Predicting Violence Using Risk Assessment Instruments or Gut Instinct?

Occasionally a psychiatric consultant is asked to assess the risk for violence in a patient who makes caregivers nervous. Often a clinician relies on a gut instinct to tell whether or not a patient might be at high risk for harming others. This isn’t so far-fetched and books have been written about this sort of sixth sense [1]. This is entertaining but highly unreliable in the real world of psychiatric consultation in a general hospital. In fact, it’s extremely difficult to predict who is going to be violent in the hospital or in any setting. Many patients are likely to react with intense grief, anger, and confusion when confronted with bad news or the myriad other frustrations which medical hospitalization can incur. There are many assessment instruments available which purport to measure the risk for violence (see reference below to free and open access article) [2]. The systematic review identifies a handful which are only moderately useful at best and many are typically used in forensic settings.

What about predicting violence from patients in a general hospital? Gut instincts are rarely useful and often muddied by reliance on stereotypes and influenced by several extraneous factors including local laws, law enforcement culture, hospital policies, and even how bad a day a clinician is having. I know about this because I’m prey to them, like any human. The struggle to remain aware of the risk of under calling or over calling foreseeable risk for violence is a daily one and fraught with uncertainty. The consequences run the gamut from bad for business to deadly. The field is anything but evidence-based. You can’t rely on an assessment tool or your gut alone. One study using brain MRIs found structural differences in gray matter volumes in areas importan in empathy in violent antisocial men with psychopathy compared to those without psychopathy, but we’re not going to screen everyone with that method [3].

In the end, I often try to use some combination of common sense, my training in psychiatric assessment, and my gut. But frankly, I’ve never used an assessment instrument. Often by the time I’m called to the scene, it’s a little late for that.

There are many reasons for violence and they’re not all strictly psychiatric. Delirium can make patients violent, and so can drugs, certain kinds of medical treatment, brain injuries, poverty, war, bad laws, bad luck, hunger, and injustice–and the list goes on. I guess we just have to decide whether we think a psychiatrist can cover all that.

Related Posts:

September 19, 2011: Who’s a Criminal? Antisocial Personality Disorder in the General Hospital, Who’s a Criminal? Antisocial Personality Disorder in the General Hospital – The Practical Psychosomaticist: James Amos, M.D.

Ever Wonder What the Difference Between a Sociopath and Psychopath? « Profiles of Murder

1. De Becker, G. (1997). The gift of fear : survival signals that protect us from violence. Boston, Little, Brown.

2. Fazel, S., J. P. Singh, et al. (2012). “Use of risk assessment instruments to predict violence and antisocial behaviour in 73 samples involving 24 827 people: systematic review and meta-analysis.” BMJ: 1-12.


Objective To investigate the predictive validity of tools commonly used to assess the risk of violence, sexual, and criminal behaviour.

Design Systematic review and tabular meta-analysis of replication studies following PRISMA guidelines.

Data sources PsycINFO, Embase, Medline, and United States Criminal Justice Reference Service Abstracts.

Review methods We included replication studies from 1 January 1995 to 1 January 2011 if they provided contingency data for the offending outcome that the tools were designed to predict. We calculated the diagnostic odds ratio, sensitivity, specificity, area under the curve, positive predictive value, negative predictive value, the number needed to detain to prevent one offence, as well as a novel performance indicator—the number safely discharged. We investigated potential sources of heterogeneity using metaregression and subgroup analyses.

Results Risk assessments were conducted on 73 samples comprising 24 847 participants from 13 countries, of whom 5879 (23.7%) offended over an average of 49.6 months. When used to predict violent offending, risk assessment tools produced low to moderate positive predictive values (median 41%, interquartile range 27-60%) and higher negative predictive values (91%, 81-95%), and a corresponding median number needed to detain of 2 (2-4) and number safely discharged of 10 (4-18). Instruments designed to predict violent offending performed better than those aimed at predicting sexual or general crime.

Conclusions Although risk assessment tools are widely used in clinical and criminal justice settings, their predictive accuracy varies depending on how they are used. They seem to identify low risk individuals with high levels of accuracy, but their use as sole determinants of detention, sentencing, and release is not supported by the current evidence. Further research is needed to examine their contribution to treatment and management.

BMJ 2012; 345:e4692

This is an open-access article distributed under the terms of the Creative Commons Attribution Non-commercial License, which permits use, distribution, and reproduction in any medium, provided the original work is properly cited, the use is non commercial and is otherwise in compliance with the license. See: and

3. Gregory, S., D. Ffytche, et al. (2012). “The Antisocial Brain: Psychopathy Matters: A Structural MRI Investigation of Antisocial Male Violent Offenders.” Arch Gen Psychiatry.

CONTEXT: The population of men who display persistent antisocial and violent behavior is heterogeneous. Callous-unemotional traits in childhood and psychopathic traits in adulthood characterize a distinct subgroup. OBJECTIVE: To identify structural gray matter (GM) differences between persistent violent offenders who meet criteria for antisocial personality disorder and the syndrome of psychopathy (ASPD+P) and those meeting criteria only for ASPD (ASPD-P). DESIGN: Cross-sectional case-control structural magnetic resonance imaging study. SETTING: Inner-city probation services and neuroimaging research unit in London, England. PARTICIPANTS: Sixty-six men, including 17 violent offenders with ASPD+P, 27 violent offenders with ASPD-P, and 22 healthy nonoffenders participated in the study. Forensic clinicians assessed participants using the Structured Clinical Interview for DSM-IV and the Psychopathy Checklist-Revised. MAIN OUTCOME MEASURES: Gray matter volumes as assessed by structural magnetic resonance imaging and volumetric voxel-based morphometry analyses. RESULTS: Offenders with ASPD+P displayed significantly reduced GM volumes bilaterally in the anterior rostral prefrontal cortex (Brodmann area 10) and temporal poles (Brodmann area 20/38) relative to offenders with ASPD-P and nonoffenders. These reductions were not attributable to substance use disorders. Offenders with ASPD-P exhibited GM volumes similar to the nonoffenders. CONCLUSIONS: Reduced GM volume within areas implicated in empathic processing, moral reasoning, and processing of prosocial emotions such as guilt and embarrassment may contribute to the profound abnormalities of social behavior observed in psychopathy. Evidence of robust structural brain differences between persistently violent men with and without psychopathy adds to the evidence that psychopathy represents a distinct phenotype. This knowledge may facilitate research into the etiology of persistent violent behavior.