Evaluating Community Sex Offender Treatment Programs: A 12-Year Follow-Up of 724 Offenders

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Although some studies suggest positive effects of treatment for sexual offenders, most studies have been hampered by the unknown influence of selective attrition (e.g., volunteers and drop-outs). In the 1980s, the Correctional Service of Canada began to require weekly community treatment sessions for all sex offenders released in the Pacific Region. This policy change provided a unique opportunity for comparing an unselected cohort of treated sex offenders (n = 403) to an untreated cohort (n = 321) released in earlier years. After an average 12-year follow-up period, no differences were observed in the rates of sexual (21.1% vs 21.8%), violent (42.9% vs. 44.5%) or general (any) recidivism (56.6% vs 60.4%) for treated and untreated groups, respectively. The outcome remained comparable after controlling for length of follow-up, year of release, age, and seven static risk factors coded from official criminal history records. Retrospective ratings of the treatment quality also showed no relationship to observed recidivism rates. The static risk factors coded in the current study accounted for considerable variance in recidivism and could easily be used to improve statistical controls in future evaluations.


Meme si certaines etudes laissent croire a des effets positifs du traitement des delinquants sexuels, la plupart des etudes ont ete retardees par l'influence inconnue de l'attrition selective (p. ex., les volontaires et les decrocheurs). Au cours des annees 1980 le Service correctionnel du Canada a commence a exiger des seances de traitement communautaire pour tous les delinquants sexuels mis en liberte dans la region du Pacifique. Ce changement du politique nous a donne une occasion unique de comparer une cohorte non selectionnee de delinquants sexuels traites (n = 403) avec une cohorte non traitee (n = 321) liberee au cours des annees anterieures. Apres une moyenne de suivi sur une periode de 12 ans, aucune difference n'a ete observee dans les taux de recidive sexuelle (21,1 % par opposition a 21,8 %), de recidive avec violence (42,9 % par opposition a 44,5 %) ou de recidivisme general (de n'importe quelle nature) (56,6 % par opposition a 60,4 %) pour les groupes traites et non traites respectivement. Le resultat est demeure comparable apres avoir controle la longueur de suivi, l'annee de liberation, l'age et sept facteurs de risque statiques codes a partir des dossiers criminels officiels. Une evaluation retrospective de la qualite du traitement n'a egalement montre aucun rapport avec les taux de recidivisme observes. Les facteurs de risque statique codes dans l'etude actuelle justifiaient l'ecart considerable dans le taux de recidivisme et pourraient facilement etre utilises pour ameliorer les controles statistiques dans les evaluations futures.

Providing treatment for sexual offenders is controversial. Narrative reviews all stress the weakness of existing studies (Furby, Weinrott, & Blackshaw, 1989; General Accounting Office, 1996; MacKenzie & Hickman, 1998), precluding strong conclusions regarding program effectiveness. The central problem concerns potential differences between the treatment and comparison groups. The standard method for minimizing differences is to randomly assign offenders to treatment and no-treatment groups; such designs, however, are difficult to implement and sustain in criminal justice settings. On average, the observed sexual recidivism rate for untreated sex offenders is approximately 15% after 5 years and 20% after 10 years (Hanson & Bussiere, 1998; Hanson & Thornton, 2000). When long follow-up periods are required, there is ample opportunity for the research design to be corrupted (e.g., "untreated" offenders receive treatment, administrative support collapses). Consequently, most sex offender treatment outcome studies were not initially designed as such; instead, they have taken advantage of "natural experiments."

The following examples illustrate the challenges faced when comparison groups are not randomly assigned. …