The present study aimed to identify variables, including substance-related and psychiatric problem variables, which predict return to the criminal justice system in prisoners with substance use problems. Several substance-related risk factors were seen, even when controlling for type of crime and the duration of the index sentence. Return to the criminal justice system was predicted by the use of heroin and amphetamine, rather than with other substances, and a more pronounced increase in risk was seen for clients with a history of injecting drug use. Also, recidivism was associated with a higher number of used substances, as well as with a history of psychiatric in-patient treatment, difficulty controlling violent behaviour, male gender, and homelessness.
The association of criminal recidivism with male gender is consistent with previous data [8
], and poor living conditions previously also have been demonstrated to increase the risk of relapse into crime [8
]. Also, psychiatric morbidity, including psychiatric in-patient treatment, previously has been shown to increase the risk of criminal relapse [9
], although this finding has not been consistent in the literature [8
]. Associations with psychiatric in-patient treatment and difficulties controlling violent behaviour were relatively weak in the present study.
The main purpose of the present paper was to study the risk of criminal recidivism related to substance use problems. It is very likely that the types of crimes committed vary depending on the primary drug used by a client, but in the present study, even when controlling for the main types of crimes for which clients were sentenced, associations with some particular features of substance use remained as significant predictors of returning to the criminal justice system. The present study demonstrated independent increases in risk for both of the most commonly injected drugs in the present setting, amphetamine and heroin. In addition, the role of injection drug use was demonstrated, and appears to add some further increase in risk of recidivism, over and above the risk conferred by heroin or amphetamine use alone. The association between injection drug use and criminal recidivism may be mediated by other factors related to both constructs, possibly indicating that a higher degree of deviant behaviour may involve injection drug use and may also be associated with a worse outcome with respect to criminality. However, there also have been data indicating that criminality was actually rather predicted by non-injection use of heroin [28
], indicating that the link between injection drug use and criminal behaviour may need further focus in research.
The link between amphetamine use and criminal recidivism has been sparsely addressed in previous literature. There are some data indicating an association in methamphetamine users, although in a different setting and a younger group of methamphetamine users compared to the amphetamine users in the present study [29
]. Sweden has seen a long history of a dominating abuse of amphetamine, in contrast to many other countries [30
], including high rates of amphetamine use in the criminal justice population, making this the leading substance in the dataset studied here [21
]. More remains to be understood about the mechanisms mediating the connection between amphetamine and crime, but the elevated risk of relapsing into crime may have important implications for follow-up and treatment of primary amphetamine users. The development of effective treatment for stimulant addiction historically has been difficult. The last few years have seen emerging scientific support for naltrexone treatment in amphetamine addiction [31
], although to date, no medication is formally approved for this type of addiction.
In addition to amphetamine, an elevated risk of relapse was seen also for clients with a history of heroin use, and for clients reporting a higher number of substances used prior to incarceration. The association between heroin use and criminal behaviour is well-known, and the link with recidivism may not be surprising given the high cost of using heroin regularly [3
]. Also, treatment of heroin addiction has been shown to decrease the risk of criminal relapse [32
A significant association was also seen between polysubstance use at baseline and criminal recidivism, with an increase in the risk of recidivism for a higher number of substances used prior to incarceration. While polysubstance use previously has demonstrated a connection to severity of substance use in several other aspects, including mortality, suicide [33
] and, in the present dataset, higher rates of psychiatric problems [22
], the association between polysubstance use and criminal recidivism appears to be a novel finding. Factors mediating this connection are unclear, but may possibly be related to a generally higher severity of substance use complications in subjects who use several substances. Reasons for using multiple substances may differ, and may include both the desire of combining drug effects, and the use of one substance in order to control consequences of the use of another drug [35
However, the characteristics of individuals with a high degree of polysubstance use are insufficiently understood, and further research may be required in this field. The principal purpose of the present study was to assess the role of substance use variables in the prediction of criminal recidivism when controlling for other factors such as type of crime at baseline. Therefore, type of crime at the index sentence was used mainly as a co-variate to control for in the analysis of potential predictors related to substance use. Likewise, the duration of the index sentence was included in the model as a theoretical proxy variable of severity of the index crime, and displayed an association between recidivism and a shorter time spent in incarceration. The positive association between criminal recidivism and baseline property crime, and the negative associations with baseline violent crime or drug crime, merit further research in order to better understand mechanisms mediating these findings. Relapse rates in clients with different types of criminality may be related to several conditions. For instance, the type of follow-up and treatment referrals offered to clients at prison release may differ according to the type of crime committed before the sentence. There is a paucity of research assessing risk factors of violent recidivism in prisoners, and some of the knowledge in this area comes from research in forensic psychiatric patients. In that setting, a violent index crime has tended to be associated with a lower risk of criminal recidivism [12
], but rates of violent re-offending have been shown to be higher in prisoners than in forensic psychiatric patients [13
]. In comparison to other Swedish data on relapse rates in violent offending [13
], any criminal recidivism was more common in our study, where a majority of clients with a violent index crime returned to the criminal justice system. However, we have little previous data on the risk of relapse in specific types of crime in prisoners with substance use, and there is reason to believe that re-offending may be more common in substance users than in other criminals [13
]. In the present study, property crime was associated with a higher risk of returning to the criminal justice system. In previous descriptive data from the Swedish criminal justice system [36
], although with no further analysis of risk factors, exceptionally high rates of recidivism were reported in sub-groups of clients. That report pointed out property crime as an index offense very often associated with future relapse; relapse rates in male prisoners with previous convictions even reached above 80 percent. However, subgroups of subjects sentenced for drug crimes also had very high rates of recidivism [36
], whereas in the present study, an index drug crime was relatively protective of recidivism compared to the rest of the database. More research may be required in order to improve the understanding of the associations between baseline criminality and relapse. In the previous statistics reported from the whole criminal justice population, regardless of the type of index conviction, rates of recidivism were reported to be 40 percent within three years, only a slightly longer period of time than the average follow-up time in our study. In the present study, rates of recidivism were higher, 69 percent. The present analysis included only prisoners and only substance users, which may have identified a subset of high-risk individuals with respect to relapse into criminal behaviour. Again, the factors mediating these associations may related to characteristics of a specific substance-using prison population, and clearly, there is need for more research about factors mediating the associations between index crime and prospective risk of recidivism.
Limitations and strengths
The present study has several limitations. First, baseline data are based on self-reported data, which are associated with a risk of recall bias, especially given the time elapsed between prison entry and the interview. Also, while baseline substance use and other characteristics are used as predictors of future criminal recidivism, we did not have access to data describing the situation preceding the relapse into criminal behaviour. Also, from the data available, we were unable to assess the number of future relapses, but rather followed clients from release from prison until the next entry into the criminal justice system or until data were censored. In addition, the present data are based on clients assessed by prison staff as part of a national struggle to improve client-specific and nationwide assessment and interventions with respect to the substance use situation in Swedish criminal justice clients, and therefore, the database studied here is not based on a randomized selection or on any other type of systematic selection, which is a limitation. For reasons related to the overall purpose of the implementation of ASI assessments in this setting, drug users were relatively more common compared to problematic alcohol users, compared to substance users in the whole prison system.
Also, clearly, this kind of registry study can not describe all criminal acts for which a client is never sentenced, and as some offenses may be more likely than others to lead to a new verdict, registry data from the criminal justice system can not fully reflect the true extent and features of criminal behaviour.
On the other hand, the present study is based on a relatively large dataset, and enables the analysis of a large number of potential predictors of criminal relapse. This includes the prospective follow-up design with predictors derived from baseline assessments with a well established interview instrument [15
], including relatively detailed data on substance use pattern prior to incarceration, making it possible to indicate problem areas that need assessment, intervention and follow-up in criminal justice clients with substance use problems.