Predictive validity of the PCL-R for offenders with intellectual disability in a high security hospital: treatment progress.
BACKGROUND
Among mainstream offenders, the severe personality disorder of psychopathy has considerable importance as a construct. The disorder has long been associated with failure to make treatment progress. Previous work has identified that psychopathy as a disorder occurs in samples of offenders with intellectual disability (ID), and suggests that the Psychopathy Checklist - Revised (PCL-R: Hare, 1991, 2003) as a measure of the disorder has adequate reliability and validity (Morrissey et al., 2005). The present study aimed to compare the predictive power of the PCL-R in relation to treatment progress with a more general assessment of violence risk, the HCR-20 (Webster, Douglas, Eaves, & Hart, 1997).


METHODS
A sample of 73 residents in a high security intellectual disability service, who had previously been assessed using the PCL-R and the HCR-20, were followed up at 2 years post-assessment, and their outcome determined in terms of two distinct dichotomous variables reflecting definite positive treatment progress and definite negative treatment progress respectively.


RESULTS
In line with predictions, the PCL-R Total score and Factor 1 score (Interpersonal and Affective aspects of psychopathy) and the HCR-20 Total score were significantly inversely associated with a positive move from high to medium security hospital conditions within 2 years of assessment. However against prediction, the PCL-R Total score had incremental validity over the HCR-20. The PCL-R Total and Factor 1, but not the HCR-20 Total score, were also significantly associated with negative treatment progress in terms of a move to more restricted treatment conditions.


CONCLUSIONS
Psychopathy, and in particular its interpersonal and affective manifestations, is a construct which appears to be associated with indirect measures of treatment progress in this high security ID group. However, caution should be applied in the use of a construct with potentially negative connotations in an already devalued population.
Morrissey
Catrin
C
Rampton Hospital, Nottinghamshire Healthcare NHS Trust, Notts, UK. Catrin.Morrissey@nottshc.nhs.uk
Mooney
Paul
P
Hogue
Todd E
TE
Lindsay
William R
WR
Taylor
John L
JL
D000293:Adolescent; D000328:Adult; D000368:Aged; D000987:Antisocial Personality Disorder / Q000175:diagnosis / Q000523:psychology / Q000628:therapy*; D003134:Commitment of Persons with Psychiatric Disorders; D004644:Emotions; D004739:England; D006801:Humans; D007398:Interpersonal Relations; D008297:Male; D008875:Middle Aged; D010552:Personality Assessment / Q000706:statistics & numerical data*; D019989:Persons with Intellectual Disabilities / Q000523:psychology*; D011329:Prisoners / Q000523:psychology*; D011446:Prospective Studies; D011594:Psychometrics / Q000706:statistics & numerical data; D015203:Reproducibility of Results; D012637:Security Measures; D012951:Socialization; D016896:Treatment Outcome; D014754:Violence / Q000517:prevention & control / Q000523:psychology; D014852:Wales