Assessment of treatment outcome for paraphilias involving sexual aggression is fraught with methodological complexity. Indeed, some forensic clinicians doubt whether sex offenders have “psychiatric” disorders at all, inasmuch as their behavior is criminal and appears ego-syntonic (Maier 1999). Most treatment and outcome studies understandably concentrate on the most common serious sexual-aggressive behaviors: rape of children or adults. Although studies may report recidivism rates for other paraphilic sex-offending behaviors, such as exhibitionism and voyeurism, such reports often do not include standardized treatments or comparison groups. In addition, as currently classified, rape of an adult is not a “paraphilic” disorder, in part because there is controversy as to whether adult rapists consistently demonstrate deviant sexual arousal as ascertained by the penile plethysmograph (also called phallometry), the current laboratory standard for assessing deviant sexual arousal (Seto and Barbaree 1997; Ward et al. 1997). Furthermore, the designation of “child molester” is much broader than the diagnosis of pedophilia, and not all child molesters are paraphilic. For example, a man or woman who has sexually violated a child or children while intoxicated or while otherwise behaviorally disinhibited could be prosecuted and incarcerated for child molestation but not have a clinical history of repetitive, intensely sexually arousing erotic fantasies regarding children (i.e., pedophilia). Finally, although at present cognitive-behavioral relapse prevention treatment is the most frequently prescribed comprehensive treatment for paraphilic sex offenders in the United States and Canada (Freeman-Longo et al. 1994), different programs use differing combinations of additional treatments, such as behavioral therapies, social skills training, anger management, group therapy, victim empathy, and psychoeducation groups (Freeman-Longo et al. 1994). In addition, in recent years more aggressive outpatient management has included controversial state-regulated sex offender registries and community notification programs (Berliner 1996; Freeman-Longo 1996) and community-based intensive probation involving the use of monitoring bracelets and polygraph testing. Obviously, these kinds of intensive and expensive interventions are not indicated for the treatment of nonviolent PAs and PRDs.

Sex offender self-reports are not considered to be the primary or most reliable indicators of current offense patterns or recidivism rates (Grossman and Cavanaugh 1990; Haywood et al. 1993). In addition, it has been estimated that fewer than 7% of all sex crimes are ever brought to police attention and that fewer than 1% of all sex offenders are arrested (Abel et al. 1984)! These pessimistic data may have changed in recent years, however, especially as sexual crimes have been aggressively publicized and sex offender registries have been established in many states.

The operational definition for recidivism or relapse varies between studies of sex offenders. For example, using the rearrest rate for sexual crimes as the primary outcome variable may be too narrow a definition for sex offender recidivism rates. Many of the more recent studies ascertain recidivism rates by including episodes of sexual violence as well as arrests for other criminal behaviors (Hanson and Bussiere 1998). Finally, ascertainment of recidivism depends on the time frame employed. For example, although it is difficult to follow a consistently treated group of sex offenders for 10 years or longer, longer follow-up periods yield higher recidivism rates (Hanson et al. 1991). Despite these caveats, a recent meta-analytic study of recidivism (N = 1,313) in sex offenders did demonstrate modest but significant treatment effects for both comprehensive cognitive-behavioral treatments and antiandrogen treatment (Hall 1995).

In the most comprehensive meta-analysis to date, Hanson and Bussiere (1998) examined data from 61 follow-up studies of sex offenders (N = 23,393) to establish predictors of relapse among these individuals. The average recidivism rate for sex offenders was 13.4% (18.9% for rapists [n = 1,839] and 12.7% for child molesters [n = 9,603]) over a mean follow-up period of 4-5 years. In addition, among the relapsing offenders, rapists were more likely than were child molesters to commit nonsexual violent crimes. The demographic variables associated with recidivism were younger age and single marital status. The strongest predictors of recurrent sex offenses were measures of sexual deviancy, as determined by penile plethysmography, especially sexual arousal to children. Sex offense recidivism rates were higher in men with prior sex offenses, a younger age at first offense, multiple victims, extrafamilial victims, multiple and diverse sex crimes, and victimization of strangers or males. Failure to complete treatment was a moderate predictor of recidivism as well. Indeed, in other reviews of psychological treatments for sex offenders, those who completed treatment relapsed at a significantly lower rate than did those who received no treatment or who dropped out of treatment (Alexander 1999; Grossman et al. 1999; Marques 1999). Finally, a developmental history of sexual abuse, current psychological problems, or alcohol abuse was not specifically associated with increased sex offense recidivism.

In contrast to the large number of treatment studies of sex offenders, including paraphilic individuals, no studies exist on treatment outcome of specific nonviolent paraphilias such as sexual masochism, fetishism, or transvestic fetishism. Outcome studies for PRDs are also very limited. Retrospective reports indicate that the combination of individual psychotherapy and 12-Step sexual addiction group therapy significantly reduced relapse rates in men and women with PRDs (Carnes 1991; Naditch and Barton 1990). These studies, however, were based on retrospective surveys, did not include consecutive cases, and did not control for adjunctive antidepressant treatment.