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Pokorny's complaint: The insoluble problem of the overwhelming number of false positives generated by suicide risk assessment

  • Olav Nielssen (a1), Duncan Wallace (a2) and Matthew Large (a2)
Summary

Alex Pokorny's 1983 prospective study of suicide found that 96.3% of high-risk predictions were false positives, and that more than half of the suicides occurred in the low-risk group and were hence false negatives. All subsequent prospective studies, including the recent US Army Study To Assess Risk and Resilience in Servicemembers (STARRS), have reported similar results. We argue that since risk assessment cannot be a practical basis for interventions aimed at reducing suicide, the alternative is for mental health services to carefully consider what amounts to an adequate standard of care, and to adopt the universal precaution of attempting to provide that to all of our patients.

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Copyright
This is an open-access article published by the Royal College of Psychiatrists and distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Corresponding author
Correspondence to Olav Nielssen (olavn@ozemail.com.au)
Footnotes
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Declaration of interest

M.L. and O.N. have prepared expert reports for the Coroner and in civil cases about suicides in hospital.

Footnotes
References
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1 Pokorny, AD. Prediction of suicide in psychiatric patients. Report of a prospective study. Arch Gen Psychiatry 1983; 40: 249–57.
2 Pokorny, AD. Suicide prediction revisited. Suicide Life Threaten Behav 1993; 23: 110.
3 Goldstein, RB, Black, DW, Nasrallah, A, Winokur, G. The prediction of suicide. Sensitivity, specificity, and predictive value of a multivariate model applied to suicide among 1906 patients with affective disorders. Arch Gen Psychiatry 1991; 48: 418–22.
4 Madsen, T, Agerbro, E, Mortensen, PB, Nordentoft, M. Predictors of psychiatric inpatient suicide: a national prospective register-based study. J Clin Psychiatry 2012; 73: 144–51.
5 Large, MM, Nielssen, OB. Risk factors for inpatient suicide do not translate into meaningful risk categories – all psychiatric inpatients are high-risk [Author reply]. J Clin Psychiatry 2012; 73: 1034–5.
6 Steeg, S, Kapur, N, Webb, R, Applegate, E, Stewart, SL, Hawton, K, et al. The development of a population-level clinical screening tool for self-harm repetition and suicide: the ReACT Self-Harm Rule. Psychol Med 2012; 42: 2383–94.
7 The Assessment and Management of Risk for Suicide Working Group. Va/DoD Clinical Practice Guideline for Assessment and Management of Patients at Risk for Suicide. Department of Veterans Affairs, Department of Defense, 2013.
8 Kessler, RC, Warner, CH, Ivany, C, Petukhara, MV, Rose, S, Bromet, EJ, et al. Predicting suicides after psychiatric hospitalisation in US Army Soldiers. JAMA Psychiatry 2015; 72: 4957.
9 Szmukler, G, Rose, N. Risk assessment in mental health care: values and costs. Behav Sci Law 2013; 31: 125–40.
10 Mills, PD, King, LA, Watts, BV, Hemphill, RR. Inpatient suicide on mental health units in Veterans Affairs (VA) hospitals: avoiding environmental hazards. Gen Hosp Psychiatry 2013; 35: 528–36.
11 Olfson, M, Marcus, SC, Bridge, JA. Focusing suicide prevention on periods of high risk. JAMA 2014; 311: 1107–8.
12 Knox, KL, Stanley, B, Currier, GW, Brenner, L, Ghahramanlou-Holloway, M, Brown, G. An emergency department-based brief intervention for veterans at risk for suicide (SAFE VET). Am J Pub Health 2012; 102: S337.
13 Molodynski, A, Rugkåsa, J, Burns, T. Coercion and compulsion in community mental health care. Br Med Bull 2010; 95: 105–9.
14 Callaghan, S, Ryan, C, Kerridge, I. Risk of suicide is insufficient warrant for coercive treatment for mental illness. Int J Law Psychiatry 2013; 36: 374–85.
15 Rabone v Pennine Care NHS Foundation Trust [2012] UKSC 2.
16 Large, M, Ryan, CJ, Callaghan, S. Hindsight bias and the overestimation of suicide risk in expert testimony [letter]. Psychiatrist 2012; 36: 236–7.
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BJPsych Bulletin
  • ISSN: 2056-4694
  • EISSN: 2056-4708
  • URL: /core/journals/bjpsych-bulletin
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Pokorny's complaint: The insoluble problem of the overwhelming number of false positives generated by suicide risk assessment

  • Olav Nielssen (a1), Duncan Wallace (a2) and Matthew Large (a2)
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eLetters

Being sensible about suicides

John S Watts, Consultant Psychiatrist, South London and Maudsley NHS Foundation Trust
31 March 2017

I must thank Nielssen, Wallace and Large for their thoughtful and concise piece on the high numbers of false positives produced by assessments of suicide risk, and their conclusions that all patients, even those deemed to be at low risk of suicide, need to receive interventions.1. Having just been to an inquest into the death of a patient where the risk of suicide was deemed to be low, I can readily identify with the sentiments expressed in the paper, namely that our assessments of suicide risk are inadequate, and that we should focus on care for all.

I am reminded of the Dangerous and Severe Personality Disorder (DSPD) Programme in this regard. This was a UK government initiative in response to a high profile case of homicide by a patient with an antisocial personality disorder, where patients who fulfilled certain criteria (at risk of an offence causing serious physical or psychological harm, presence of a severe personality disorder, offending and disorder linked) were admitted to a treatment programme designed to reduce their risk to others. 2. Unsurprisingly there were concerns at the time that large numbers of patients would be incarcerated and prevented from living in the community who would never offend or present a significant risk to others.3. For those who are not aware, the initiative has now ended, following strong opposition from doctors and others.3.

I have long been concerned about the premise that most suicides can be predicted, and now I have some figures and knowledge to quote. Perhaps, like the DSDP Programme, we as a society need to recognise that prediction in retrospect is futile, and follow the paper’s recommendation of the provision of ‘adequate care for all our patients’.

John Watts, Consultant Psychiatrist, South London and Maudsley NHS Foundation Trust, Kent and Medway Adolescent Unit, Staplehurst, UK. Email: john.watts@nhs.net

1. Nielssen O, Wallace D and Large M. Pokorny’s complaint: the insoluble problem of the overwhelming number of false positives generated by suicide risk assessment. BJPsych Bulletin 2017; 41: 18 - 20

2. Probation circular. Dangerous and severe personality disorder (DSPD) programme. http://webarchive.nationalarchives.gov.uk/20060715141954/http://dspdprogramme.gov.uk/media/pdfs/Probation_Circular.pdf accessed 31/03/2017

3. Duggan C. Dangerous and severe personality disorder. The British Journal of Psychiatry 2011; 198 (6) 431 - 33

4. Batty D. Q&A: dangerous and severe personality disorder. The Guardian 17/04/2002. https://www.theguardian.com/society/2002/apr/17/mentalhealth.crime1 accessed 31/03/2017
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