A Quasi-Experimental Evaluation of High-Intensity Inpatient Sex Offender Treatment in the Netherlands

Participants

The study sample consisted of two subsamples of men convicted for a contact sexual offense in the Netherlands. The first subsample included all offenders who were discharged from high-intensity inpatient treatment between 1996 and 2002 (n = 106). The second subsample consisted of a random selection of 25% of adult male sex offenders who were discharged from prison between 1996 and 2002, without being referred to any form of treatment (n = 188). This subsample was obtained by selecting half of all Dutch jurisdictions, stratified for urban and rural areas, and subsequently randomly selecting half of the obtainable files from each selected jurisdiction. Both samples added up to a total of 294 sex offenders. These subsamples correspond to the inpatient and no treatment subsamples as described in Smid, Kamphuis, Wever and Van Beek (2014) and overlap with the inpatient and no treatment subsamples described in Smid, Kamphuis, Wever, and Van Beek (2013).

A total of 28 records were discarded for a diversity of reasons: Six offenders deceased before discharge, two (illegal immigrant) offenders were extradited directly after discharge, and six offenders were not actually discharged but left the treatment facility to return to prison as result of a new conviction. For 14 offenders (five inpatients and nine prisoners), we were unable to find a new extract of criminal records to assess new offenses; 12 of those deceased before 2006, and their record was deleted from the judicial system, as was customary up to that date. Follow-up data for the two remaining offenders was missing for unknown reasons. This resulted in a final sample of 266 offenders who were included in the subsequent analyses, 34% discharged inpatients (n = 90) and 66% discharged from prison (n = 176). The mean age at discharge for the total sample was 37.48 (SD = 11.74), with a minimum age of 18 and a maximum age of 78. Of all offenders, 70.3% (n = 187) had a prior criminal charge/conviction (n = 167) and 28.9% (n = 77) had a previous charge/conviction for a sexual offense. The mean Static-99R score of the total sample was 3.20 (SD = 2.46). The distribution of offenders over Static-99R risk levels differed significantly between the two subgroups, χ²(3, N = 266) = 39.74, p < .001, with inpatient offenders more often showing moderate-high and high-risk levels and untreated offenders more often showing low-moderate and low-risk levels (see Table 1). On average, higher risk offenders were selected for inpatient treatment, but offenders of all risk levels were present in both groups. No cells showed an expected count of less than 5 and only one cell (low-risk inpatient treatment) showed an observed count (9) below the minimum expected count (15.2).

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Table 1.

Static-99R Risk Levels Compared Between Untreated and Inpatient Sex Offenders.

Static-99R risk level	Untreated offenders (n = 176)	Inpatient offenders (n = 90)
Low	32.4% (57)	10.0% (9)
Low-moderate	34.1% (60)	17.8% (16)
Moderate-high	23.9% (42)	41.1% (37)
High	9.7% (17)	31.1% (28)

Note. χ²(3, N = 266) = 39.74. p < .001.

Setting

Pretrial psychological assessment for sex offenders is not a standard procedure in the Netherlands. Instead, judges can order discretionary psychological assessment by an independent psychologist or psychiatrist (or both). In approximately 5% of all sex offender convictions, a consulted examiner advises the court to refer a sex offender to mandatory inpatient treatment (Brouwers & Smit, 2005). This form of treatment is referred to as “ter beschikking stelling” (TBS) which translates as “put at the disposition of the government” meaning the treatment is imposed by the state for as long as the state sees fit. This treatment was primarily designed to protect society against reoffending and is imposed on offenders who are considered to be at serious risk to reoffend. It is of indefinite length, but each individual case is reevaluated in court every two years. Though treatment was intended to end when treatment providers determine that the offender has made sufficient progress, judges regularly decide to end treatment against the advice of the treatment providers: the so-called “contrarian rulings.”

The referral of sex offenders to this and other forms of treatment has for the longest time been guided by unstructured clinical procedures. Prior research has shown that this practice resulted in a situation in which sex offenders, irrespective of their actuarial risk levels, were referred to inpatient treatment, or to prison without any form of treatment (Smid et al., 2013). This indiscriminate treatment allocation provided the opportunity to compare the recidivism rates of released inpatients with untreated offenders of comparable actuarial risk levels (consistent with the CODC guideline to take risk levels into account). Offenders who were discharged based on contrarian rulings can be regarded as dropouts, and prior research has shown these offenders to be at considerably higher risk to reoffend than those who completed treatment (De Vogel, De Ruiter, Hildebrand, Bos, & Van de Ven, 2004). These dropouts were included in the treatment group to provide intention-to-treat analysis, consistent with the CODC guideline to take into account dropouts. The prematurely discharged offenders constituted 45% of all discharged offenders, and their treatment duration (M = 91.87 months, SD = 38.53) did not differ significantly from the regularly discharged offenders (M = 104.83 months, SD = 42.12, t = 1.42, p = .16).

The six offenders who recidivated during treatment and were reincarcerated during the time frame of the current study were excluded from this study sample because they had not been discharged yet, and thus fell out of our sample frame. Of note, the data in this study included all offenders who were discharged between 1996 and 2002, as opposed to offenders who were convicted during that time frame. Although their recidivism could clearly be regarded as a form of treatment failure, their inclusion would also have required the inclusion of all offenders still in treatment who did not recidivate during treatment, which was beyond the scope and frame of this study. Generally, offenders who recidivated during inpatient treatment would return to treatment after their reconviction and any served prison time. Accordingly, our sample did include seven offenders who recidivated during treatment, returned to treatment, and were eventually discharged between 1996 and 2002. The mean Static-99R scores of the six excluded non-discharged inpatient offenders was very similar to the Static-99R scores of the seven included discharged inpatient offenders who had recidivated during an earlier stage of treatment, M = 6.17 (SD = 0.98) versus M = 6.14 (SD = 2.12), p = .98.

Procedure

Participants’ criminal files, as compiled by the legal system for their index conviction (index files), were studied to retrospectively code the items of the Static-99R. The index files generally contained offenders’ criminal record at the time of conviction, ² minutes concerning the index offense (with statements of both offenders and victims), and the exact indictment, verdict, and sentence, including any imposed treatment measures. The majority (69.9%) of the files contained a report concerning some sort of pretrial assessment (100% of the inpatient files and 55.1% of the prisoner files). All assessments were unstructured, and none of the offenders was assessed for risk level with an actuarial instrument at the time of conviction. A total of 10 trained coders scored the items based on the file information in the 266 files. The age-related Static-99R item was scored according to the offenders’ age at the time of discharge.

After the coding of the Static-99R, the offenders’ current criminal records were requested to acquire data on their reoffending. The current criminal records were coded by two independent raters who were blind to the initial risk assessment results. The outcome measure “sexual recidivism” was defined as any charge or conviction for a new offense that was sexual in name (e.g., rape, abuse, child pornography possession). “Violent recidivism” was defined as any charge or conviction for a new offense that involved any actual, attempted, or threatened physical harm to the victim and included all sexual offenses. Violent offenses included explicit display of violence, such as assault, murder, or robbery, and also included more covert forms of violence, such as threats, extortion, and stalking. Follow-up time was counted from the day of discharge to the day that the follow-up criminal record was retrieved, or, in case of deceased subjects, from the date of discharge to the date of death.

To test whether the quasi-experimental design resulted in comparable groups, demographic and clinical characteristics were compared between the treated and untreated offenders at each of the four risk levels, consistent with the CODC guideline to take into account potential confounding variables. Some demographic and legal variables were assessable for all subjects, that is, offender age, number of children, education level, relationship history, employment, ethnicity, prison sentence, and age of victim(s). Other, more psychological variables were only available for offenders with pretrial assessment reports, that is, for all of the treated offenders and for 55% (n = 97) of the untreated offenders. In these cases, more extensive information was documented and the reporting social worker, psychologist, or psychiatrist generally assessed more psychological information. The included variables were coded according to recorded statements of the offender or assessment by the reporter. These variables included general cognitive ability (e.g., mention of mental retardation); sexual orientation toward adults; mention of any major mental disorder, current or in the past; mention of any personality disorder (PD) or traits of PD; mention of substance abuse; mention of prior psychological/psychiatric treatment; and mention of childhood abuse.

Treatment

The Dutch mandatory inpatient sex offender treatment was provided after completion of any prison sentence by several Dutch health care facilities. These facilities, although closed, were not prison-like, and treatment was delivered in a generally supportive non-punishing atmosphere. Specific treatment programs varied among the 13 different facilities providing this treatment, but always included psychotherapy (individual, in groups, or both), most often a relapse prevention program, and adjunctive job/study orientation and pharmacotherapy when indicated. No treatment differentiation was made according to risk levels, but treatment was extensively tailored to the offenders’ individual responsivity. Treatment targets included the established criminogenic need factors (e.g., antisocial attitudes, offense supportive attitudes, substance abuse), as well as other factors not directly linked to recidivism risk (e.g., major mental disorder, empathy, social skills). The average treatment duration for the offenders included in the study sample was 8 years and 4 months (SD = 42.6 months). This duration refers to the total time they spent in and under supervision of the TBS clinic; this period involved participation in coordinated sex offender programming as well as participation in more general treatment-relevant programs. During the course of the treatment, the offenders progressively gained more extended forms of leave. For most offenders, their resocialization included a so-called “transmural” phase (halfway houses), when they were living outside the facility while still under supervision. Some offenders were transferred between facilities during treatment. For a more detailed description of TBS treatment, see Feldbrugge (2007). For an example of a treatment program of a specific treatment facility, see Van Binsbergen, Keune, Gerrits, and Wiertsma (2007).

Instruments

The Static-99 (Hanson & Thornton, 2000) is the most widely used and most extensively researched actuarial risk assessment instrument for sex offenders (Hanson & Morton-Bourgon, 2009). It consists of 10 items yielding a score between “0” and “12,” referring to four risk levels. The most recent meta-analysis (Hanson & Morton-Bourgon, 2009) summarized 63 findings from published and unpublished studies that included more than 20,000 subjects: A median Cohen’s d = .74 (mean d = .67) for sexual recidivism and a median Cohen’s d = .51 (mean d = .57) for any violent (including sexual) recidivism were observed. Recent research found age to add incrementally to the predictive validity of the Static-99, resulting in a revised scoring system (Helmus, Thornton, Hanson, & Babchishin, 2012). The Static-99R age item distinguishes four age categories yielding a score between “–3” and “+1.” Total scores of the Static-99R range between −3 and +13, referring to four risk levels: low (−3 to +1), low-moderate (2 or 3), moderate-high (4 or 5), or high (6 or higher). The Static-99R significantly predicted sexual and violent (including sexual) recidivism for a national Dutch sex offender sample (Smid et al., 2014), which the current sample is a subgroup of; Static-99R area under the curve (AUC) values varied between .71 and .74 for the various follow-up periods and outcome measures. In the current sample, the Static-99R predicted both sexual (AUC = .78) and violent (including sexual) recidivism (AUC = .73) significantly over a 10-year fixed follow-up period. For the subgroup of untreated offenders, the respective AUC values for sexual and violent (including sexual) recidivism were .83 and .78. For the subgroup of inpatient offenders, the AUC values for sexual and violent (including sexual) recidivism were .66 and .71. An earlier study also found lower predictive accuracy of static risk factors regarding treated offenders (Langton et al., 2007), indicating that treatment may render some static risk factors less valid.

Statistical Analysis

First, to assess baseline differences between the treatment and no-treatment group, comparisons of characteristics were conducted at each Static-99R risk level separately, by means of t test for the age-related variables, Mann−Whitney U tests for the ordinal variables, and chi-square analyses for categorical variables. No Bonferroni corrections were applied, as we aimed to conduct a stringent test of equivalence. Second, to assess their relationship to recidivism, variables showing significant a priori differences between the treated and untreated offenders were entered in a Cox regression survival analysis, with both risk level and treatment as covariates.

Third, Cox regression survival analyses were used to compare sexual and violent (including sexual) recidivism rates of treated and untreated offenders, while controlling for Static-99R score and individual differences in follow-up time (consistent with the CODC guideline to take into account follow-up time). Survival time was defined as the time between the date of discharge from treatment or prison to the date of perpetration of the first sexual or violent (including sexual) reoffense. If no new sexual or violent reoffense occurred, survival time was calculated as the time between discharge date and the retrieval date of the new criminal record, or date of death when indicated. To control for risk level, the Static-99R total score was included as a covariate. Seven offenders recidivated with a violent offense before they recidivated with a sexual offense, and their survival time for sexual recidivism was adjusted for the estimated time spent in prison for the earlier violent offense.

Finally, to assess differences in recidivism rates between treated and untreated offenders at each risk level, Cox regression survival analyses were conducted for each outcome measure including treated and untreated offenders stratified by the four Static-99R risk levels (low, low-moderate, moderate-high, and high).