophrenia: a prospective study
Schizophr. Res.
(2004) - et al.
Pharmacotherapy of schizophrenia with comorbid substance use disorder—Reviewing the evidence and clinical recommendations
Progress Neuropharm. Biol. Psychiatry
(2008) - et al.
Violence in psychosis: estimating the predictive validity of readily accessible clinical information in a community sample
Schizophr. Res.
(2008) - et al.
Violence and delusions: data from the MacArthur Violence Risk Assessment Study
Am. J. Psychiatry
(2000) - et al.
Challenging two mental illness stigmas: personal responsibility and dangerousness
Schizophr. Bull.
(2002) - et al.
Young cases of schizophrenia identified in a national inpatient register. Are the diagnoses valid?
Soc. Psychiatry Psychiatr. Epidemiol.
(2002)
Evaluation of diagnostic procedures in Swedish patients with schizophrenia and related psychoses
Nord. J. Psychiatry
Mental disorders and homicidal behavior in Finland
Arch. Gen. Psychiatry
Schizophrenia and homicidal behavior
Schizophr. Bull.
Psychiatric morbidity among homicide offenders: a Swedish population study
Am. J. Psychiatry
The population impact of severe mental illness on violent crime
Am. J. Psychiatry
Risk factors for violent crime in schizophrenia: a national cohort study of 13, 806 patients
J. Clin. Psychiatry
Cited by (69)
National clinical study of violent and homicidal patients hospitalized in France's psychiatric high security care units
2024, Annales Medico-PsychologiquesThe phenomenon of overkill in northern Greece: A descriptive forensic psychiatric study between 2015 and 2020 on criminal offenders found not guilty by reason of insanity
2022, Journal of Forensic and Legal MedicineCitation Excerpt :As regards the Positive and Negative Syndrome Scale (PANSS) at the time the crime was committed, offenders showed significantly higher scores for symptoms of schizophrenia, with seven-fold more offenders scoring above average (p < 0.001) [overall mean value 33.826–45]. Regarding the Negative scale, moderately higher levels were exhibited by female offenders (p = 0.087) [overall mean value 25.412–40], while the General Psychopathology scale disclosed significantly more (2.4-times) offenders scoring below average (p = 0.00386) [overall mean value 57.639–78]. The overall PANSS Total score mean value was estimated at 116.8 (92–150), while comparative scores for other subcategories were unremarkable.
Impulsive and aggressive traits and increased peripheral inflammatory status as psychobiological substrates of homicide behavior in schizophrenia
2022, European Journal of PsychiatryCitation Excerpt :The majority of individuals with schizophrenia are not considered to be dangerous to society, and their contribution to the overall homicide rate is small. However, an association between schizophrenia and homicide has not only been established in the public mind and law, but has also been demonstrated in epidemiological research.1–5 This association appears to be complex and is largely mediated by factors distinct from the diagnosis itself.
Characteristics and particularities of homicides committed by schizophrenics
2022, Annales Medico-Psychologiques