Mental Illness and Serious Harm to Others - University of Liverpool

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NHS National Programme on Forensic Mental Health Research and Development numerically tamed. There are numerous grounds for questioning this as anything but fantasy, which are better dealt with in the reviews already listed (Adams, 1995; Conner and Norman, 1996), but if evidence more specific to this field were to be required, there is plenty. Monahan and Steadman (1996) have used a meteorology model and shown how often predictions can be wrong, even in a field where use of prediction has a long history and there is an enormous wealth of data - both past and present - on which to base predictions. Comparative studies of clinical and actuarial predictions conflict to the extent that the same authors, in different combinations, working with the same data, come to different conclusions on it. Lidz, Mulvey and Gardner (1993) found clearly in favour of 'clinical’ predictions for men, by one methodology, while Gardner, Mulvey and Shaw (1995), and Gardner et al (1996), found clearly in favour of the actuarial. These different conclusions were drawn by the same team of researchers working with the same data, but using different statistical models. Mossman (1994) provides an important analysis of the analytic difficulties in this field. (For more detail and specifics of some of the mathematics involved, see also Mossman, 1995.) With the one caveat that past behaviour alone appears to be a better long-term predictor of future violence than clinical judgements, Mossman's interpretation of the collective data to that point is that mental health professionals are substantially more accurate than chance in their violence predictions. Grove and Meehl (1996) assert that from 136 'studies over a wide range of predictards' (i.e. including violence but a lot else besides, and not solely within mental health), 'predictards' favour 'mechanical' algorithmic prediction procedures over the clinical. This is a passionately argued paper which includes the following statement: 'We conclude that this literature is almost 100 per cent consistent ... [with] results obtained by Meehl in 1954. Forty years of additional research ... has not altered the conclusion ... It has only strengthened that conclusion.' He may be right, but one is certainly left with the sense that Meehl has no truck with dissent. Most assessment tools which have been advanced as of potential value in the prediction of violence depend heavily on this past behaviour / future behaviour equation, for example the Violence Risk Appraisal Guide (VRAG), but are lengthy and difficult to complete. Evidence for effectiveness in the jurisdiction in which they are invented (Quinsey et al, 1998) is not necessarily replicated in others (Thomson, personal communication), and they are generally reliant on an established pattern of violence. Interesting models, with face validity and apparently sound if complex mathematical properties, such as the 'decision tree’ approach (Steadman et al, 2000), are neither established as practical tools in ordinary clinical situations, nor, indeed, tested as prediction instruments. The decision tree has in common with so much other work in this area the fact that it has been derived from testing correlations between factors over time, albeit prospectively, and not tested as a prediction tool. Any test of a tool in clinical practice, however, will be confounded by the facts that, in practice, management follows from assessment, and management, by definition, is designed to prevent the prediction coming true. Until an adequate model is derived to allow for that, uncertainty about the predictive powers of such instruments must remain. 15
NHS National Programme on Forensic Mental Health Research and Development 4. Gaps in the Knowledge 4.1 Perception of the need for answers At the end of 1999, the National Programme on Forensic Mental Health R&D conducted a survey of 638 people across England and Wales covering a range of clinicians and managers, prison and probation services, researchers supported by the programme and service users. One-third responded, with some variation between constituencies, but at least some response from each. Most questions on mental illness were directed towards risk assessment, and even the one specifically phenomenological question was about symptoms and risk: are symptoms of psychosis directly related, indirectly related, or unrelated to violence? Some interesting variants of this question occurred within the risk cluster : ❑ What are the origins of psychotic symptoms, specifically delusions? ❑ Do the childhood experiences of a psychotic individual contribute to the content of their delusions? ❑ Does such content contribute to the process of risk assessment? These questions are not only important in themselves, but also as an indicator of a whole tranche of longitudinal work needed which is well advanced in relation to offending (see Farrington, 1993) but not in relation to mental illness. It cannot be assumed that antecedents to violence are necessarily the same between ill and healthy people - or even between people with illness and people with personality disorder. More sophisticated post-offending longitudinal studies are also needed to clarify cycles in apparently relevant symptomatology and / or its continuing relevance and interaction between mental state, violence, and treatment and management strategies. Elements of the broader picture are in place which should give some assistance in developing testable overall management strategies, but clinical detail is still largely lacking. 4.2 Management questions Management questions, as such, were few and limited, with the most interesting being posed in the context of risk, and dealt with under that heading. Among the other two, one respondent mused on processes to enhance identification at entry points to the criminal justice system. Here, it seems to me that it would be a relatively easy matter to select a few simple self-rating questionnaires to supplement prison medical officer screening examinations. A possible package might be any or all of: ❑ the General Health Questionnaire (GHQ) (Goldberg, 1972), which covers mainly anxiety and depression. It has been used successfully among prisoners (e.g. Gunn et al, 1978) 16
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Mental Illness and Serious Harm to Others - University of Liverpool

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