| ||Literature Coverage Dates||Number of Studies||Number of Study Participants|
|Meta-Analysis 1||1990 - 2009||5||0|
|Meta-Analysis 2||1990 - 2001||9||2986|
|Meta-Analysis 3||1990 - 2009||4||284|
|Meta-Analysis 4||1990 - 2014||8||802|
Schmucker and Lösel (2017) conducted a meta-analysis of therapeutic treatment programs for males who had been convicted for a sexual offense or committed acts of illegal sexual behavior that would have led to a conviction if officially prosecuted. This meta-analysis updated a previous meta-analysis conducted by the researchers in 2005. The researchers searched a broad range of literature databases, scanned previous reviews and primary studies on the topic, hand-searched 16 relevant journals, carried out an internet search of pertinent institutions, and personally contacted experts in the field of sex offender treatment. Studies were included if they met the following criteria: 1) used a randomized controlled trial design or quasi-experimental design, which employed matching procedures to statistically control for potential biases; 2) examined intervention programs that included therapeutic measures (i.e., psychosocial or organic treatment approaches); 3) reported official recidivism data as an outcome and provided sufficient information for effect size calculation; and 4) had a sample size of at least 10. There were no restrictions with regard to country of origin or language, and both unpublished and published studies were eligible.
This method resulted in a final sample of 27 studies. Occasionally, a reference contained more than one eligible study, so the authors used the individual study as the unit of analysis. Further, some studies presented results of subgroups. The authors used the subsamples as units of analysis when this would improve equivalence between treated and control groups and the report allowed for a differentiated coding of the individual subsamples. This resulted in 29 eligible comparisons.
This study pool comprised 4,939 treated and 5,448 untreated offenders. Only about one fifth of the comparisons were derived from randomized controlled trials. A quarter of the comparisons (7 comparisons) were retrieved from unpublished sources. Most comparisons appeared in studies published since 2000 (14 comparisons), 11 during the 1990s, and 4 during the 1980s. Eleven of the comparisons were published in studies that took place in Canada, eight in the United States, three in Great Britain, three in Germany, and four in unknown locations. Eighteen were published as journal articles, four as books or chapters in a book, and seven were unpublished. In 21 of the comparison, the mode of treatment was primarily cognitive-behavioral; however, four used a therapeutic community approach, two used an insight-oriented psychotherapeutic approach, and two used multisystemic therapy. No studies on hormonal treatment or organic treatment approaches met the inclusion criteria. Twenty-six of the comparisons examined treatments specific to sex offenders, and three were general. Twelve of the comparisons evaluated treatments delivered in outpatient settings, 10 in prisons, 5 in hospitals, and 2 in mixed settings.
The mean age of the treated offenders across all comparisons was 31.13 years. However, a subsample of five comparisons that focused exclusively on juvenile sex offenders was used for the CrimeSolutions.gov review (17.2 percent of the total meta-analysis sample). The specific characteristics about the juvenile-only studies were not provided.
The meta-analysis used odds ratio (OR) to measure effect sizes. Effect sizes were calculated using a random effects model. For studies that did not report statistics that could be easily transformed into OR, the authors used standard procedures to calculate Cohen’s d and then used these statistics to calculate OR. Whenever possible, participants who dropped out of the treatment program were included in the treatment group (i.e., intent to treat).Meta-Analysis 2
Reitzel and Carbonell (2006) conducted a meta-analysis of juvenile sex offender treatment effectiveness. The comprehensive search strategy included published and unpublished studies from 1975 through 2003. To be included in the meta-analysis the studies were required to have a sample of juveniles (ages 7 through 20) who were adjudicated for a sex offense, with a portion of the sample participating in sex offender treatment and either a no-treatment control or a comparison treatment group.
A total of nine studies (four published, five unpublished) from 1990 through 2003 were included in the final analysis. The total offender sample size was 2,986 (male, n=2,604; female, n=121) of which 1,331 were in no-treatment control groups, 1,301 were in sex offender treatment groups, and 354 were in comparison treatment groups. Study group assignments were either unknown or unclear (one study), assigned based on need or risk (three studies), assigned incidentally (three studies), or assigned randomly (two studies). The mean age was 14.6 and included 41 percent minority youth.
Effect sizes were calculated using a fixed-effects model due to the small number of included studies. The maximum likelihood estimate (MLE) of odds ratio was calculated for each study. The MLE of odds ratio was then converted into a natural log odds ratio for statistical analysis. Additionally, studies were weighted based on their sample size.Meta-Analysis 3
Hanson and colleagues (2009) conducted a meta-analysis to examine whether principles associated with effective interventions for general offenders (risk–need–responsivity) would also apply to psychological treatments for sexual offenders. A comprehensive search of databases was conducted. To be included in the meta-analysis, studies had to examine treatment effectiveness by comparing recidivism rates using a sex offender population with a matching comparison group of sex offenders. The authors defined sex offenders as “offenders with sexually motivated offenses against an identifiable victim” (p. 868). Participants in the control/comparison group could have received an alternate treatment, less treatment, or no treatment. In order for the studies to meet the “need” principle of the RNR model, at least 51 percent of the treatment had to target criminogenic needs, such as antisocial lifestyle, impulsivity, or negative peer associations. Services in the treatment program met the “responsivity” aspect of RNR when the treatment was provided in such a way as to match the needs and learning style of the client.
The number of eligible studies was narrowed down using the Collaborative Outcome Data Committee (CODC) guidelines, which help to determine the extent to which a study’s features indicate possible bias when estimating treatment effect. Only studies categorized as weak, good, and strong were included. This resulted in a total of 23 studies included in the analysis. A majority of offenders included in the studies were adult males (three studies indicated the inclusion of some female offenders in the sample). Fourteen studies were published and nine were unpublished. The majority of the studies (74 percent) were from North America (Canada and the United States). The sample sizes ranged from 16 to 2,557. In 10 of the studies, the treatment programs were offered in institutions, and in 11 studies they were offered in the community (in two studies the treatment was offered in both settings).
Of these 23 studies, only four were specifically focused on juvenile sex offenders. The four studies were published between 1990 and 2009. Three of the four studies were published in peer-reviewed journals, and one was a master’s thesis. There were a total of 284 juveniles (including treatment and control group members) across all four studies. Other characteristics about the juvenile-only studies, such as gender or race/ethnicity breakdowns, were not provided.
Statistics were calculated using both a fixed effect and random effect models and by calculating odds ratio (OR).Meta-Analysis 4
Kettrey and Lipsey (2018) conducted a meta-analysis to assess the effectiveness of psychosocial, therapeutically oriented treatments on sexual offending of juvenile sex offenders (JSOs). To identify studies, the researchers searched 62 electronic databases, including a large parent meta-analysis database of studies evaluating the effects of psychosocial, therapeutically oriented interventions or therapies among juveniles who have committed a chargeable offense. To identify unpublished literature, the researchers searched Google Scholar, the webpages and reference pages of authors of eligible or nearly eligible studies, and the reference lists of the previous meta-analyses that evaluated JSO interventions.
To be eligible for inclusion, studies had to examine treatments provided exclusively to JSOs under the age of 21 who committed acts that constituted chargeable sexual offenses. Participants had to reside in the United States or a predominantly English-speaking country. Eligible treatment programs had to be implemented individually with JSOs or in groups composed entirely of JSOs; however, they could not be implemented in mixed groups that included juveniles who had not committed sexual offenses. Studies had to have used random assignment of juveniles to conditions, matched them on one or more recognized risk factors for recidivism (e.g., offense history, rape myth acceptance), or reported baseline measures of group differences on such risk factors. Finally, studies were only eligible if they reported quantitative outcome data for at least one delinquency measure, were published or reported in 1950 or later, and conducted no earlier than 1945. Studies that examined the effects of pharmaceutical or medical treatments, or interventions that did not have a primary therapeutic orientation (e.g., incarceration, probation, deterrent programs) were excluded.
The search resulted in eight studies described in 12 reports that met the eligibility criteria, of which seven were published journal articles, and one was an unpublished thesis. Four studies were conducted in the United States, two in Australia, and two in Canada. One study was a randomized controlled trial, whereas the remaining studies either matched treatment and comparison groups on some set of background characteristics or reported baseline measures of at least one risk factor for recidivism that could be used to assess group equivalence. The study pool comprised 415 treated and 322 untreated subjects. Sample sizes ranged from 16 to 190. Treatment samples were predominately male (90 to 100 percent), and among the four studies that reported race or ethnicity, largely white (53 to 67 percent). The mean age (reported in four studies) ranged from 13.5 to 15.4 years, and three studies included some juveniles younger than age 13. In terms of the main form of treatment, three studies examined group counseling, two examined family counseling, one examined individual counseling, and one examined mixed counseling (a combination of group, family, and individual). The remaining study examined a skills-building program, specifically an adventure-based, behavior management program. All programs were specifically tailored to JSOs. Three of the treatments were provided in residential settings, and the other five were delivered in community settings.
Seven of the eight studies reported sexual recidivism outcomes, while six of the eight reported general recidivism outcomes. Statistics were calculated using both fixed effect and random effect models and by calculating odds ratios.