A differentiated view on the effects of sex offender treatment
In his “personal view” Dr. Ho claims “no evidence from academic or policy research has shown” that the Sex Offender Treatment Programme (SOTP) “significantly reduces sexual reoffending.” Ho notes that SOTP is “the standard psychological talking therapy used in prisons and secure psychiatric hospitals in England and Wales since 1991.” We therefore agree with him that evidence of its effectiveness deserves to be scrutinised closely. However, we think that Ho’s personal view is somewhat misleading. In support of his claims, the piece overlooked research that suggests findings contrary to his conclusions, and he infers uniformity of outcomes from heterogeneous studies.
Ho cites three pieces of evidence in support of his view, without mentioning details contained therein. The first is a Cochrane Collaboration review of psychological programmes applied to adult sex offenders. This review is based on a few, mainly North American randomized controlled trials (RCTs) that showed heterogeneous results. Even the authors of this review discussed whether RCTs are the only appropriate design in the difficult field of sex offender treatment. The second piece of evidence cited by Ho is not systematic research but an editorial he himself has co-authored. This critiqued a NOMS factsheet on SOTP, the claims of which were satisfactorily addressed (and, in our view, mitigated) by Mann et al. The third piece of evidence Ho quotes is an international meta-analysis (MA) of a wide variety of treatments applied to adult and juvenile sex offenders, co-authored by the second author of this response. This reference triggered our present letter.
As Ho cites the international MA of Lösel and Schmucker  in support of his view he obviously does not only comment on a specific British SOTP, but more broadly on psychosocial interventions for sex offenders. This is plausible insofar as there are several SOTPs for different target groups in Britain and only very few controlled evaluations (e.g., Friendship et al. with relatively positive results). However, contrary to Ho’s view the MA of Lösel and Schmucker  does not support his claim of ineffective sexual offender treatment. In fact a majority of the 80 primary evaluations in the MA showed positive effects on sexual recidivism, although these were only partially statistically significant due to small sample sizes. Hormonal treatment was most effective, but the respective evaluations were of low quality (a situation that still prevails [2,7]). Among psychosocial interventions cognitive/behavioural interventions had a clear significant effect. This finding is in agreement with other MAs on SOTPs (for an overview see Lösel & Schmucker ). Programmes that meet the Risk-Need-Responsivity model seem to be particularly effective. We agree with Ho that many evaluations of SOTP are not based on well-controlled designs. Therefore, Schmucker and Lösel  carried out an updated MA, which relied only on evaluations with equivalent treatment group (TG) and control group (CG) and reported a statistically significant mean reduction in sexual reoffending (TG = 10.1%, CG = 13.7%). Due to the generally low base rate of (official) sexual reoffending, this looks like a minor difference, but it indicates a reduction of approximately 26% in TGs compared to CGs. This effect size accords with the wider landscape of meta-analyses on sex offender treatment.[8,10]
The MA of Schmucker and Lösel  also found various moderator effects: Cognitive-behavioural and multi-systemic treatment as well as studies with small samples, medium to high risk offenders, more individualised treatment, and good descriptive validity revealed better effects. In contrast to treatment in the community and forensic hospitals, treatment in prisons did not show a significant mean effect, but some prison studies had rather positive outcomes. In relation to the prison vs. community topic Koehler and Lösel  carried out a systematic review of six MAs to investigate how the reoffending outcomes for sex offender treatments differ between settings. We found consistently greater mean effects among treatments delivered in the community (OR: 2.11; CI95%: 1.69 – 2.63) than for those delivered in custodial settings (OR: 1.49; CI95%: 1.15 – 1.82). Such disparities suggest that the conditions of confinement may attenuate the therapeutic effects of SOTPs, and also that community treatment (where it is possible for legal reasons) may make it easier to transfer learned thoughts and skills to the real world. Consequently, the view of Ho on SOTP should not be taken as emblematic of sex offender treatment as a whole. Inter alia, some diminution of effectiveness may be expected when treatments are delivered in custodial settings; however, this is not to say that there is a general absence of evidence for sex offender treatment.
There are valid criticisms to be made about sex offender treatment in general, and perhaps about British SOTP in particular. However, Ho’s portrayal mis-characterises the evidence at his disposal, overlooks other findings, and does not differentiate between features that are associated with treatment outcomes. In so doing, he risks discarding the promise of effective treatment suggested by the very “evidence of efficacy, provided through robust research” for which he calls. Instead of sweeping controversies about sex offender treatment we need hard empirical work on what works with whom, in what contexts, under what conditions, with regard to what outcomes, and also why. We assume Dr. Ho agrees on that.
 Dennis JA, Khan O, Ferriter M, Huband N, Powney MJ, Duggan C. Psychological interventions for adults who have sexually offended or are at risk of offending. Cochrane Database Syst Rev 2012;12:CD007507.
 Duggan C, Dennis J. The place of evidence in the treatment of sex offenders. Crim Behav Ment Health 2014;24:153-162.
 Ho DK, Ross CC. Cognitive behaviour therapy for sex offenders: too good to be true? Crim Behav Ment Health 2012;22:1-6.
 Mann RE, Carter AJ, Wakeling HC. In defense of NOMS’ view about sex offending treatment effectiveness: A reply to Ho and Ross. Crim Behav Ment Health 2012;22:7-10.
 Lösel F, Schmucker M. The effectiveness of treatment for sexual offenders: a comprehensive meta-analysis. J Exp Criminol 2005;1:117-46.
 Friendship C, Mann RE, Beech AR. Evaluation of a national prison-based treatment program for sexual offenders in England and Wales. J Interpers Viol 2014;18:744-759.
 Schmucker M, Lösel F. The effects of sexual offender treatment on recidivism: An international analysis of sound quality evaluations. Under review.
 Lösel F, Schmucker M. Treatment of sex offenders. In: Weisburd D, Bruinsma G, editors. Encyclopedia of criminology and criminal justice. New York: Springer; 2014. p. 5323-5332
 Hanson K, Burgon G, Helmus L, Hodgson S. The principles of effective correctional treatment also apply to sexual offenders: A meta-analysis. Crim Justice & Behav 2009:36: 865-891.
 Lipsey MW, Cullen FT. The effectiveness of correctional rehabilitation: A review of systematic reviews. Annual Rev Law & Soc Sci 2007;3:297-320.
 Koehler J, Lösel F. 2014. Can prisons reduce reoffending? A meta-evaluation of custodial and community offender rehabilitation programs. Paper presented at the Stockholm Criminology Symposium 2014; Stockholm, Sweden.
 Maguire M, Grubin D, Lösel F, Raynor P. ‘What works’ and the Correctional Services Accreditation Panel: Taking stock from an inside perspective. Criminol & Crim Justice 2010;10:37-58.
Competing interests: Friedrich Lösel is a member of the Correctional Services Accreditation and Advice Panel (CSAAP) of England and Wales and a past chair of the prior accreditation panel CSAP. These are independent roles that do not imply any conflict of interest. In contrast, they enable a differentiated view on the practice of offender treatment in Britain.