Effect of age-at-release on long term sexual re-offense rates in civilly committed sexual offenders.
A cohort of 136 rapists and 115 child molesters civilly committed to a prison in Massachusetts and followed for 25 years (see Prentky, Lee, Knight, & Cerce, 1997) was examined for the effect of age at time of release on sexual recidivism. The present study (1) examined the recidivism rates for each of five age-at-release groups, separately for rapists and child molesters, (2) tested the fit of linear and quadratic models for 5, 10, 15, 20, and 25-year windows using Cox regression analysis, (3) presented the predicted failure rates for rapists (up to five years post-release) and child molesters (out 21 years post-release), and (4) provided a computational formula for estimating the sexual recidivism rate given an individual's age and number of years post-release. For rapists, a linear model extending 5 years best captured our data (LR=5.62, p<.02). Going out any further than 5 years did not enhance the predictive efficacy of the model. By contrast, a quadratic model extending the full duration of the study (25 years) provided the best fit (LR=6.30, p<.04) for child molesters. Our data supported the general conclusion that risk of sexual recidivism diminishes as a function of increasing age at time of release for rapists. We found marked differences, however, in the re-offense patterns of rapists and child molesters, with the latter group evidencing a distinct quadratic, rather than linear, pattern. Since these findings derive from a population screened for civil commitment by virtue of their presumptive dangerousness, they may not be generalizable to samples of sex offenders drawn from the general prison population.
Prentky
Robert Alan
RA
Research Department, Justice Resource Institute, 63 Main Street, Suite #6, Bridgewater, MA 02324, USA. rprentky@jri.org
Lee
Austin F S
AF
D000293:Adolescent; D000328:Adult; D002648:Child; D002650:Child Abuse, Sexual / Q000523:psychology / Q000706:statistics & numerical data*; D005500:Follow-Up Studies; D006801:Humans; D007326:Institutionalization / Q000706:statistics & numerical data*; D016014:Linear Models; D008137:Longitudinal Studies; D008297:Male; D008404:Massachusetts / Q000453:epidemiology; D008605:Mental Health Services / Q000706:statistics & numerical data; D008875:Middle Aged; D011329:Prisoners / Q000523:psychology / Q000706:statistics & numerical data*; D016016:Proportional Hazards Models; D012372:ROC Curve; D011902:Rape / Q000523:psychology / Q000706:statistics & numerical data*; D012044:Regression Analysis; D018570:Risk Assessment / Q000379:methods*; D055502:Secondary Prevention; D020018:Sexual Dysfunctions, Psychological / Q000453:epidemiology