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Preventing (Versus Predicting) Violence After Release

Researchers search for the proximate causes of violence in criminal psychiatric patients.
(Photo: hikrcn/Shutterstock)

(Photo: hikrcn/Shutterstock)

Maybe the most important job when considering releasing a violent psychiatric patient is deciding whether that patient is going to hurt somebody else once they're out. Unfortunately, according to a paper published in PLoS One, the standard tools used to assess patients' risk of violence aren't particularly good at preventing violence—but may contain clues for how to do just that.

At issue is a set of methods known as Structured Professional Judgment, in particular two very popular methods: the Historical Clinical Risk Management 20—a 20-question survey that incorporates a patient's history of violence, employment, substance abuse, and other factors to assess the risk of future violence—and a similar method called the Structured Assessment of Protective Factors (SAPROF). In theory, SPJ methods bridge a gap between a psychiatrist's opinion and so-called actuarial approaches, which search for any and all correlations between patient histories and violence, and use those correlations to make individualized predictions about each patient's level of risk.

Violent thoughts, instability, difficulty coping with stress, and poor self-control were associated with two- to three-fold increases in the risk of violence.

SPJ certainly has its proponents, but, Jeremy Coid and his colleagues argue in the new study, the strategy's got a few things working against it. First, there's not much evidence that it's actually an accurate way to predict whether a patient will be violent. Second, like actuarial methods, SPJ emphasizes using a wide range of variables to predict future violence rather than identifying a narrower set of more proximate causes underlying a violent act.

The researchers began to address those issues by tracking 409 patients who'd been locked up in National Health Service psychiatric hospitals in England and Wales following violent and criminal behavior, and were subsequently released between September 2010 and August 2011. The researchers administered to the former patients the HCR-20, the SAPROF, and a third survey around the time of their release, once more six months later, and again one year later. The researchers' goal: to identify violent acts, such as threatening someone with a knife, that former patients may have committed.

The team first looked for correlations between individual HCR-20 and SAPROF items and violence six and 12 months down the road. The results were neither terrible nor particularly great; a coin flip would have been as good a predictor for violence as eight HCR-20 items and four (out of 17) SAPROF items, though others fared better.

But the most useful results, the team argues, came when they looked for links between HCR-20, SAPROF, and violence surveys taken around the same time as each other. Violent thoughts, instability, difficulty coping with stress, and poor self-control were associated with two- to three-fold increases in the risk of violence, while self- control was associated with an 80 percent reduction. Inadequate support systems, poor living situations, and poor treatment responses had no effect, except when accompanied by violent thoughts.

Those results, the team writes, suggest that working to keep patients' mental health stable and targeting symptoms of psychosis, such as violent thoughts, may be the most useful ways to prevent violence.


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